Dr. Matt Walker: Using Sleep to Improve Learning, Creativity & Memory

00:00:00.000 | - Welcome to the Huberman Lab guest series,

00:00:02.440 | where I and an expert guest discuss science

00:00:05.120 | and science-based tools for everyday life.

00:00:07.280 | I'm Andrew Huberman,

00:00:09.720 | and I'm a professor of neurobiology and ophthalmology

00:00:12.720 | at Stanford School of Medicine.

00:00:14.680 | Today's episode marks the fourth

00:00:16.400 | in our six-episode series all about sleep

00:00:19.000 | with expert guest, Dr. Matthew Walker.

00:00:21.320 | During today's episode, we discuss sleep and learning,

00:00:24.180 | as well as the impact of sleep

00:00:25.680 | and the specific stages of sleep on creativity and memory.

00:00:29.400 | We talk about when and how long to sleep

00:00:31.520 | relative to different bouts of learning,

00:00:33.600 | as well as the role of naps in consolidating information

00:00:36.360 | that you are trying to learn.

00:00:37.600 | We discuss the science and protocols of sleep

00:00:39.980 | as it relates to both cognitive learning and motor learning,

00:00:43.640 | and the mechanism by which sleep encodes memories.

00:00:46.400 | As with the previous episodes in this series,

00:00:48.600 | today's episode includes information

00:00:50.200 | about the biology of sleep, as well as practical tools,

00:00:53.340 | that is protocols, in which you can use sleep

00:00:56.120 | to improve your learning, memory, and creativity.

00:00:59.240 | Before we begin, I'd like to emphasize that this podcast

00:01:01.880 | is separate from my teaching and research roles at Stanford.

00:01:04.560 | It is, however, part of my desire and effort

00:01:06.680 | to bring zero cost to consumer information about science

00:01:09.320 | and science-related tools to the general public.

00:01:12.000 | In keeping with that theme,

00:01:13.240 | I'd like to thank the sponsors of today's podcast.

00:01:15.920 | Our first sponsor is Helix Sleep.

00:01:18.160 | Helix Sleep makes mattresses and pillows

00:01:20.000 | that are customized to your unique sleep needs.

00:01:22.600 | It's abundantly clear that sleep is the foundation

00:01:25.000 | of mental health, physical health, and performance.

00:01:27.520 | When we're getting enough quality sleep,

00:01:29.200 | everything in life goes so much better,

00:01:30.760 | and when we are not getting enough quality sleep,

00:01:32.920 | everything in life is that much more challenging.

00:01:35.360 | And one of the key things to getting a great night's sleep

00:01:37.520 | is to have the appropriate mattress.

00:01:39.480 | Everyone, however, has slightly different needs

00:01:41.440 | in terms of what would be the optimal mattress for them.

00:01:44.240 | Helix understands that people have unique sleep needs,

00:01:46.720 | and they've designed a brief two-minute quiz

00:01:49.000 | that asks you questions like, do you sleep on your back,

00:01:51.440 | your side, or your stomach?

00:01:52.400 | Do you tend to run hot or cold during the night?

00:01:54.080 | Or maybe you don't know the answers to those questions.

00:01:56.280 | If you go to the Helix site and take that brief quiz,

00:01:58.160 | they'll match you to a mattress that's optimal for you.

00:02:00.640 | For me, it turned out to be the Dusk D-U-S-K mattress.

00:02:03.560 | It's not too hard, not too soft,

00:02:05.000 | and I sleep so much better on my Helix mattress

00:02:07.320 | than on any other type of mattress I've used before.

00:02:09.800 | So if you're interested in upgrading your mattress,

00:02:12.000 | go to helixsleep.com/huberman,

00:02:14.800 | take their brief two-minute sleep quiz,

00:02:16.520 | and they'll match you to a customized mattress for you,

00:02:18.560 | and you'll get up to $350 off any mattress order

00:02:21.800 | and two free pillows.

00:02:23.080 | Again, that's helixsleep.com/huberman

00:02:26.200 | to save up to $350 off and two free pillows.

00:02:29.640 | Today's episode is also brought to us by Woop.

00:02:32.560 | Woop is a fitness wearable device

00:02:34.080 | that tracks your daily activity and sleep,

00:02:36.280 | but also goes beyond that by providing real-time feedback

00:02:39.160 | on how to adjust your training and sleep schedule

00:02:41.360 | to perform better.

00:02:42.800 | I've been working with Woop

00:02:43.640 | on their Scientific Advisory Council

00:02:45.640 | to try and help advance Woop's mission

00:02:47.560 | of unlocking human performance.

00:02:49.520 | As a Woop user, I've experienced the health benefits

00:02:51.580 | of their technology firsthand for sleep tracking,

00:02:53.740 | for monitoring other features of my physiology,

00:02:55.840 | and for giving me a lot of feedback

00:02:57.800 | about metrics within my brain and body

00:03:00.120 | that tell me how hard I should train or not train,

00:03:02.480 | and basically point to the things that I'm doing correctly

00:03:04.860 | and incorrectly in my daily life

00:03:06.600 | that I can adjust using protocols,

00:03:08.560 | some of which are actually within the Woop app.

00:03:11.240 | Given that many of us have goals

00:03:12.540 | such as improving our sleep, building better habits,

00:03:15.320 | or just focusing more on our overall health,

00:03:17.600 | Woop is one of the tools

00:03:18.520 | that can really help you get personalized data,

00:03:20.540 | recommendations, and coaching toward your overall health.

00:03:23.640 | In addition to being

00:03:24.480 | one of the most accurate sleep trackers in the world,

00:03:26.520 | Woop allows you to recover more quickly and fully

00:03:29.060 | from physical exercise and other kinds of stress,

00:03:31.360 | and thereby to train more effectively and sleep better.

00:03:34.360 | If you're interested in trying Woop,

00:03:35.880 | you can go to join.woop.com/huberman today

00:03:39.600 | to get your first month free.

00:03:40.920 | Again, that's join.woop.com/huberman.

00:03:44.280 | Today's episode is also brought to us by Waking Up.

00:03:47.660 | The Waking Up app is a meditation app

00:03:49.640 | that offers hundreds of guided meditations,

00:03:51.880 | mindfulness trainings, yoga nidra sessions,

00:03:54.260 | and more.

00:03:55.100 | I started meditating over 30 years ago.

00:03:57.540 | At that time, there wasn't very much science on meditation,

00:04:00.320 | but by now we know that there's a lot of strong science

00:04:03.240 | supporting the fact that a daily meditation practice

00:04:05.680 | can improve mood, focus, and alertness,

00:04:08.560 | and can reduce stress and improve sleep and overall health.

00:04:11.720 | One thing that I and many others have noticed

00:04:13.560 | is that while meditation is excellent for buffering stress,

00:04:16.480 | it's oftentimes during periods of stress

00:04:19.200 | that we let our meditation practice go.

00:04:21.440 | The Waking Up app overcomes this

00:04:22.920 | by offering meditations of different durations.

00:04:25.000 | So they have some longer ones of 30 to 60 minutes,

00:04:27.700 | but also some much briefer ones, 10, five,

00:04:30.120 | and even one minute meditations

00:04:31.560 | that are known to be effective.

00:04:33.200 | So no matter how busy or stressed you get,

00:04:34.920 | you always make time for your meditation practice.

00:04:37.200 | The fact that they have lots of different types

00:04:38.720 | of meditations and yoga nidra sessions

00:04:40.540 | and non-sleep deep rest protocols

00:04:42.520 | also make sure that your meditations

00:04:44.040 | are kept fresh and interesting.

00:04:45.520 | You never get bored of them.

00:04:46.880 | I personally use the Waking Up app

00:04:48.320 | to do a five to 10 minute meditation

00:04:50.080 | or a non-sleep deep rest protocol,

00:04:52.200 | which is similar to yoga nidra each and every day.

00:04:54.600 | And if I miss a day,

00:04:55.720 | I try and double up the amount of time

00:04:57.220 | that I do NSDR, yoga nidra, or meditation the following day.

00:05:01.080 | Yoga nidra and non-sleep deep rest protocols

00:05:03.400 | can be done essentially any time of day

00:05:05.740 | in order to restore mental and physical vigor.

00:05:08.100 | I'll sometimes do one first thing in the morning

00:05:09.720 | if I wake up and I feel I didn't get

00:05:11.400 | quite enough sleep the previous night.

00:05:13.260 | You can also do yoga nidra or NSDR

00:05:15.400 | in the middle of the night

00:05:16.600 | if you wake up and you're having trouble

00:05:17.920 | falling back asleep.

00:05:19.160 | Sometimes they will allow you to fall back asleep,

00:05:20.960 | and if they don't, you'll still feel more refreshed

00:05:23.480 | than you would have had you been tossing and turning

00:05:25.240 | and worrying about not getting sleep.

00:05:27.400 | So NSDR and yoga nidra are terrific

00:05:29.740 | for both restoring mental and physical vigor

00:05:32.440 | and potentially for restoring sleep

00:05:34.400 | that you otherwise would have missed.

00:05:36.040 | If you'd like to try the Waking Up app,

00:05:37.520 | you can go to wakingup.com/huberman

00:05:40.600 | to get a free 30 day trial.

00:05:42.320 | Again, that's wakingup.com/huberman.

00:05:45.220 | And now for my conversation with Dr. Matthew Walker.

00:05:48.440 | Dr. Walker.

00:05:49.460 | - Dr. Huberman.

00:05:50.760 | Welcome back.

00:05:51.600 | We have covered a lot of material.

00:05:54.080 | First episode of this series,

00:05:56.320 | you gave us an overview of sleep

00:05:58.000 | and some actionable items about sleep.

00:06:00.900 | Then in the second episode,

00:06:02.120 | you gave us far more actionable items

00:06:05.920 | of how to think about one's sleep

00:06:08.300 | in a way that leads to very concrete decisions

00:06:11.940 | about controlling light, temperature, when to sleep,

00:06:15.380 | and then some really in-depth advanced tools

00:06:19.520 | or protocols as we call them.

00:06:21.640 | And then in the third episode,

00:06:23.600 | we talked about caffeine and napping

00:06:27.200 | and some other things that people can do

00:06:28.920 | to really supercharge their alertness

00:06:31.280 | through sleep augmentation in the daytime.

00:06:35.360 | And today we're going to talk about sleep,

00:06:38.700 | learning and memory,

00:06:39.860 | and a topic that I know everybody

00:06:42.240 | is very interested in, creativity.

00:06:44.640 | - Indeed.

00:06:46.160 | Resplendent pleasure to be back on the show.

00:06:48.360 | Thank you for having me.

00:06:49.280 | - Yeah, absolutely.

00:06:50.560 | So I think nowadays most people understand

00:06:54.720 | that there's some relationship between sleep and learning.

00:06:58.280 | But I think it would still be a good idea

00:07:01.080 | for us to zoom out a bit

00:07:02.480 | and establish what that relationship is.

00:07:05.240 | You know, I think most people are familiar

00:07:06.920 | with being exposed to some new material,

00:07:10.080 | cognitive material, physical skill material,

00:07:13.200 | and not being able to learn it right away,

00:07:15.760 | but then having a few days in between.

00:07:18.580 | And then all of a sudden, voila.

00:07:20.800 | - Yeah.

00:07:21.640 | - There's a, the skill has been embedded, it seems.

00:07:25.760 | But not obvious in that scenario

00:07:27.840 | is that sleep is perhaps the pivotal event

00:07:30.400 | that allowed the learning process to take place.

00:07:33.720 | So how do you think about sleep

00:07:35.800 | as it relates to learning and memory?

00:07:38.520 | - I think I've conceptualized it in three different stages

00:07:42.400 | or three different buckets of a benefit.

00:07:45.420 | The first is that we need sleep before learning

00:07:49.920 | to prepare your brain to initially imprint

00:07:54.280 | and lay those memory traces down.

00:07:57.780 | But then you need to sleep after learning

00:08:02.000 | to take those sort of freshly minted memories

00:08:06.120 | and then save them and cement them into the brain

00:08:09.920 | so that you don't lose them.

00:08:12.200 | The third domain is that sleep will then take

00:08:16.620 | those new memories that you've been learning

00:08:19.140 | and it will start to collide them

00:08:21.620 | with all of this back catalog of information

00:08:24.620 | that you've already got stored in your brain.

00:08:27.860 | And it updates the iOS of your informational systems

00:08:32.860 | so that then you come back the next day

00:08:35.940 | and you have a better abled ability

00:08:39.460 | to understand how the world works.

00:08:42.380 | In other words, the difference between knowledge,

00:08:44.220 | which is learning the facts and wisdom,

00:08:47.380 | which is knowing what it all means when you put it together.

00:08:51.340 | That's the third category.

00:08:53.460 | And why is that beneficial?

00:08:55.100 | Because it provides you with creative insights.

00:08:58.940 | And so we will perhaps just double click

00:09:01.340 | on each of those three and I can expand them

00:09:04.460 | because the data behind them is utterly fascinating.

00:09:08.080 | As you said, I think many people subjectively have a sense

00:09:10.740 | that sleep helps me with my memory in some way,

00:09:15.400 | but in what way?

00:09:17.240 | And for people, I think one of the things that you do here

00:09:19.540 | is not just protocols,

00:09:21.100 | but you help explain the conceptual understanding

00:09:25.020 | or the conceptual mechanisms underlying the reasons

00:09:28.940 | for all of these protocols.

00:09:30.220 | And I would love to dive into detail.

00:09:32.620 | - Yeah, so let's do that.

00:09:34.060 | Let's talk about this business of sleeping before learning.

00:09:37.860 | Essentially establishing a milieu within the brain

00:09:41.940 | that is optimal for learning.

00:09:43.540 | What is that about?

00:09:45.400 | Neurochemically at the level of circuits

00:09:48.460 | and what is the evidence that providing some,

00:09:52.380 | I don't know, additional sleep or just adequate sleep

00:09:54.980 | prior to the exposure to the new material

00:09:57.220 | can be beneficial?

00:09:58.940 | - Yeah, I love that word, that optimal milieu

00:10:02.140 | and it beautifully describes what we found.

00:10:04.620 | We started off asking a very simple question

00:10:08.180 | at my sleep center.

00:10:09.740 | Is pulling the all-nighter a wise idea?

00:10:12.820 | So we took a group of perfectly healthy, smart individuals

00:10:18.180 | and we assigned them to one of two experimental groups,

00:10:21.120 | a sleep group and a sleep deprivation group.

00:10:23.680 | And both of those groups

00:10:26.540 | went through those two different protocols.

00:10:28.780 | And then the next day after sleep or after no sleep,

00:10:32.700 | we put them inside of a brain scanner

00:10:35.060 | and we had them try and learn a whole list of new facts

00:10:38.920 | as we were taking snapshots of brain activity.

00:10:42.020 | And then we tested them

00:10:43.540 | to see how effective that learning had been.

00:10:46.540 | When we looked at the group

00:10:48.580 | that had had a full night of sleep,

00:10:50.660 | they had incredibly efficient learning capacity.

00:10:54.300 | So in other words, they had learned

00:10:56.340 | and imprinted that information initially very well.

00:11:00.140 | When we looked at the sleep deprivation group, not so much.

00:11:03.880 | In fact, there was a 40% deficit

00:11:07.260 | in the ability of the brain

00:11:08.900 | to make new memories without sleep.

00:11:12.620 | And we've used lots of different types.

00:11:14.460 | We've replicated that now.

00:11:15.920 | We've had visual information.

00:11:17.580 | We've had textbook-like information.

00:11:19.900 | And the range is somewhere between 20 to 40%.

00:11:24.500 | I find that, by the way, striking

00:11:26.020 | and we can come back to this

00:11:27.860 | based on what we are seeing

00:11:29.420 | in our educational systems right now.

00:11:32.340 | There is this paucity of sleep

00:11:34.420 | because of this model of early school start times.

00:11:37.540 | And I'll explain exactly what's happened there

00:11:39.540 | and what we've been doing to try to change that.

00:11:42.500 | But coming back to those two groups,

00:11:45.180 | the sleep group and the sleep deprivation group,

00:11:47.620 | what was going on, as you said, inside of the brain

00:11:51.100 | that would help us understand why they couldn't learn

00:11:54.740 | or at least couldn't learn effectively?

00:11:57.100 | And the structure that we focused on

00:11:58.780 | is one you've spoken about before called the hippocampus.

00:12:01.780 | And you have one on the left side

00:12:03.920 | and the right side of your brain.

00:12:05.040 | It looks like a long cigar that runs down

00:12:07.540 | the left and right side of your brain.

00:12:10.180 | And people listening can think of the hippocampus

00:12:12.580 | almost like the informational inbox of your brain.

00:12:15.660 | It's very good at receiving new memory files

00:12:18.360 | and then holding onto them.

00:12:20.300 | And when we looked at that structure

00:12:21.780 | and its activity during learning in the sleep group,

00:12:24.840 | they had wonderful, powerful activation of the hippocampus

00:12:28.580 | as if it was gobbling up all of that new information

00:12:31.120 | into the inbox.

00:12:32.360 | When we looked at the sleep deprivation group, however,

00:12:35.580 | we couldn't find any significant signal whatsoever.

00:12:39.400 | So it was almost as though sleep deprivation

00:12:43.100 | had shut down the memory inbox and any new incoming files,

00:12:47.460 | they were just being bounced.

00:12:49.180 | You couldn't effectively commit new experiences to memory.

00:12:53.860 | And then subsequent studies that were not done by us,

00:12:56.740 | but looking at animal models,

00:12:59.340 | they were looking at how able the synapses are

00:13:03.960 | in that memory structure, the hippocampus,

00:13:06.500 | how capable those synapses are for building new connections.

00:13:11.300 | And the synapses are just those connections between neurons.

00:13:14.020 | And we think that part of the way that we make memories

00:13:17.300 | is by strengthening the connection

00:13:19.700 | in the memory circuit itself.

00:13:22.500 | And what they found was that when they restricted the sleep

00:13:26.280 | of these rats or the mice,

00:13:28.300 | that part of the brain became very stubborn.

00:13:31.940 | It just wouldn't form those new synaptic connections.

00:13:35.540 | And something that we call synaptic plasticity.

00:13:38.200 | So we started to understand this was the bad that happened

00:13:43.500 | when you take sleep away.

00:13:46.020 | But let's come back to that control group

00:13:47.940 | that I said got a full night of sleep.

00:13:50.380 | Exactly what is it about sleep when you do get it

00:13:54.060 | that seems to support and promote your learning ability?

00:13:57.240 | So we decided to do another different study.

00:14:00.920 | Instead of manipulating sleep by dialing it down,

00:14:04.220 | we instead tried to dial it up by way of a daytime nap.

00:14:08.680 | And again, we took two groups

00:14:10.460 | and we had them initially learn, again,

00:14:12.980 | a huge amount of factual information.

00:14:15.500 | They learned it over and over and over again.

00:14:18.340 | And then we brought them back six hours later at 6 p.m.

00:14:23.340 | and now we had them learn a whole new set of information.

00:14:28.140 | And after each one of those fresh novel learning sessions,

00:14:31.700 | we tested them to see how effective

00:14:33.620 | that learning had been again.

00:14:35.060 | One of those groups spent that six hours of time awake,

00:14:40.140 | doing just relaxing activities.

00:14:42.580 | The other group was able to obtain a 90 minute nap.

00:14:46.740 | And we use that 90 minute nap to allow them

00:14:48.620 | to go through a full sort of average cycle

00:14:51.220 | to get some non-REM and to get some REM.

00:14:53.220 | What was interesting is that when we tested the group

00:14:57.140 | that remained awake later that following day,

00:15:00.260 | the learning capacity had declined.

00:15:03.340 | But in the nap group,

00:15:06.260 | it seemed to restore the brain's capacity to learn.

00:15:10.260 | And you didn't get that decline in memory.

00:15:13.140 | In fact, if anything, you got a little boost.

00:15:15.140 | And the difference between those two was about 20%.

00:15:18.620 | Just quite a nice benefit.

00:15:20.340 | - Yeah, not trivial.

00:15:21.340 | - Not trivial at all.

00:15:23.500 | And then we said, okay, well, if sleep is doing something,

00:15:26.540 | what is it about that sleep?

00:15:28.660 | So we unpacked the physiology of sleep

00:15:30.980 | and the different stages of sleep

00:15:32.420 | that we discussed in the first episode.

00:15:34.740 | And what we found was that it was

00:15:36.740 | the non-rapid eye movement sleep or the non-REM sleep.

00:15:40.300 | And particularly those sleep spindles,

00:15:42.300 | those short bursts of electrical activity

00:15:44.660 | that we have discussed before,

00:15:47.020 | that seemed to predict how restored

00:15:50.460 | and refreshed your learning ability was.

00:15:53.260 | And the best way that I've been thinking about this

00:15:57.700 | in terms of sleep restoring

00:15:59.380 | or refreshing your encoding ability,

00:16:02.540 | and it's a crass analogy,

00:16:03.780 | and I don't mean to make a direct brain-to-computer analogy,

00:16:06.540 | but think of that hippocampus almost like a USB stick.

00:16:10.980 | That's very good during the day

00:16:12.500 | at going around and grabbing new files,

00:16:15.220 | but it has a limited storage capacity.

00:16:18.460 | And what sleep was doing seemed to be

00:16:21.020 | shifting those memories from the USB stick

00:16:24.660 | of your hippocampus over up to the cortex,

00:16:28.060 | which you can think of almost like your hard drive,

00:16:29.740 | a much bigger storage capacity.

00:16:31.820 | And by way of doing that,

00:16:33.060 | when you woke up after the nap

00:16:34.900 | or after a full night of sleep,

00:16:36.980 | you had this cleared out USB stick.

00:16:39.220 | So what could you do?

00:16:40.220 | You could go around

00:16:41.300 | and start acquiring all these new files again.

00:16:44.380 | So that started to teach us a little bit about

00:16:48.540 | why sleep before learning is critical,

00:16:51.300 | but also mechanistically how sleep

00:16:54.060 | is doing this remarkable work of memory restoration.

00:16:58.260 | We then wanted to say,

00:17:00.380 | well, can we translate this out into the real world?

00:17:04.260 | And I think there are two regions

00:17:06.380 | that we've moved this work out into.

00:17:07.860 | One is education, one is medicine and Alzheimer's disease.

00:17:11.580 | But the education piece was very interesting.

00:17:14.940 | In the United States, I think the last time I checked,

00:17:18.220 | the average school start time

00:17:20.500 | is somewhere around 7.30, 7.45.

00:17:23.980 | - Sounds about right.

00:17:25.460 | - And if you think about that for 7.30 school start times,

00:17:29.420 | school buses will begin leaving

00:17:32.060 | around 5.30, 5.45 in the morning.

00:17:36.220 | That means that some kids are having to wake up

00:17:38.580 | at 5 a.m., maybe even earlier.

00:17:42.340 | This is lunacy when you think about it.

00:17:45.420 | And there's a great study in Edna,

00:17:47.620 | I hope I'm pronouncing that correct, Edna,

00:17:49.700 | which is a small suburb or it sits in a small suburb

00:17:52.460 | outside of Minneapolis in Minnesota.

00:17:55.140 | And they shifted their school start times

00:17:57.420 | from 7.25 to 8.30 in the morning.

00:18:01.940 | And then they wanted to ask what is the consequence of that

00:18:05.500 | on the academic performance of their students?

00:18:08.380 | And the metric that they used in these teenagers

00:18:11.340 | that they were focusing on

00:18:12.340 | was something called the SAT score,

00:18:14.660 | which is a score I had to learn

00:18:16.260 | when I first came to the United States,

00:18:17.940 | is a critical assessment test

00:18:20.780 | that will largely determine which university you go to.

00:18:24.180 | And they did an analysis which was clever.

00:18:27.020 | They focused on the top 10% performing students,

00:18:31.540 | which you could argue,

00:18:32.740 | those are the ones that are closest

00:18:34.420 | to the ceiling performance

00:18:36.140 | and the hardest to expect any benefit from sleep.

00:18:40.060 | So in the year before they made the time change,

00:18:43.100 | the average score of those top 10% performing students

00:18:46.700 | was 1,288, which turns out to be a pretty good SAT score.

00:18:51.700 | The following year after they made the time change,

00:18:56.100 | the average score for that top 10% was 1,500.

00:19:02.100 | That difference is non-trivial

00:19:05.940 | and it will change exactly where those individuals

00:19:10.220 | will go to university

00:19:11.660 | in terms of the tier of the university

00:19:13.260 | and likely change the trajectory of their lives

00:19:16.220 | as a consequence.

00:19:18.020 | Now, some people have argued that data,

00:19:20.100 | in terms of its source and its reliability

00:19:23.620 | may not have necessarily been accurate,

00:19:25.420 | but now we've got very consistent data.

00:19:28.860 | When you start school times later,

00:19:32.100 | academic grades improve,

00:19:34.300 | psychological and psychiatric problems decrease,

00:19:38.100 | truancy rates decrease.

00:19:40.700 | But something else happened in that story

00:19:43.500 | of later school start times that we didn't expect,

00:19:46.620 | which was that the life expectancy of students increased.

00:19:50.660 | And you think, well, hang on a second,

00:19:52.300 | how do you determine that?

00:19:54.820 | The number one cause of death in teenagers 16 to 18

00:19:59.820 | is actually not suicide, it turns out to be second,

00:20:03.980 | it's road traffic accidents.

00:20:06.460 | And here sleep matters enormously.

00:20:09.140 | There was another great example

00:20:10.420 | from Teton County in Wyoming,

00:20:13.380 | and they shifted their school start times

00:20:15.500 | from I think it was 7.35 in the morning to 8.55.

00:20:19.820 | And the only thing more remarkable

00:20:21.180 | than the extra one hour of sleep

00:20:22.780 | those kids reported getting was the drop in car accidents.

00:20:26.980 | That following year, there was a 70% reduction

00:20:30.940 | in car crashes in that age range of 16 to 18.

00:20:34.620 | - What time are they getting out of school?

00:20:36.460 | - Well, they will probably be ejected out of school.

00:20:39.300 | That's another interesting part, by the way,

00:20:41.220 | maybe around 4.30.

00:20:43.540 | And people have said, well, look,

00:20:46.340 | all of this idea of later school start times,

00:20:50.980 | it means that it's going to cost us more

00:20:52.940 | 'cause you've got to change the school bus system.

00:20:55.220 | And they've argued pushback against that.

00:20:58.100 | And I would say probably two things.

00:21:00.740 | First, I know it's difficult,

00:21:02.860 | and I'm not saying it's an easy problem to do,

00:21:04.860 | it's a complex problem.

00:21:06.780 | And I'm sympathetic to that.

00:21:08.700 | But I think we've put people on the moon.

00:21:11.820 | And so I suspect that we can also solve the problem

00:21:14.620 | of early school start times.

00:21:18.660 | The other component of that is

00:21:20.940 | what are we doing as educators?

00:21:25.380 | If our goal as educators is truly to educate

00:21:30.300 | and not risk lives in the process,

00:21:33.380 | then we are failing our children

00:21:35.340 | in a most spectacular manner

00:21:37.780 | with this incessant model of early school start times.

00:21:41.700 | And if you look at the data, it's very clear.

00:21:44.540 | When sleep is abundant, minds flourish.

00:21:48.780 | And when it's not, they don't.

00:21:51.260 | And so that's the reason why myself

00:21:54.100 | and a whole group of sleep scientists,

00:21:56.380 | we started to try to create a movement

00:21:58.660 | for later school start times.

00:22:00.340 | And we got this bill passed firstly in California,

00:22:03.780 | and we got it on the governor's desk at the time.

00:22:06.180 | It was Governor Brown.

00:22:07.940 | And unfortunately, he didn't sign it into law.

00:22:11.300 | Then when the organization changed

00:22:14.700 | and Governor Newsom came in as governor of California,

00:22:17.820 | we got the bill back on his desk and he did sign it.

00:22:21.380 | And then the next state to go was New York.

00:22:24.500 | They started to put in legislation

00:22:26.900 | for recommendations for later school start times.

00:22:28.860 | I think Florida is about to fall as well in that regard.

00:22:33.180 | So there's gradual movement happening,

00:22:36.620 | but it's hard fought and it's problematic.

00:22:41.620 | I still think that it's impossible to deny that data.

00:22:46.340 | I mean, it was an interesting thing.

00:22:47.940 | I remember when I was a professor back at Harvard,

00:22:51.420 | we were doing this work on sleep and learning.

00:22:55.580 | And they said, and it was sort of published

00:22:57.580 | in these sort of kindly, I don't know how we did it,

00:23:00.540 | but in nice journals.

00:23:01.820 | And they said, okay, based on the media attraction,

00:23:05.180 | would you write an editorial for the Harvard newspaper,

00:23:07.420 | which was called the Harvard Crimson?

00:23:08.700 | And I said, I'd love to.

00:23:10.260 | So at first I thought I'm just going to write a straight

00:23:12.620 | piece about sleep and memory and why it's important.

00:23:15.180 | And I realized, no, there's a better opportunity

00:23:17.180 | because teaching there, and you know this as well as I do,

00:23:21.180 | there is this bizarre system where we teach

00:23:23.700 | for an entire semester and then we end load the semester

00:23:27.020 | full of exams in this stressful two week period.

00:23:31.220 | And what do you think is going to happen?

00:23:33.180 | They're not going to sleep, especially at a time

00:23:36.380 | when they're trying to cram information.

00:23:38.820 | - So especially in college where you don't actually

00:23:40.980 | have the material four weeks before.

00:23:43.620 | So there's not really the option to learn it in advance.

00:23:46.620 | - No.

00:23:47.460 | - Everything's about university to me.

00:23:49.260 | It was about getting a bunch of information

00:23:51.980 | and needing to incorporate it very quickly

00:23:53.860 | and then move to the next item.

00:23:55.620 | - Right, next item, next item.

00:23:57.020 | And then all of a sudden there's this cataclysmic moment

00:23:59.980 | at the end of the semester,

00:24:01.220 | and you are supposed to regurgitate this

00:24:03.140 | by cramming everything into your brain

00:24:05.540 | in this sleepless two week period.

00:24:08.140 | So rather than saying, look,

00:24:10.060 | the students need to change their behavior,

00:24:11.940 | they need to understand this is a problem.

00:24:14.540 | It's not their fault.

00:24:16.140 | I said, it's us as educators and administrators.

00:24:20.260 | We have created a system that forces them

00:24:24.260 | to undergo deliberate sleep deprivation,

00:24:26.860 | and we are educating them amnesic, quite literally.

00:24:31.620 | So I put this editorial out.

00:24:35.540 | It received a rather Baltic, if not Arctic response.

00:24:40.540 | And that was the last editorial I was ever invited

00:24:45.380 | to write for the newspaper.

00:24:47.940 | But you've got to say your piece.

00:24:51.340 | - Well, so, but I'm curious why there's resistance

00:24:54.300 | to shifting to later school times

00:24:56.300 | and to improving the conditions for learning

00:24:59.700 | if the goal is to learn.

00:25:01.380 | I mean, tradition dies hard.

00:25:03.900 | Maybe that's why.

00:25:04.820 | I think there's also the idea,

00:25:06.980 | certainly in the medical profession,

00:25:08.300 | that, well, when I was doing my training,

00:25:11.140 | we would pull all-nighters all the time.

00:25:13.140 | And so the idea then is that it's just part

00:25:16.140 | of the self-directed hazing process,

00:25:18.540 | that is getting a degree,

00:25:20.300 | that you're going to be doing a lot of all-nighters

00:25:22.260 | and cramming and things of that sort.

00:25:24.260 | Is that what you think motivates the resistance to change?

00:25:27.500 | - I think so.

00:25:28.340 | I think you've hit all the points.

00:25:29.220 | I think, you know, zeitgeists die one generation at a time,

00:25:33.660 | and we see that resistance certainly there too.

00:25:37.820 | I also think that when you come back

00:25:40.900 | to later school start times,

00:25:42.380 | they have suggested that there is this cost

00:25:47.980 | when they tally it up.

00:25:49.340 | But you made a point,

00:25:50.180 | which is when did they get out of school?

00:25:51.740 | And let's say it's around 4.30.

00:25:54.300 | One of the interesting analyses that was published,

00:25:56.660 | and we latched onto this,

00:25:58.940 | that is this strange bewitching hour

00:26:02.660 | when kids get out of school,

00:26:04.900 | but often their parents are not home to work.

00:26:07.980 | And if you look at the teenage crime rate,

00:26:11.580 | and you look at when those crimes are committed,

00:26:14.180 | it's usually in that bewitching hour

00:26:16.620 | after they get out of school,

00:26:18.220 | but they don't have a home or parents yet

00:26:21.100 | to go to that it's filled.

00:26:23.220 | But by pushing school start times later,

00:26:25.820 | they get out later, they go home.

00:26:29.020 | And if you were to even half that debt

00:26:31.700 | that those crimes cause,

00:26:34.260 | you would easily pay for the education system.

00:26:38.420 | So it's very interesting.

00:26:40.420 | I think that also notion of,

00:26:43.380 | well, we went through it and here I am,

00:26:46.780 | so you can go through it too,

00:26:48.140 | is very prevalent in medicine.

00:26:49.860 | This is another good example.

00:26:52.380 | We and mostly colleagues at mine,

00:26:55.260 | such as Charles Seisler at Harvard,

00:26:57.180 | have really done a great job

00:26:58.620 | at cataloging exactly why we need

00:27:00.740 | to abandon this resident program,

00:27:03.220 | which has a fascinating history, by the way,

00:27:05.580 | which is young residents should be working 30-hour shifts

00:27:10.620 | often without any sleep whatsoever.

00:27:13.140 | And when you look at that data,

00:27:14.620 | residents who are working a 30-hour shift

00:27:17.420 | are going to be almost 460% more likely

00:27:20.180 | to make diagnostic errors in the intensive care unit.

00:27:23.300 | If you have a surgeon and you're getting elective surgery

00:27:27.100 | who's had less than six hours of sleep in the previous 24,

00:27:32.100 | they are almost 70% more likely to cause a surgical error,

00:27:37.180 | which could result in non-trivial consequences.

00:27:41.900 | And then the irony is that when young residents

00:27:44.700 | after a 30-hour shift get back into their car

00:27:48.300 | at the end of the shift and drive home,

00:27:50.540 | there is 168% increased risk

00:27:53.580 | that they get into a car accident

00:27:55.340 | and then end up back in the ER from where they just came,

00:27:59.460 | but now as a patient rather than a physician.

00:28:02.340 | And you think, what are we doing?

00:28:05.340 | Charles Seisler, I think, has described,

00:28:07.780 | they provided this evidence to the council.

00:28:12.140 | And at first they just, I think the idea was,

00:28:15.380 | look, our minds are made up,

00:28:17.460 | don't confuse me with the data.

00:28:19.140 | And when you appeal on the empathetic basis,

00:28:23.100 | but it wasn't well-received.

00:28:25.940 | So then if you go back and you say,

00:28:28.020 | no, I'm going to give you a different argument.

00:28:29.900 | If you look at the cost of malpractice

00:28:31.940 | caused by insufficient sleep,

00:28:34.140 | and if you get the administrators into the room,

00:28:36.660 | all of a sudden the schedules change.

00:28:38.940 | So then based on that data,

00:28:40.740 | there was a policy that you couldn't work any longer

00:28:43.380 | than I think it was a 16 hour continuous shift.

00:28:46.460 | The problem was that they only said

00:28:49.940 | that that was apparent for the first year residents

00:28:52.820 | and not the remaining years.

00:28:54.460 | And the question was, well, why?

00:28:56.220 | I said, well, the data that you showed us,

00:28:58.060 | you only collected in first year residents.

00:29:00.940 | As if something magical was going to happen

00:29:03.380 | when you become a second year resident

00:29:05.220 | and you don this Teflon coat of immunity

00:29:08.580 | against sleep deprivation.

00:29:09.820 | - Well, if anything, it would compound and get worse.

00:29:11.660 | So it seems to me that there's like zero question

00:29:16.660 | that getting adequate sleep is good for learning,

00:29:22.460 | but when the stakes,

00:29:23.620 | when it's high risk, high consequences scenarios,

00:29:26.180 | or even high consequences scenarios,

00:29:27.660 | like a medical situation,

00:29:31.460 | just seems like it should almost come down

00:29:33.620 | to legal liability.

00:29:34.940 | - Yeah.

00:29:36.020 | - I'd like to take a brief break

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00:29:56.900 | I strive to get those foods mostly from unprocessed

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00:30:05.820 | So with AG1, I ensure that I get enough

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00:30:14.260 | to eat fruits and vegetables.

00:30:15.580 | And in that way, provide a sort of insurance

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00:30:19.380 | In addition, the adaptogens

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00:30:49.020 | So are the errors of sleep deprivation in these scenarios,

00:30:54.020 | both in students and medical professionals,

00:30:58.300 | are they due to errors in memory per se?

00:31:02.180 | I mean, 'cause you can imagine all sorts of errors.

00:31:04.540 | So with the surgeon, they like cut the wrong thing

00:31:06.900 | or they cut too far,

00:31:07.860 | the margin on the surgical side is too big, et cetera.

00:31:11.060 | But since we're talking about learning and memory

00:31:13.580 | and its relationship to sleep,

00:31:16.260 | is it that people are forgetting what they did?

00:31:18.980 | Are they forgetting what they didn't do?

00:31:20.500 | I mean, or is it a deficit in motor skills

00:31:23.940 | or all of the above?

00:31:25.100 | - It's all of the above plus,

00:31:27.540 | which is that learning and memory,

00:31:29.180 | your recollection of both what you did

00:31:31.860 | or what you need to do

00:31:33.460 | or what you should do based on your training

00:31:35.380 | is going to be compromised

00:31:36.500 | because your recall of that information,

00:31:38.260 | it turns out is also compromised.

00:31:40.460 | But it's also decision-making too,

00:31:42.540 | that what we know is that your frontal lobe

00:31:44.940 | is especially sensitive to a lack of sleep.

00:31:48.060 | And it's that frontal lobe

00:31:49.140 | that really takes complex situations,

00:31:51.700 | distills them down and comes up

00:31:53.780 | with the correct output scenario of decisions

00:31:56.860 | that you need to make.

00:31:58.180 | Not so much when you're sleep deprived.

00:32:00.940 | - So how should I establish the proper neural milieu

00:32:05.940 | for learning by sleeping prior?

00:32:08.700 | Should I make sure that I,

00:32:09.980 | I mean, in an ideal world,

00:32:10.940 | I get an excellent night's sleep for the,

00:32:13.300 | you know, every day of my life

00:32:15.380 | leading up to a bout of learning.

00:32:17.540 | And here I'm referring to a bout of learning

00:32:18.940 | as being exposed to new material,

00:32:20.540 | but life happens.

00:32:24.460 | So if I know that tomorrow I'm going to take a class

00:32:28.020 | in something, or I'm going to need to perform a skill

00:32:32.460 | that it's pretty nascent skill for me,

00:32:34.380 | I've only learned it recently.

00:32:36.460 | What should I do the night before?

00:32:38.180 | - I would say, think about what you can get

00:32:42.620 | in terms of your sleep under current conditions

00:32:46.100 | and understand that that is staying awake

00:32:51.100 | and foregoing sleep is not the right equation

00:32:55.580 | that you may think.

00:32:57.020 | In other words, think of sleep that night

00:33:00.260 | as an investment in tomorrow

00:33:02.740 | rather than a cost opportunity of now or today.

00:33:06.780 | That would be the message I think for learning and memory.

00:33:10.220 | Some people will say logically and rationally,

00:33:13.300 | well, but if I stay awake,

00:33:15.580 | I can at least be learning

00:33:17.180 | and going over that material for many more hours.

00:33:20.180 | So doesn't that compensate for me going to bed?

00:33:24.780 | Let's say I haven't learned it well enough.

00:33:26.460 | Well, surely I should just say,

00:33:29.180 | I should just focus and stay awake

00:33:31.780 | 'cause at least then I can just go over the material

00:33:34.140 | time and time and time again.

00:33:35.540 | Doesn't that offset the deficit?

00:33:38.540 | And to a degree it does, we did that study.

00:33:40.780 | But what was really interesting is that the next day

00:33:43.900 | were you able to at least learn

00:33:46.860 | and recall some of that information to a degree?

00:33:49.700 | Yes, you were.

00:33:51.220 | And the more that you kept going over it,

00:33:53.380 | the better you performed

00:33:55.820 | even when you were not getting sufficient sleep.

00:33:57.860 | But then we did something interesting.

00:33:59.540 | We then brought them back.

00:34:00.700 | We haven't published this data, I should do.

00:34:02.940 | We brought them back a month later

00:34:05.780 | and then we tested them again.

00:34:08.100 | And what you find is that the group that slept

00:34:11.340 | was far better able to have retained

00:34:14.620 | and remember that information.

00:34:17.100 | Whereas the group that did not sleep as much,

00:34:20.780 | they performed much more similar to the group

00:34:23.980 | that got a full night of sleep the next day.

00:34:26.660 | But when you test them a month later,

00:34:29.500 | almost none of that material

00:34:32.020 | is residing in their brain anymore.

00:34:33.740 | - Got it.

00:34:34.580 | So this is the cramming effect.

00:34:36.340 | - That's right.

00:34:37.180 | - Right, and one knows this from teaching university courses

00:34:41.620 | or if they've crammed that you can learn a bunch of material

00:34:43.980 | but then you regurgitate it for the exam

00:34:46.820 | and then it's gone.

00:34:47.780 | - Yeah.

00:34:48.660 | - So it's almost like a,

00:34:50.660 | it just never passes from short-term

00:34:52.300 | to long-term memory essentially.

00:34:53.900 | - That's correct.

00:34:54.940 | And that seems to be in some ways

00:34:57.020 | that's a beautiful description of then what happens next

00:35:00.060 | in the sleep process.

00:35:00.900 | It's not just about sleep before learning.

00:35:03.740 | You then have to sleep after learning

00:35:05.860 | to do exactly what you just described.

00:35:08.740 | - So I have a class in the morning

00:35:13.060 | or I'm going to learn something new the next day afternoon.

00:35:17.260 | My goal presumably should be

00:35:19.300 | to maximize the amount of sleep I get

00:35:22.180 | and to be on the same sleep schedule.

00:35:25.540 | So this gets back to QQRT

00:35:27.220 | that was presented in the first episode,

00:35:29.580 | quantity, quality, regularity, and timing.

00:35:32.900 | And people should refer to that.

00:35:34.780 | - Nothing wrong with your memory, by the way.

00:35:36.380 | - Well, I don't know about that,

00:35:37.580 | but the QQRT formula was described in the first episode.

00:35:44.180 | Let's come up with what I think

00:35:46.580 | is a fairly common scenario.

00:35:47.860 | So I like to go to bed early between eight and 9 p.m.

00:35:51.260 | I discovered this recently,

00:35:52.540 | thanks to conversations with you.

00:35:53.700 | This is clearly what works best for me.

00:35:55.180 | I kind of always intuit it,

00:35:56.260 | but it clearly is what works best.

00:35:58.940 | If I go to bed at 10,

00:36:01.340 | I probably want to wake up sometime around 6 a.m. or 6.30.

00:36:05.580 | And if I go to bed any later than 10.30,

00:36:08.860 | I start running into problems.

00:36:09.900 | I don't feel good the next day,

00:36:11.140 | even if I get sufficient hours of sleep.

00:36:13.340 | So this is the importance of regularity and timing,

00:36:15.420 | keeping things more or less locked

00:36:16.620 | to that 8.30 to 9.30 to bedtime for me,

00:36:19.820 | 4.30 to 5.30 wake up time.

00:36:21.380 | That's me, just by way of example.

00:36:24.660 | In an ideal world, therefore,

00:36:26.460 | I would stick to that schedule,

00:36:28.820 | wake up the next day and go do my learning

00:36:31.500 | or my performance of something that I'd learned.

00:36:33.140 | Someone else might have the chronotype,

00:36:35.060 | we're going to bed at 11 p.m.

00:36:36.380 | and waking up at 7.30 a.m. is their preferred schedule.

00:36:40.340 | However, often because of travel, because of courses,

00:36:44.940 | because of life circumstances,

00:36:46.620 | the night before something critical that we need to learn

00:36:51.460 | or to perform some critical task, physical or cognitive,

00:36:55.420 | the sleep the night before is disrupted in some way,

00:36:58.100 | either by virtue of timing or quantity.

00:37:01.300 | And then of course, by extension, regularity.

00:37:03.460 | So is there anything that we can do

00:37:06.940 | heading into a bout of learning,

00:37:09.260 | meaning the night preceding that bout of learning

00:37:11.740 | that can kind of provide a buffer

00:37:15.780 | or set us up for the best possible learning scenario

00:37:18.700 | if we're not able to stick to our perfect schedule?

00:37:22.060 | - I think there may be two things.

00:37:23.620 | There's been a little bit of work that's been done

00:37:26.980 | to suggest that caffeine may actually enhance

00:37:30.380 | the hippocampus, this memory encoding structure

00:37:34.060 | and boost its ability to encode.

00:37:37.020 | Now, what they haven't yet done is the study

00:37:39.980 | where you sleep deprive someone,

00:37:42.260 | then you give them caffeine the next day,

00:37:44.540 | and then you have them try to learn and ask,

00:37:47.020 | can caffeine by way of its effect on the hippocampus

00:37:50.060 | rescue and restore

00:37:52.580 | what would otherwise be an encoding deficit?

00:37:55.740 | Now, that is entirely possible.

00:37:57.700 | I think it's a fascinating question.

00:37:59.460 | By how much, we don't know.

00:38:03.500 | But if it doesn't, it's equally likely

00:38:05.700 | that the hippocampus by way of being sleep deprived

00:38:10.260 | is not receptive to the benefit of caffeine

00:38:13.380 | under conditions of sleep deprivation.

00:38:15.300 | And I told you in the rat studies,

00:38:17.460 | when those rats were deprived,

00:38:19.380 | the hippocampus once again became stubborn

00:38:22.620 | in its ability to form new synapses.

00:38:25.300 | And it may be that it's equally stubborn

00:38:27.420 | to receive the normal benefit of caffeine

00:38:30.460 | when you are sleep rested.

00:38:32.420 | But I would love to do that study.

00:38:34.580 | The second is to then say,

00:38:35.780 | well, if I have the choice

00:38:37.780 | of when I'm going to be learning during the day,

00:38:40.500 | let's say that you've had a bad night of sleep

00:38:42.140 | or you just had a short night of sleep,

00:38:43.700 | non-negotiable, couldn't do anything about it.

00:38:46.060 | And the next day I've got to cram in some information.

00:38:49.300 | I would say, think about your chronotype

00:38:52.500 | and think about when you are

00:38:54.260 | at your best operating temperature.

00:38:56.820 | So your scenario, let's say going to bed at nine,

00:39:01.180 | waking up at 4.30, five,

00:39:03.340 | your peak is probably going to be maybe 10, 11 o'clock

00:39:07.540 | in the morning where your biology

00:39:09.060 | and your circadian rhythm is on its almost crescendo peak.

00:39:13.300 | At that point, we know for circadian influences on learning,

00:39:18.180 | and this is independent of sleep influences on learning,

00:39:20.700 | that's where things are better.

00:39:21.940 | Now, for me, you actually described me,

00:39:23.620 | which is I'm a kind of an 11 to 7.30 type person.

00:39:27.300 | For me, it's probably going to be much closer

00:39:29.060 | to about midday or 1 p.m.

00:39:31.620 | where I feel at my operating peak,

00:39:33.940 | both for physical performance and also mental performance.

00:39:37.620 | So if you've got the choice and you are underslept,

00:39:40.860 | there's nothing you can do about the sleep

00:39:42.420 | that you've lost the night before,

00:39:44.180 | but at least recognize that your circadian rhythm

00:39:46.620 | is going to come to your rescue and help offset that

00:39:50.340 | as long as you time your learning

00:39:52.820 | to that known peak of your circadian rhythm.

00:39:56.780 | Does that help a little bit?

00:39:57.860 | - Yes, that makes good sense.

00:39:59.780 | So the idea gets us back to something

00:40:03.020 | you described in previous episodes,

00:40:04.740 | which is that you have this sleep pressure

00:40:06.660 | due to the buildup of the molecule adenosine,

00:40:08.740 | which the longer we're awake,

00:40:10.580 | the more adenosine in our nervous system,

00:40:12.700 | which makes us sleepy.

00:40:14.180 | But separate from that, there's this circadian circadia,

00:40:19.180 | about 24-hour rhythm, right,

00:40:21.620 | that causes fairly dramatic shifts

00:40:26.820 | in wakefulness and sleepiness,

00:40:29.260 | independent of the adenosine signal.

00:40:31.180 | Now, sometimes the two signals overlap,

00:40:33.420 | so that late in the evening, for instance,

00:40:35.260 | we have a lot of adenosine, we've been up all day,

00:40:37.060 | and our circadian rhythm is such

00:40:38.380 | that our alertness is starting to diminish,

00:40:40.460 | so they're aligned.

00:40:41.300 | And in the early part of the day,

00:40:42.220 | assuming everything is normal,

00:40:43.540 | the adenosine levels are low

00:40:45.140 | because we slept well the night before,

00:40:46.420 | and our circadian rhythm is on the upswing, so to speak,

00:40:49.780 | and we are alert.

00:40:52.380 | So if I understand correctly,

00:40:54.460 | the goal is to, of course,

00:40:56.900 | maximize the quality, quantity, regularity,

00:40:59.180 | and timing of sleep, QQRT,

00:41:01.300 | but that in the absence of the ability

00:41:04.220 | to really anchor any one of those things

00:41:07.660 | to 10 out of 10, A-plus performance,

00:41:11.100 | if one knows that, okay, typically around,

00:41:13.940 | between 10 a.m. and noon is when I'm at my sharpest,

00:41:16.500 | that would be the time to be exposed to new material,

00:41:19.060 | or ideally take an exam,

00:41:20.380 | if one can control that sort of thing.

00:41:22.580 | And then perhaps in the afternoon,

00:41:24.340 | there's another opportunity after the postprandial dip.

00:41:29.340 | - That's right.

00:41:30.620 | - But before the postprandial dip,

00:41:32.740 | sometime between one and four p.m.,

00:41:34.060 | usually lasting about an hour to 90 minutes,

00:41:35.940 | this is a natural dip in energy,

00:41:37.500 | but then after that is another opportunity to learn.

00:41:42.000 | Sure, there'll be a lot of adenosine in one system

00:41:44.940 | 'cause you've been up a long time,

00:41:46.660 | but the circadian system is on its sort of upswing again

00:41:52.540 | before the downswing that occurs in the evening.

00:41:55.100 | Is that right?

00:41:55.940 | - That's right, so you've got two opportunities.

00:41:58.460 | And by the way, it's strange, you were to ask,

00:42:00.220 | if you look at the circadian rhythm,

00:42:02.380 | right before sort of bedtime,

00:42:04.460 | there is this sort of strange little blip,

00:42:06.900 | this peak that folks back at Harvard have discovered.

00:42:11.860 | And you think, well, why would my circadian system,

00:42:14.660 | which needs to really ratchet down

00:42:17.220 | for us to get to sleep well,

00:42:20.120 | why would it have this little jag upwards

00:42:24.260 | in the evening hours, right before we need to sleep,

00:42:27.700 | and it then drops precipitously?

00:42:30.940 | Makes no sense until you think about evolution,

00:42:34.860 | because after foraging for food during the day,

00:42:38.460 | what you need is this final spurt

00:42:41.860 | to get you home safely to your nest or to your home.

00:42:46.860 | - To batten down the hatches.

00:42:48.500 | - Exactly, so there is this beautiful little

00:42:51.640 | built-in circadian upswing to say,

00:42:54.840 | okay, I know you're returning to home.

00:42:56.840 | This is probably a time when there's some

00:42:59.120 | maybe potential threat to you.

00:43:01.280 | I'm gonna just boost your alertness very quickly.

00:43:03.640 | So you travel home safely, good to go, great.

00:43:07.120 | And now I start my downswing.

00:43:09.440 | - I think this is a really important thing

00:43:11.000 | for people to know about.

00:43:13.160 | I'm familiar with the data, although just in top contour,

00:43:16.360 | but the idea here, as I understand it,

00:43:18.500 | is that many people will feel like,

00:43:21.940 | okay, around 6 p.m., 6.30, they're getting sleepy,

00:43:24.780 | 7.30, 8.00 p.m., and then they wanna get to bed at 10.30,

00:43:27.940 | and suddenly, for them, based on their chronotype,

00:43:31.520 | around 9.00 p.m., they're wide awake.

00:43:33.180 | - Second wind. - Right, the second wind,

00:43:34.980 | and they're like, oh no, I need to sleep tonight.

00:43:38.160 | Now, maybe it's the case that they would be better off

00:43:41.320 | going to bed far earlier and waking up earlier

00:43:44.080 | the next morning, but in many cases,

00:43:46.240 | it's just that transient 45 to 60, you know,

00:43:50.020 | 70-minute window of increased alertness.

00:43:53.980 | - That's right. - This kind of uptick

00:43:56.020 | in the circadian alertness system.

00:43:58.020 | - Yeah, this too shall pass, and then also,

00:44:00.980 | just set yourself up for success,

00:44:02.780 | and we discussed a little bit about the methods

00:44:04.620 | of really ratcheting things down, dimming down the lights,

00:44:08.300 | having a to-bed alarm.

00:44:09.960 | These types of things will just gradually back you off,

00:44:13.420 | and after that second wind comes,

00:44:15.980 | give you the greatest ability to decline physiologically,

00:44:20.440 | which then permits this beautiful thing called sleep

00:44:23.540 | to come in its place.

00:44:25.280 | - Well, speaking of sleep post-learning,

00:44:27.660 | what is the role of sleep that follows about learning?

00:44:32.020 | And here, again, we wanna define learning

00:44:33.760 | as the exposure to novel information

00:44:37.240 | that one is trying to encode,

00:44:38.460 | either cognitive information, motor information,

00:44:40.540 | or a combination of the two.

00:44:43.260 | And I say that because learning, a.k.a. neuroplasticity,

00:44:47.460 | has many different stages.

00:44:48.740 | It's a process, not an event.

00:44:51.020 | So, let's say that earlier in the day,

00:44:53.400 | I took a dance class, Lord knows I need one,

00:44:55.980 | or-- - You and I both.

00:44:57.780 | - Or a musical lesson,

00:44:59.020 | or was exposed to some interesting information,

00:45:01.280 | who knows, maybe on a podcast,

00:45:03.020 | and I was trying to engage in that information

00:45:05.460 | and pay attention, and then that night, I planned to sleep,

00:45:10.000 | or perhaps one could take a nap

00:45:11.820 | after this bout of learning.

00:45:13.940 | How close to the learning episode,

00:45:19.660 | about, as I'm calling it, does the sleep have to arrive

00:45:22.540 | in order for sleep to maximize

00:45:24.220 | the amount of learning that occurs?

00:45:26.780 | - It's a very good question, which is,

00:45:28.680 | what would happen if I were to be learning information

00:45:33.180 | and I'm listening to this odd British gentleman,

00:45:37.060 | should I then immediately dive into bed

00:45:39.980 | so that I maximize the retention of that information?

00:45:44.180 | And the answer is no, don't worry.

00:45:46.940 | I'll come back to why not to worry,

00:45:49.780 | but to your point,

00:45:51.380 | not only do you need sleep before learning,

00:45:53.460 | as we've been discussing,

00:45:55.300 | but there is something unique and equally necessary of,

00:45:59.820 | and causally necessary, I should say,

00:46:02.020 | for sleep after learning, but it does something different.

00:46:05.380 | Sleep before learning gets your brain ready

00:46:07.720 | to lay down those new memory traces.

00:46:10.460 | After you've imprinted them into the brain,

00:46:12.660 | sleep after learning then takes those

00:46:15.580 | freshly minted memories and then it strengthens them.

00:46:20.580 | Essentially, it's almost like sleep will hit

00:46:22.460 | the save button on those new memories

00:46:25.260 | so that you don't forget.

00:46:27.060 | So in other words, sleep is future-proofing

00:46:30.220 | that information within your brain

00:46:32.820 | so that you don't forget.

00:46:35.520 | And then the question, and we've been able to,

00:46:37.800 | and we and many others have replicated this,

00:46:39.940 | in fact, it's nothing new.

00:46:41.640 | If you look at the literature

00:46:43.280 | on this sleep after learning gig,

00:46:46.760 | it goes back, as best we can tell, to 1929.

00:46:52.360 | Although, I'll argue with that in a second,

00:46:55.160 | but two researchers, Jenkins and Dallenbach,

00:46:57.880 | did a landmark study.

00:47:00.000 | They had participants learn

00:47:01.880 | a whole bunch of nonsense syllables

00:47:04.240 | and they had them learn them over and over and over again

00:47:07.260 | and gradually they got better.

00:47:09.120 | And then they started to test them

00:47:11.400 | across an eight-hour period.

00:47:13.200 | They tested them two hours later, four hours later,

00:47:16.040 | six hours later, and eight hours later.

00:47:18.540 | The only difference is that in one of those testing sessions

00:47:22.380 | that two hours, four hours, six hours, eight hours

00:47:25.140 | was across a waking day.

00:47:27.100 | In the other, they had them learn that information

00:47:30.380 | to near perfection before sleep,

00:47:32.380 | just as they did in the waking group,

00:47:34.140 | but now they woke them up after two hours and tested them,

00:47:36.900 | after four hours and tested them,

00:47:38.280 | just six hours, and then again,

00:47:40.260 | when they woke up in the morning, eight hours later.

00:47:42.740 | And what they found is that in those people

00:47:44.300 | who stayed awake after learning,

00:47:47.180 | there was essentially just catastrophic forgetting.

00:47:50.720 | The amount of information, two hours, four hours,

00:47:53.180 | six hours, eight hours later, just declined dramatically.

00:47:57.000 | But when they repeated that in the same individuals

00:48:00.140 | after learning things to the same degree,

00:48:02.980 | two hours, four hours later,

00:48:04.500 | memory was starting to decline.

00:48:06.020 | But after about two and a half, three hours of being asleep,

00:48:10.300 | all of a sudden, sleep had fixated those memories

00:48:13.940 | almost like an animal that's been trapped in ember

00:48:18.620 | and set in ember like a fossil.

00:48:21.020 | And then those memories just would not decay any further

00:48:23.660 | and you retained them.

00:48:24.780 | What was stunning about that study

00:48:27.500 | is it has been replicated time and time again.

00:48:31.920 | That's not the surprising part.

00:48:33.680 | The surprising part is that in that study,

00:48:35.900 | they tested a vast number of subjects.

00:48:38.540 | In fact, a sum total of two participants.

00:48:41.920 | (laughs)

00:48:43.940 | But what's stunning is that that finding has gone

00:48:47.180 | and been replicated time and time again.

00:48:49.420 | So that demonstrated to us

00:48:52.060 | that there's something special about sleep

00:48:54.700 | that is concretizing, almost literally,

00:48:57.780 | like taking things and setting it in concrete.

00:49:01.140 | And then the question became, again, mechanistically, how?

00:49:05.100 | How is it?

00:49:06.100 | And it's important to understand mechanism

00:49:07.780 | because it has ramifications for diseases and medicine.

00:49:10.600 | How is sleep doing this fantastic saving of memories?

00:49:14.940 | And we now have at least two

00:49:16.940 | non-mutually exclusive mechanisms.

00:49:19.580 | So in other words, both seem to occur.

00:49:22.340 | The first is what we call memory translocation.

00:49:27.560 | Sleep and particularly what we found for fact-based memories.

00:49:31.400 | And I should note, by the way,

00:49:32.440 | that this story of sleep after learning is a two-part

00:49:36.680 | or it runs in two different narratives.

00:49:39.500 | One is sleep after learning for fact-based memory,

00:49:43.920 | what we describe as declarative memory.

00:49:46.920 | And you've done a fantastic previous episode

00:49:50.280 | on working memory and describe

00:49:52.120 | all of these different types of memory.

00:49:54.560 | So one story line has been sleep after learning

00:49:57.380 | for fact-based memory.

00:49:58.240 | But the other, which is equally interesting,

00:50:01.120 | is sleep for non-declarative or procedural skill memory.

00:50:05.600 | In other words, what we think of as motor memory.

00:50:08.200 | But I'll come back to motor memory in a second.

00:50:10.660 | What we then found for this sleep and textbook-like memory

00:50:15.360 | is that there are two mechanisms.

00:50:16.600 | The first, translocation.

00:50:18.120 | And here, what we found is that it's deep non-REM sleep

00:50:21.720 | for fact-based memories.

00:50:23.800 | And it's those big, slow, powerful brainwaves

00:50:27.140 | that we spoke about in the first episode,

00:50:29.120 | combined with those sleep spindles

00:50:31.240 | that ride on top of them almost like a surfer

00:50:34.080 | on a huge amplitude wave.

00:50:36.360 | And it's the combination of those two brainwaves

00:50:41.440 | that acts like a file transfer mechanism.

00:50:45.200 | And it moves and shifts memories

00:50:47.440 | from a short-term vulnerable reservoir, the hippocampus,

00:50:51.160 | to the more permanent long-term storage site,

00:50:54.000 | the cortex in the brain,

00:50:55.800 | and therefore protecting them and making them safe.

00:50:59.240 | So that's one mechanism,

00:51:01.520 | is the shifting of memories around the brain

00:51:04.320 | and through different storage sites

00:51:06.120 | from short-term to long-term.

00:51:07.560 | The second, I think, is perhaps even more fascinating.

00:51:11.880 | It's called memory replay.

00:51:15.000 | And this was discovered back in the probably 1990s.

00:51:18.720 | Bruce McNaughton at the University of Arizona

00:51:21.400 | working with a young Matt Wilson, who not,

00:51:24.160 | I'm Matt Walker, he's Matt Wilson at MIT now.

00:51:27.240 | They were looking at rats

00:51:28.680 | and they were looking at how rats learn a maze.

00:51:32.000 | And they had these electrodes

00:51:34.320 | in these hippocampal brain regions,

00:51:38.200 | these memory-related regions that we've been discussing.

00:51:41.440 | And they were listening to the individual firing patterns

00:51:45.240 | of those memory cells in the hippocampus

00:51:47.520 | as they were running around the maze.

00:51:49.080 | And sure enough, as they ran around the maze,

00:51:51.400 | statistically, you would build up

00:51:53.200 | what looked like the signature pattern of learning.

00:51:55.960 | So think about those neurons,

00:51:57.800 | that they each had a special tone to them.

00:52:00.240 | And as the rat is running around the maze,

00:52:02.040 | you can hear the signature of learning.

00:52:03.840 | Ba-ba-ba-ba, ba-ba-ba-bum, ba-ba-ba-bum, ba-ba-ba-bum.

00:52:07.280 | I just went over and over again.

00:52:09.000 | But then they did something clever.

00:52:10.880 | When the rats went to sleep after learning,

00:52:14.360 | they kept listening.

00:52:15.360 | What did they hear?

00:52:17.200 | They didn't just hear noise.

00:52:18.920 | They heard that same memory signature replayed.

00:52:22.240 | However, it wasn't replayed at the same speed.

00:52:27.040 | It was replayed somewhere between 10 to 20 times faster.

00:52:32.040 | So now, all of a sudden, instead of hearing ba-ba-ba-bum,

00:52:35.520 | ba-ba-ba-bum, you heard brum, brum, brum, brum, brum, brum,

00:52:39.800 | just going over and over again.

00:52:41.720 | And what we've learned is that this replay of memories

00:52:44.920 | for that type of information.

00:52:46.720 | Now, for rats, that their version, essentially,

00:52:49.560 | of that spatial navigation is their version

00:52:52.480 | of fact-based memory.

00:52:53.560 | And I won't go into detail, but-

00:52:55.160 | - Yeah, 'cause navigating novel environments

00:52:58.040 | is especially important for all species,

00:53:01.040 | but rodents, to know where they cached food,

00:53:03.760 | where escapes are, and things of that sort.

00:53:05.600 | - Yeah, perhaps even more so than us humans,

00:53:07.960 | that locational memory is necessary.

00:53:09.440 | - And nowadays, there's Google Maps,

00:53:11.080 | and Uber, and things of that sort.

00:53:12.640 | But in the old days, as it were, I recall,

00:53:16.000 | the London taxi drivers were considered

00:53:18.560 | the world heavyweight champions of memory.

00:53:23.560 | And there were some decent brain imaging studies

00:53:27.080 | of their hippocampi.

00:53:29.200 | And indeed, they have amazing spatial memory

00:53:31.360 | of the city of London.

00:53:33.200 | Now, that's probably changed because of Google Maps.

00:53:36.200 | There's no need to rely on internal memory stores

00:53:39.680 | when you have-

00:53:40.520 | - No, you still actually, there's still a...

00:53:42.320 | Now, you can drive these rideshare apps,

00:53:45.440 | but for London taxi drivers,

00:53:46.880 | they still have to go through,

00:53:47.920 | in some ways, it's almost like a hazing,

00:53:49.640 | it's called the knowledge.

00:53:51.600 | And if you are visiting London,

00:53:54.320 | you will see these strange guys

00:53:56.040 | who are going around on mopeds,

00:53:58.200 | and they just have this huge kind of map in front of them.

00:54:01.960 | And they are doing the knowledge,

00:54:03.880 | which is that they are learning exquisitely

00:54:06.120 | the entire roadmap of London.

00:54:08.560 | And what they found in those studies

00:54:10.520 | was that the size of the hippocampus,

00:54:13.720 | this memory structure related to fact-based memories

00:54:16.280 | and also spatial memories,

00:54:17.680 | was significantly larger in cab drivers

00:54:21.800 | than it was in matched controls.

00:54:24.120 | Now, you could say, well,

00:54:24.960 | this is a self-selecting process

00:54:27.040 | that people who already have large hippocampi,

00:54:31.320 | as we would say,

00:54:32.720 | they're just going to be the people

00:54:34.000 | who can do the knowledge well and pass, as it were.

00:54:37.120 | But what they also found was that a correlation,

00:54:39.920 | the longer that you've been doing the knowledge

00:54:42.560 | and being a taxi driver,

00:54:44.600 | the bigger and bigger your hippocampus,

00:54:46.440 | so it's time on task.

00:54:48.640 | So coming back to the rats and this spatial learning,

00:54:52.440 | it's almost as though sleep after learning

00:54:55.440 | is taking that memory trace,

00:54:57.280 | and it's like etching into a glass surface.

00:55:00.520 | You just go over that memory circuit over and over again,

00:55:04.000 | and you're strengthening that memory circuit.

00:55:06.680 | What was also fascinating, however,

00:55:10.400 | I'm telling you that it's during non-REM sleep

00:55:12.760 | that you do all of this memory replay.

00:55:15.680 | And certainly what we found is that for textbook memory,

00:55:18.280 | it's deep non-REM sleep.

00:55:19.640 | That's the important stage of sleep.

00:55:21.720 | But Matt Wilson published at MIT an interesting study

00:55:25.120 | looking at REM sleep.

00:55:27.000 | What happens to the memory trace in REM sleep?

00:55:30.400 | And REM sleep, which we know is associated with dreaming,

00:55:34.480 | that the memory replay didn't slow back down

00:55:38.040 | to normal waking speed.

00:55:39.800 | It slowed down even further to 0.5 times

00:55:44.800 | relative to waking speed.

00:55:46.400 | So the waking speed versus the dreaming speed.

00:55:49.840 | In dreaming, sort of in REM sleep, I should say,

00:55:52.600 | because we don't know if rats dream or not,

00:55:54.200 | but in REM sleep, things had slowed down by essentially 50%.

00:55:59.200 | And this comes back to our conversation

00:56:01.320 | in a previous episode that we had about time.

00:56:04.640 | And you and I were discussing

00:56:05.800 | how there's this strange phenomenon

00:56:07.360 | where you are woken up by your alarm and you're in a dream

00:56:11.320 | and you have a snooze button that lasts five minutes.

00:56:13.560 | You hit the snooze button, you go back to sleep

00:56:15.440 | and you feel as though you've been dreaming

00:56:17.040 | for 10 minutes, 15 minutes.

00:56:20.440 | But it's been five minutes in the real world,

00:56:22.520 | but time has slowed down, time has dilated.

00:56:25.480 | It's almost like a concertina that's stretched out.

00:56:29.000 | And all of a sudden we were finding in,

00:56:31.160 | or Matt Wilson, because we don't do animal research,

00:56:33.160 | was finding that this replay was slowed down by 50%.

00:56:38.160 | So I always wonder whether or not there is neuronal evidence

00:56:42.240 | that helps us explain why dreams seem to pack more time,

00:56:46.880 | despite being in real world time, a shorter amount.

00:56:50.520 | Absolutely fascinating.

00:56:52.600 | - Yeah, I have to imagine that rats dream

00:56:57.200 | and dogs dream and other animals dream.

00:56:59.320 | I mean, why wouldn't they?

00:57:02.760 | If all the components of REM sleep

00:57:05.160 | that are expressed in humans appear in these animals

00:57:08.320 | and vice versa, you imagine it almost has to be the case.

00:57:12.040 | - It does.

00:57:12.880 | And I think there is some interesting supportive evidence

00:57:15.120 | that you can argue.

00:57:16.200 | There is a sleep disorder that we understood in humans first

00:57:20.440 | called rapid eye movement disorder

00:57:23.280 | or REM sleep behavioral disorder.

00:57:26.320 | And in the first episode,

00:57:27.880 | we said that one of the fascinating features of REM sleep,

00:57:31.400 | which is when we principally dream,

00:57:34.120 | is that your brain and specifically your brainstem

00:57:37.520 | paralyzes your body so that your mind can dream safely.

00:57:41.640 | So you're shut down

00:57:43.280 | into this motor paralysis incarceration, rightly so.

00:57:48.280 | But what also happens is that as we get older

00:57:52.560 | and it seems to be particularly more so in men

00:57:54.840 | than in women, but it can be both.

00:57:56.840 | Once we get past our fifties,

00:57:58.200 | there's a higher likelihood

00:57:59.960 | that that mechanism starts to degrade

00:58:04.000 | and you can start to act out your dreams.

00:58:06.240 | Now, this is not sleep walking or sleep talking.

00:58:08.840 | That actually comes from deep non-REM sleep.

00:58:12.360 | And there, what happens is that there is a trigger,

00:58:14.760 | an awakening, either a brain response,

00:58:17.320 | almost like a stress response that wakes the brain up

00:58:20.440 | and you're in the deepest stages of sleep.

00:58:22.760 | And you are trying to get forced back up to wakefulness.

00:58:26.280 | So back to that analogy of going from the basement

00:58:29.000 | to the penthouse.

00:58:30.880 | And instead you just get locked

00:58:32.720 | into this mixed state of consciousness.

00:58:35.080 | And as a consequence,

00:58:37.680 | you start to enact very rote, basic behaviors.

00:58:41.280 | You'll go over to the refrigerator, open the door,

00:58:43.480 | close the door, pick up a glass, put it to your mouth,

00:58:45.800 | put it back down.

00:58:47.480 | And if you wake someone up,

00:58:49.160 | which you shouldn't necessarily do unless there's harm,

00:58:52.840 | and ask them, what was going through your mind

00:58:55.440 | just a few minutes ago?

00:58:56.640 | They'll say nothing.

00:58:58.120 | And the reason is because it wasn't coming from dream sleep,

00:59:00.560 | it was from deep non-REM sleep.

00:59:02.120 | - I see.

00:59:03.040 | - However, there is a very different condition

00:59:05.480 | that sometimes people will mix up as the very same thing,

00:59:09.200 | which is REM sleep behavioral disorder.

00:59:10.920 | And there you're acting out your dreams.

00:59:12.400 | It can be quite violent.

00:59:13.800 | Some people have enacted violence on their partner

00:59:16.520 | and woken up and been absolutely devastated.

00:59:19.240 | I bring this up, however,

00:59:21.400 | because human beings are not the only species

00:59:23.880 | that suffers from REM sleep behavioral disorder.

00:59:27.280 | Dogs suffer from this as well.

00:59:29.960 | And when you see it and you can understand it,

00:59:32.000 | it's very clear, you have electrodes on the head,

00:59:34.440 | they go into this REM sleep state,

00:59:36.080 | and all of a sudden they come out of the paralysis

00:59:39.400 | and they start enacting what very much looks like

00:59:43.200 | a behavior of wakefulness.

00:59:45.800 | It's quite complex.

00:59:47.360 | And at that point, you look at that and you say,

00:59:50.920 | okay, I'm sorry, but that looks very much like dreaming.

00:59:54.600 | Now we can't, of course, ask dogs,

00:59:57.760 | question what was going through your mind.

00:59:59.840 | - You can ask them, but they're not gonna answer.

01:00:01.680 | - But yeah, you can ask them,

01:00:03.160 | but it turns out that the response is less than,

01:00:06.440 | it's just a look to say, give me a treat.

01:00:08.440 | But in science, sometimes if it looks like a duck,

01:00:11.800 | talks like a duck, walks like a duck, maybe it's a duck.

01:00:14.920 | - What about this phenomenon,

01:00:18.680 | which I've experienced before of being asleep,

01:00:22.360 | presumably in rapid eye movement sleep

01:00:24.680 | and being completely paralyzed,

01:00:26.040 | but then waking up and I'm still in paralysis,

01:00:29.960 | but I'm not asleep.

01:00:32.600 | And this was a long time ago, probably the 10th grade,

01:00:37.320 | which for me, I was what, 15 years old, I'm 48 now,

01:00:41.120 | and was at a party that I fell asleep on the couch.

01:00:44.760 | And goodness, I don't believe in underage drinking,

01:00:48.240 | but there's a possibility

01:00:49.680 | that I might've been inebriated.

01:00:51.380 | - It's just a possibility.

01:00:52.920 | - Kids, parents, I actively dissuade young people

01:00:57.920 | from drinking and many older people from drinking,

01:01:00.980 | but yeah, I started drinking far too young.

01:01:03.760 | And, but I remember I drank the night before,

01:01:06.520 | I got drunk the night before,

01:01:08.120 | again, something I'm not suggesting or proud of.

01:01:11.800 | I woke up and I was wide awake.

01:01:14.920 | Gosh, I remember this so well.

01:01:16.240 | And I was paralyzed, I could not move.

01:01:18.240 | And it was terrifying.

01:01:19.880 | And then all of a sudden, boom, I could jolt myself awake.

01:01:23.200 | And I was like, oh my goodness.

01:01:24.600 | And it must've been an invasion of that atonia,

01:01:28.380 | that sleep induced paralysis into the waking state.

01:01:31.720 | - So I can explain this and you have,

01:01:34.920 | this is the perfect prototypical situation when we see this.

01:01:39.440 | What you're describing to me is something

01:01:41.480 | that many people listening will have experienced

01:01:43.520 | called REM sleep paralysis.

01:01:46.200 | And it's not necessarily a problem

01:01:48.480 | or a sign of a condition that you need to be worried about.

01:01:51.400 | Although if it's happening frequently,

01:01:52.920 | we can think about that.

01:01:55.240 | What normally happens when we wake up out of REM sleep

01:01:58.000 | and REM sleep, as we spoke about in the first episode,

01:02:00.240 | dominates the second half of the night

01:02:02.080 | and particularly the last quarter of the night.

01:02:05.040 | As you're coming out of REM sleep

01:02:06.880 | and waking up out of REM sleep,

01:02:08.240 | which you've got a 50, 50% chance perhaps,

01:02:11.000 | 'cause the other state that you're in

01:02:12.160 | is stage two light non-REM.

01:02:14.360 | As you're coming out of REM sleep,

01:02:15.960 | you're regaining consciousness to the external world.

01:02:19.400 | And then normally in lockstep with that perfect lockstep,

01:02:23.080 | if not a little before,

01:02:24.680 | your brain is realizing this

01:02:26.760 | and it's releasing you from the paralysis.

01:02:28.880 | And we all wake up and we don't even think about it.

01:02:31.400 | I just wake up and I lean over,

01:02:33.880 | I turn off the alarm and I get out of bed.

01:02:36.520 | Everything's fine.

01:02:38.080 | Every now and again, however,

01:02:40.040 | the waking up and consciousness re-engaging occurs.

01:02:45.360 | However, the brain does not release you

01:02:48.080 | from the REM sleep paralysis.

01:02:50.120 | So at that point,

01:02:51.560 | it's almost like a locked in body phenomenon.

01:02:54.640 | And it's very frightening

01:02:55.640 | because you begin to be aware of your surroundings,

01:02:59.120 | but you cannot make any voluntary movements.

01:03:02.040 | Because I told you

01:03:02.880 | that the voluntary skeletal muscle system

01:03:05.040 | is impaired by the atonia, the absence of muscle.

01:03:07.960 | You're involuntary, you're still breathing and all that.

01:03:10.080 | But your eyelids turn out to be part

01:03:12.480 | of your voluntary muscle set.

01:03:16.240 | So you can't lift up your eyelids.

01:03:19.160 | And then normally what happens

01:03:20.880 | is that it's associated with a strong sense

01:03:24.360 | of often an intruder, it seems to be.

01:03:27.360 | If you're doing it sort of in bed by yourself at home,

01:03:30.840 | now your context was a little different.

01:03:33.240 | And it turns out that if you look

01:03:36.120 | at these descriptions of sleep paralysis

01:03:38.320 | where you can't wake up, you can't shout out,

01:03:41.320 | you can't move, you have this sense of another presence

01:03:44.000 | or another being in the room,

01:03:46.000 | it adequately explains most,

01:03:48.200 | if not all alien abduction stories.

01:03:51.360 | Because when was the last time you saw a news article

01:03:54.920 | or on the news that someone said,

01:03:57.000 | okay, today it was very clear that Jimmy in Wisconsin

01:04:01.200 | in the middle of the day was abducted by aliens

01:04:03.840 | and everyone saw it.

01:04:05.400 | You know, you're at the meeting table and whoosh,

01:04:07.960 | what happened?

01:04:09.000 | That was Jimmy just got whisked off by alien.

01:04:11.720 | It doesn't happen that way.

01:04:13.080 | It's normally that you're in bed at night.

01:04:16.000 | It's the early morning hours just before you're waking up.

01:04:19.280 | These aliens came into the room,

01:04:20.880 | they injected something into you, they paralyzed you.

01:04:24.000 | You couldn't shout, you couldn't move.

01:04:26.000 | It's simply REM sleep paralysis.

01:04:29.120 | Now, when do we see that?

01:04:30.800 | There are ways and not ways

01:04:33.400 | because these are not protocols that we advise.

01:04:36.160 | There are circumstances where the probability

01:04:38.720 | of that increases.

01:04:39.760 | And I've experienced this too.

01:04:41.480 | When you are sleep deprived or you are highly stressed,

01:04:45.840 | the likelihood that you will experience

01:04:48.120 | these REM sleep paralysis events

01:04:50.200 | upon awakening is increased.

01:04:52.640 | And for me, it was happening when I was a young PhD student

01:04:57.640 | and I was studying sleep.

01:04:59.840 | And then I would be awake all night

01:05:02.480 | 'cause I'd be monitoring the patients

01:05:04.000 | and looking at their sleep.

01:05:05.600 | - The irony of sleep studies.

01:05:07.080 | - Exactly, that you have to deprive yourself

01:05:08.920 | of the very thing that you are trying to study.

01:05:11.520 | Which by the way, gives you some amazing insights

01:05:14.760 | for experiments that I've had as a consequence,

01:05:16.520 | not that I would advise that as the way.

01:05:18.880 | And we'll come on to why that's not wise

01:05:21.400 | when we speak about creativity.

01:05:22.760 | But we were doing these studies and then I would go home

01:05:27.360 | and then I would take a short period of sleep,

01:05:29.880 | maybe just two and a half hours of sleep.

01:05:33.920 | And then I would wake up, I didn't want to

01:05:36.440 | 'cause I was ready to go deep into sleep,

01:05:38.640 | but I would wake up and then I would force myself

01:05:41.600 | to be awake throughout the day

01:05:42.600 | and try to get to bed at a reasonable time.

01:05:44.760 | Because if I slept all day, what's gonna happen?

01:05:46.960 | I'm just gonna be awake all the next night

01:05:48.680 | and I'm gonna be out of my rhythm.

01:05:50.800 | But what's interesting is that when I would wake up then,

01:05:53.520 | I would be waking up maybe at 10 a.m. in the morning, 11.

01:05:57.000 | And at that point, if you're sleeping there

01:05:58.880 | with someone like my face,

01:06:00.240 | you are in a very REM sleep desiring state

01:06:05.240 | that it's in those last morning hours

01:06:08.120 | and into the early morning hours

01:06:09.640 | when your brain wants to devour off the menu of sleep stages,

01:06:13.160 | this thing called REM in vast quantities.

01:06:15.680 | So I was sleep deprived, point number one.

01:06:18.840 | Second, I was going into a very REM sleep rich phase,

01:06:21.800 | in other words, higher likelihood of paralysis.

01:06:24.320 | And that occurred to me.

01:06:25.360 | Your description is also prototypical.

01:06:28.080 | You've been drinking the night before,

01:06:30.520 | went out to the party.

01:06:32.280 | We spoke about in one of our previous episodes

01:06:35.040 | that one of the problems with alcohol

01:06:36.760 | is that it's very good at blocking your REM sleep.

01:06:39.440 | So you'd been absent of REM sleep the prior night,

01:06:42.360 | you'd built up what we call a REM sleep debt.

01:06:46.160 | And when you slept, all of a sudden,

01:06:48.440 | what your brain wanted more,

01:06:50.120 | because it at least got some sleep

01:06:51.920 | and there you're going to get mostly your deep sleep.

01:06:54.480 | The debt on the sheets of your balance account for sleep

01:06:58.280 | was not so great for deep non-REM,

01:07:00.880 | but you were very much in debt with REM.

01:07:03.160 | So what happened as soon as you conked out on the couch,

01:07:06.360 | whoosh, you were probably straight into REM sleep.

01:07:09.120 | And then when you woke up,

01:07:10.360 | you had this mismatch in timing between consciousness

01:07:13.160 | and the release of paralysis.

01:07:14.640 | What did you experience?

01:07:16.000 | REM sleep paralysis.

01:07:17.560 | - Love it.

01:07:18.560 | I mean, hate it.

01:07:19.680 | I did not enjoy it, but I love your description.

01:07:22.600 | It's 'cause it makes so very clear what happened.

01:07:24.520 | And for those that have had the experience,

01:07:26.120 | it can be mildly stressful to terrifying.

01:07:29.500 | So thank you for providing the therapy that is knowledge

01:07:34.240 | and so that people don't stress it too much,

01:07:37.280 | but we still dissuade people

01:07:38.440 | from consuming alcohol prior to sleep.

01:07:40.600 | - Correct.

01:07:41.880 | - I want to take a brief break

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01:08:46.640 | Okay, so we've been discussing complete paralysis,

01:08:49.800 | and of course that's the inability to move.

01:08:53.200 | Let's talk about the ability to move,

01:08:56.540 | meaning motor learning.

01:08:59.360 | What is the relationship between sleep

01:09:01.920 | and learning physical skills,

01:09:03.500 | either coordination of motor movement,

01:09:05.400 | or who knows, maybe increased power output or endurance?

01:09:10.400 | And if you would, could you comment on whether or not

01:09:14.100 | there are specific phases of sleep

01:09:15.660 | that are specifically linked to motor learning?

01:09:18.680 | - Yeah, great question.

01:09:19.880 | So what we've spoken about so far

01:09:22.300 | is that you need sleep after learning

01:09:24.320 | for that textbook-like memory,

01:09:26.200 | and that is one category of memory

01:09:28.320 | that resides within your brain.

01:09:30.320 | There's another type of memory that you've spoken about,

01:09:32.680 | which many of us don't realize is memory,

01:09:35.320 | and that's what we call non-declarative

01:09:37.280 | or procedural skill memory.

01:09:39.680 | So if I were to ask you,

01:09:41.920 | "Okay, Andrew, last night for dinner

01:09:45.440 | or yesterday for lunch,

01:09:46.960 | do you remember what it was that you had to eat?"

01:09:51.720 | My guess is that you could probably tell me.

01:09:53.760 | So do you recall what some of that food was?

01:09:57.280 | - My diet's pretty boring.

01:09:59.000 | In a sense, I tend to eat more or less

01:10:00.560 | the same thing every day,

01:10:01.520 | although I'm open to being flexible.

01:10:03.960 | Yesterday for lunch, I had two grass-fed hamburger patties,

01:10:08.960 | maybe a little bit of rice,

01:10:11.960 | a sliced cucumber, some tomatoes,

01:10:14.120 | and because I'm a drive-by blueberry eater,

01:10:17.200 | there were some blueberries out on the counter,

01:10:19.180 | and I had several large fistfuls of those.

01:10:22.440 | And then I washed it down with some water

01:10:24.640 | and a half mug, just like this,

01:10:28.040 | of some cold brew, sugar-free yerba mate.

01:10:32.040 | - And I can confirm, folks, I was there at the incident,

01:10:34.480 | and that's exactly what he had.

01:10:36.320 | But did everyone who was watching or listening

01:10:39.560 | just realize what happened in this room today?

01:10:43.440 | Something that Einstein suggested would never be possible,

01:10:47.400 | that Andrew just traveled back in time,

01:10:50.320 | that using this incredible gift of memory,

01:10:55.040 | you folded time, almost like a concertina, compressing it,

01:11:00.040 | and you raced back, within milliseconds,

01:11:02.300 | you were shaking your head, "Yes, I know what I had,"

01:11:05.200 | and you raced back into that catalog

01:11:07.520 | of all of your previous lunches.

01:11:10.080 | You found the correct manila folder

01:11:12.400 | for that specific lunch, all of the details,

01:11:15.960 | and out it popped.

01:11:18.040 | That is a spectacularly complex computational process

01:11:21.760 | that your brain's memory system

01:11:24.360 | accomplished within milliseconds.

01:11:27.240 | It's stunning what we have as this gift of memory.

01:11:30.940 | But as I said, there's another type of memory.

01:11:33.100 | So if I were to ask you, "Okay, how do you ride a bike?"

01:11:38.100 | It's very difficult.

01:11:39.860 | There is no textbook for, "Here is how to ride a bike."

01:11:43.680 | The way that you do it when you're a child

01:11:45.560 | is that you are taught how to learn

01:11:49.480 | how to ride a bike by being on it.

01:11:52.000 | So if I were to say, "How," 'cause I'm a long-time cyclist,

01:11:54.820 | "How do I take a right turn with my bicycle?"

01:11:59.340 | The obvious suggestion would be,

01:12:00.540 | "Well, you turn the handlebars."

01:12:02.400 | If you turn the handlebars at 30 miles an hour

01:12:04.740 | trying to go around a right bend,

01:12:06.940 | you're gonna crash very quickly.

01:12:09.080 | What in fact you do is you alter the steering angle

01:12:11.680 | just a little, but you lean.

01:12:13.820 | And that is what we call non-declarative,

01:12:17.320 | meaning you can't declare to me what it is that you know.

01:12:21.080 | You just have to show me through action and behavior.

01:12:24.120 | This is skill learning.

01:12:25.620 | And we use it for things like sports,

01:12:28.240 | surgical procedures, flying planes.

01:12:31.280 | There are so many musical performance as well,

01:12:35.040 | so many aspects.

01:12:36.760 | So we wanted to then say,

01:12:38.520 | "Well, sleep is helpful after learning

01:12:40.560 | "for fact-based memory,

01:12:42.220 | "but what about this other type of memory?"

01:12:45.040 | And in truth, I didn't come up with the idea.

01:12:48.220 | It was given to me back in the, gosh, I'm aging myself.

01:12:52.920 | In the early 2000s, I was back in the UK

01:12:55.080 | and I gave a lecture for the decade of the brain,

01:12:58.160 | which it was back then.

01:12:59.720 | And at the end of the course,

01:13:00.880 | I'd spoken a little bit about sleep

01:13:02.720 | and this informational processing,

01:13:05.240 | but no evidence for motor skill memory.

01:13:07.360 | And this gentleman, lovely gentleman,

01:13:10.240 | old gentleman with a sort of a white beard,

01:13:12.400 | I remember his tweed jacket, this green hue, it was beautiful

01:13:16.360 | and he came up to me at the end and he said,

01:13:18.380 | "Look, I'm a musician, I'm a pianist.

01:13:21.000 | "And I was fascinated by what you said about sleep.

01:13:24.340 | "Sometimes I'll sit down and I'm learning a new piece

01:13:27.720 | "and I just don't seem to be able to get it.

01:13:30.240 | "And I practice, practice and practice into the evening

01:13:33.040 | "and then I just stop."

01:13:35.120 | And then I come back the next day

01:13:36.720 | and I sit down at the piano and I can just play.

01:13:40.840 | Do you think that's sleep?

01:13:43.400 | And of course, at that moment,

01:13:46.040 | my mind starts just rolodexing with ideas

01:13:49.760 | and I'm thinking, gosh,

01:13:50.760 | there's the next 10 years of my work and grants.

01:13:53.680 | And so I sort of said,

01:13:55.280 | look, I think it's a fascinating hypothesis.

01:13:58.080 | It could also be that you're just maybe a little bit tired

01:14:01.320 | in the evening, but it's entirely possible.

01:14:04.480 | I don't know of any evidence yet that supports that.

01:14:07.520 | - I suppose the alternative hypothesis

01:14:09.640 | that there's simply a certain amount of time

01:14:12.200 | that needs to elapse after experiencing something new

01:14:15.040 | that one wants to learn.

01:14:16.440 | The trigger for learning is, I don't know,

01:14:18.080 | some biochemical slash neural signal.

01:14:22.680 | That's like a wave front

01:14:23.720 | and it takes a while for that wave to go ashore,

01:14:26.080 | which is learning.

01:14:27.680 | And that independent of how much sleep one gets

01:14:29.960 | or the quality of sleep, the learning could occur.

01:14:32.640 | I suppose that's one idea.

01:14:34.440 | - No, that's in fact precisely the central hypothesis

01:14:37.240 | that we then set out to test,

01:14:39.240 | which is that maybe it's practice,

01:14:43.440 | then some time that helps you create

01:14:47.120 | that perfect motor routine.

01:14:49.280 | That's one hypothesis, but let's split that apart.

01:14:52.480 | Maybe it's time, but time spent awake,

01:14:55.480 | or is it time, but time spent asleep?

01:14:58.480 | So we designed a study to disambiguate between those two.

01:15:02.400 | Both groups learned a motor skill task,

01:15:05.600 | and it's very much like learning a piano.

01:15:07.520 | And you learn a sequence of movements.

01:15:09.280 | Let's just say four, one, three, two, four.

01:15:11.400 | And we have you type that out over and over again

01:15:14.040 | for periods of 30 seconds,

01:15:15.480 | and then you rest for 30 seconds,

01:15:16.720 | and then you do it again.

01:15:17.880 | You do 12 of those trials.

01:15:19.680 | And sure enough, practice seemed to get you better.

01:15:24.240 | And you were learning and your learning curve went up.

01:15:27.240 | And then we brought those participants back 12 hours later

01:15:30.800 | and we retested them on that same motor memory.

01:15:34.520 | Half of those participants spent that 12 hours awake.

01:15:37.040 | The others had a night of sleep

01:15:39.720 | in between an eight-hour night of sleep.

01:15:41.960 | When we brought the people who had learned in the morning

01:15:45.080 | and tested in the evening without sleep,

01:15:47.320 | they had retained that memory.

01:15:50.120 | They were no worse, they were just no better.

01:15:53.120 | But in the people who had slept,

01:15:55.960 | what was stunning was that they had improved

01:15:59.000 | their performance output speed by 20%

01:16:02.720 | and they'd improved their accuracy by almost 37%.

01:16:07.720 | So in other words,

01:16:10.760 | it wasn't time that you needed to produce perfection.

01:16:15.760 | It was time with sleep.

01:16:18.640 | In other words, you've often heard the statement,

01:16:21.160 | practice makes perfect, but we violated that edict.

01:16:25.160 | It wasn't practice that makes perfect.

01:16:27.600 | It's practice with a night of sleep

01:16:29.920 | that makes or leads to perfection.

01:16:33.360 | In other words, after learning,

01:16:35.320 | your brain continues to improve

01:16:37.880 | in the absence of any further practice.

01:16:40.480 | However, that learning occurs exclusively

01:16:43.800 | during periods of offline sleep

01:16:46.160 | and not across equivalent time periods while you're awake.

01:16:50.880 | Now, what was interesting in the group

01:16:52.560 | that remained awake across those 12 hours,

01:16:55.600 | we then actually brought them back

01:16:57.240 | after a further 12 hours, but now after a night of sleep

01:17:00.840 | and they showed that beautiful benefit.

01:17:04.000 | - So the sleep that can, let's say, enhance,

01:17:09.000 | although I think what we're really talking about here

01:17:11.800 | that consolidates motor learning can arrive the night after,

01:17:16.800 | meaning one finishes, let's say, learning at 11 a.m.

01:17:20.920 | and then they sleep later that night or the following night.

01:17:24.240 | And in both instances, that sleep can enhance

01:17:27.320 | or let's say consolidate the motor learning that occurred.

01:17:30.680 | - That's right.

01:17:31.520 | So it was to your question actually that we discussed earlier

01:17:33.680 | and I recall now I didn't answer it,

01:17:35.320 | which is that the things that you learn throughout the day,

01:17:39.240 | you don't have to worry about learning them

01:17:41.520 | really close to bedtime so that they're available

01:17:44.880 | and accessible for this sleep dependent work

01:17:47.360 | of sleep after learning.

01:17:49.560 | It seems to be that the human brain,

01:17:52.880 | and we've plotted this, we've looked at how,

01:17:55.400 | at what point does the brain sort of fail

01:17:58.280 | in terms of its ability to place on hold

01:18:02.600 | sort of on the runway ready to take off

01:18:04.960 | into the consolidation phase.

01:18:07.320 | And it seems to be about 16 hours

01:18:10.320 | that you can hold on to those freshly formed memories

01:18:14.200 | for about 16 hours, and then you get the chance

01:18:17.880 | to sleep and consolidate them.

01:18:19.080 | So if you learn at 11 o'clock in the morning,

01:18:21.480 | or if you learn at 7 p.m. in the evening,

01:18:23.960 | don't worry about that.

01:18:25.360 | Those memories are still going to be gathered together

01:18:28.360 | in the beautiful receptive arms of sleep

01:18:30.920 | and then knitted up and enhanced

01:18:32.840 | when it comes to procedural memories.

01:18:35.080 | And by the way, that's a key difference

01:18:36.760 | to those two types of memory.

01:18:38.920 | Sleep will take fact-based memories

01:18:41.760 | and simply save them so that you don't forget.

01:18:45.160 | It doesn't necessarily boost them anymore.

01:18:47.880 | It just simply prevents you from forgetting,

01:18:50.080 | which is what would happen otherwise across a waking day.

01:18:53.920 | - Key point.

01:18:54.960 | It's not enhancement, it's consolidation of,

01:18:59.200 | or essentially the way I might think about it

01:19:04.200 | is the new information is put into a potential memory bank.

01:19:09.360 | And that information is either flushed or maintained

01:19:12.440 | depending on whether or not you get sleep.

01:19:14.200 | - That's right.

01:19:15.040 | - There's no enhancement.

01:19:15.920 | Enhancement would be super normal levels of memory

01:19:19.480 | if you sleep.

01:19:20.360 | - And that's the case for textbook-like memory.

01:19:22.520 | In other words, sleep comes in

01:19:24.440 | and it stems the blood flow of forgetting

01:19:27.120 | from the memory wound, as it were, to get,

01:19:29.560 | I don't know why I came up with that.

01:19:30.680 | That's a terrible analogy.

01:19:31.520 | - No, I like it.

01:19:32.360 | I guess we might say hemorrhage, right?

01:19:33.680 | Like it's- - Yes.

01:19:34.560 | - Okay.

01:19:35.520 | - But so sleep comes in and prevents that from happening.

01:19:39.240 | But with motor memories, it is enhancement.

01:19:42.600 | It's that when you're awake across the day,

01:19:45.120 | you don't get any worse,

01:19:46.680 | which is what happens with fact textbook memory.

01:19:49.800 | You hold that performance,

01:19:52.280 | but then sleep comes in and it boosts you even further.

01:19:55.240 | You get a nice benefit without doing anything further.

01:19:58.880 | So then the question became to your point,

01:20:03.360 | if sleep is doing that,

01:20:04.720 | if it's not practice that makes perfect,

01:20:06.520 | but practice with sleep, what is it about sleep?

01:20:09.960 | So we looked at the sleep physiology

01:20:12.280 | and what we found were two interesting components.

01:20:15.080 | First, it seemed to be related to that lighter form

01:20:18.000 | of stage two non-REM sleep.

01:20:20.720 | I told you that textbook memory

01:20:22.600 | requires deep non-REM sleep stages three and four,

01:20:25.720 | casting back to episode one.

01:20:27.880 | Motor memory, more dependent on stage two

01:20:30.360 | and those beautiful spindles

01:20:32.720 | that are the hallmark of beginning your stage two.

01:20:36.480 | The more of those that you had,

01:20:37.840 | the greater the memory benefit the next day.

01:20:41.400 | We then wanted to say,

01:20:42.360 | well, is this effect simply something to do

01:20:45.680 | with the nighttime?

01:20:47.640 | Because that's the other hypothesis.

01:20:49.440 | It's not really about sleep.

01:20:51.240 | It's just something about nighttime-ness

01:20:53.240 | because in all of the studies I've described so far,

01:20:56.080 | they're all happening at night

01:20:57.560 | and at night they were sleeping.

01:20:59.280 | So is it really nighttime or is it specifically sleep?

01:21:03.080 | So now we did a nap study with motor skill learning.

01:21:05.480 | We repeated that and sure enough,

01:21:07.560 | even though that time period was across the day,

01:21:09.880 | not during night-ness,

01:21:12.520 | they showed this beautiful motor skill benefit

01:21:15.760 | if they napped versus if they did not.

01:21:18.240 | And then in that nap study,

01:21:20.080 | I was telling you that they were learning the sequence

01:21:22.000 | with the right non-dominant hand

01:21:24.720 | and we selected all right handers to make it equal.

01:21:28.280 | And they were typing four, one, three, two, four,

01:21:29.840 | four, one, three, two, four.

01:21:31.880 | And that right hand, as well you know,

01:21:34.360 | is controlled by the left motor cortex.

01:21:37.320 | So after in the nap study, when we recorded their sleep,

01:21:40.200 | we used very high density EEG.

01:21:42.560 | So lots and lots of sensors on top of the head.

01:21:45.160 | So we could map with high fidelity resolution,

01:21:48.240 | the surface of the brain or the surface of the scalp

01:21:51.280 | and infer what's going on in the brain.

01:21:53.800 | And what was interesting is that yes, those sleep spindles,

01:21:56.320 | the more of them that you had in the nap,

01:21:57.880 | the better your motor skill learning was,

01:22:00.200 | but there seemed to be a lateralized effect

01:22:04.240 | such that the sleep spindle activity

01:22:06.880 | on the right side of the brain,

01:22:09.040 | which controls the left hand, which was not working,

01:22:11.840 | that showed no spindle increased in activity.

01:22:14.720 | However, on the right hand activity

01:22:18.800 | that invoked activation in the left motor cortex,

01:22:22.360 | that left motor cortex and specifically the hand region

01:22:26.120 | showed a local increase in spindle activity.

01:22:30.040 | And subsequent work and work prior to ours

01:22:33.240 | had demonstrated that it's not sleep physiology globally.

01:22:38.240 | It's almost as though your sleep physiology

01:22:41.360 | responds to the mapping of the memory in the brain.

01:22:46.040 | Wherever the memory is, that's where sleep,

01:22:49.400 | when you go to sleep, sort of starts massaging the cortex

01:22:54.120 | so that you get that plasticity.

01:22:55.640 | It's almost like a good masseuse.

01:22:57.520 | You know, you sort of sit down and they say,

01:22:59.280 | where are your problem points?

01:23:00.480 | And you say, it's here and here.

01:23:03.120 | And so they don't give you a general massage.

01:23:04.880 | They go to work on the regions

01:23:06.680 | that have been working hardest,

01:23:08.480 | that require greatest attention.

01:23:10.360 | Sleep does that.

01:23:12.840 | - That's amazing.

01:23:14.600 | And reminds me of some of this work that was done,

01:23:17.320 | I think in the late '90s, early 2000s,

01:23:19.680 | Richard Morris and colleagues over in,

01:23:22.560 | I think he was in Edinburgh,

01:23:24.360 | talked about synaptic tagging.

01:23:28.720 | You know, this notion that animals or humans perform

01:23:32.600 | or learn some new motor skill,

01:23:35.000 | maybe navigation of a novel environment,

01:23:37.120 | maybe a motor skill of the 41234 that you described,

01:23:41.200 | you know, keys on a piano or something like that.

01:23:43.920 | And then it was acknowledged that the changes

01:23:47.200 | in the connections between neurons don't occur immediately,

01:23:50.000 | which meant that there had to be some sort of tag

01:23:52.160 | or label to the synapses that marked them

01:23:55.040 | for consolidation later for plasticity,

01:23:57.800 | long-term potentiation, things of that sort.

01:24:00.080 | The names don't really matter.

01:24:02.080 | I think later it became clear based on Marcus Frank's work

01:24:06.560 | and others that indeed during sleep,

01:24:09.440 | the hard rewiring of the nervous system occurs,

01:24:13.320 | plasticity occurs.

01:24:15.040 | But what you're saying is that there's a high degree

01:24:18.040 | of specificity, meaning the specific circuits

01:24:21.960 | that were active and required for the learning

01:24:24.760 | are the specific circuits that are modified,

01:24:26.520 | which on the face of it, one could say, well, of course.

01:24:28.680 | But what that means is that during sleep,

01:24:31.440 | the brain is somehow able to,

01:24:34.880 | the neurons of the brain that is,

01:24:37.280 | are able to chemically or electrically or both signal,

01:24:42.280 | like this is where there needs to be

01:24:46.400 | some modifications done.

01:24:48.000 | And then like a night crew,

01:24:49.540 | the brain self-induces its own changes,

01:24:54.160 | which is remarkable.

01:24:55.320 | - It really is.

01:24:56.160 | It's almost as though there are red flags

01:24:58.040 | that are planted in the territories

01:25:00.560 | that have undergone learning dependent plasticity.

01:25:04.480 | And they are calling out almost like hungry mouths

01:25:09.160 | that are in plasticity famine for the feast relief

01:25:13.880 | that comes by way of sleep.

01:25:16.600 | - Do we know what the factors are that are released in sleep

01:25:19.240 | that allow that to occur?

01:25:20.400 | Or is it, I'm guessing there are many.

01:25:22.600 | People love to talk about brain derived nootrophic factor,

01:25:25.600 | BDNF, which is a very interesting molecule,

01:25:28.280 | but it's probably just one of a panoply of molecules

01:25:32.360 | that are important.

01:25:34.280 | - We don't know necessarily the neurochemical processes,

01:25:37.400 | although some people have manipulated plasticity

01:25:40.000 | and then blocked it with different types of NMDA,

01:25:43.400 | which is a certain type of receptor in the brain

01:25:46.080 | for excitatory activity,

01:25:48.160 | which is the underlying basis of brain plasticity.

01:25:52.160 | So that certainly is dependent.

01:25:54.080 | But what's interesting about the sleep spindles,

01:25:56.440 | I said in the first episode that they burst

01:25:58.800 | somewhere between about 12 to 15 times per second.

01:26:01.560 | If you apply that type of stimulation

01:26:06.560 | to a particular neuronal circuit within the brain,

01:26:10.400 | that seems to be one of the, and it's not the only,

01:26:13.800 | but one of the ideal sort of sweet spot tickling of neurons

01:26:18.800 | that forces them to say,

01:26:21.320 | oh, I think I should strengthen this circuit.

01:26:24.000 | So it's almost as though these sleep spindles

01:26:26.040 | are ideally designed at the frequency,

01:26:30.240 | at the sort of tickling level of neurons

01:26:33.560 | to stimulate exactly what we think is the underlying basis

01:26:36.560 | of strengthening a memory,

01:26:38.320 | which is at the level of the neurons,

01:26:41.400 | the strengthening of synapses.

01:26:44.680 | - So interesting because we hear this fire together,

01:26:47.560 | wire together, high-frequency transmission between neurons

01:26:50.360 | is what creates plasticity,

01:26:52.200 | but this is literally a replay of previously,

01:26:55.720 | meaning earlier that day or the previous day,

01:26:57.600 | as you pointed out, activity in the given circuit

01:27:00.320 | being replayed, not unlike the work

01:27:03.280 | that you talked about earlier,

01:27:04.360 | the fast replay of neurons in the hippocampus,

01:27:07.400 | but here it's not necessarily just in the hippocampus,

01:27:09.800 | it can be in the neocortex or other structures

01:27:12.080 | that then builds up the vigor

01:27:16.800 | with which that circuit can function in the daytime,

01:27:19.020 | AKA learning, it's super interesting.

01:27:22.940 | You mentioned that this is occurring largely in stage two

01:27:26.260 | of sleep, not in rapid eye movement sleep.

01:27:28.680 | Is this business of stage two being the main period of sleep

01:27:31.820 | in which motor learning occurs unique to motor learning?

01:27:34.820 | In other words, cognitive information

01:27:36.700 | surely can get wired into the brain at night,

01:27:40.820 | but is that largely associated

01:27:42.820 | just with rapid eye movement sleep?

01:27:44.620 | What this would suggest, in other words,

01:27:46.700 | is that the earlier stages of sleep, one and two,

01:27:51.080 | and heading into three and four,

01:27:52.900 | serves a specific purpose,

01:27:54.340 | which is consolidation of motor skills

01:27:57.860 | and motor learning from the previous one or two days.

01:28:01.200 | - It does seem to be that stage two.

01:28:02.760 | Stage one is, we now think of more of a transitional stage,

01:28:07.760 | but we will speak perhaps

01:28:09.740 | when we discuss the idea of creativity,

01:28:12.380 | that it also may have a memory function,

01:28:14.620 | that very light first step of sleep.

01:28:17.500 | Stage two is certainly related to motor skill.

01:28:21.100 | In fact, stage two is fascinating.

01:28:23.180 | We used to think of it as just the stage

01:28:25.460 | that you had to go into to get to deep sleep,

01:28:28.020 | and the stage that you had to go back through

01:28:30.380 | to get up to REM sleep.

01:28:32.920 | Never made any sense to me, why?

01:28:35.220 | Because stage two non-REM sleep

01:28:37.380 | is about 40 to 50% of your night.

01:28:41.020 | Why would you spend 40 to 50% of your time asleep

01:28:45.220 | when it's just simply a gate to get to something better?

01:28:48.820 | You would spend more time

01:28:49.980 | in the something that's better stages.

01:28:53.340 | So we started to find functions,

01:28:56.300 | and stage two is distributed throughout the night,

01:28:59.140 | but those sleep spindles in stage two

01:29:02.860 | are not evenly distributed throughout the night.

01:29:06.380 | You get some of them in the first quarter,

01:29:08.380 | more of them in the second quarter of sleep.

01:29:10.780 | Certainly more in the third quarter,

01:29:12.580 | but you get a lot more of those sleep spindles

01:29:15.340 | in the last quarter of the night.

01:29:17.060 | And in fact, when we looked at the overnight study,

01:29:19.420 | where we had people learn in the evening,

01:29:21.580 | tested the next day,

01:29:22.660 | we recorded their sleep in between.

01:29:25.020 | Yes, sleep spindles predicted,

01:29:27.460 | and stage two predicted how much better

01:29:29.300 | they were the next day,

01:29:30.420 | but it was especially stage two

01:29:32.780 | in the last quarter of the night.

01:29:35.060 | Let's say I'm going to bed,

01:29:36.420 | I'm just, for argument's sake, for ease,

01:29:38.820 | midnight and I'm waking up at eight.

01:29:40.740 | It's in that sort of 6 a.m. to 8 a.m. range

01:29:44.500 | when I, if I was going to sleep at that time,

01:29:46.940 | would be getting my stage two.

01:29:48.540 | And I find that interesting

01:29:50.100 | because it is the time of night

01:29:53.380 | that we all feel it's okay to cut short,

01:29:55.700 | to get a jumpstart on the day.

01:29:57.940 | It's this modern life erosion of our sleep time.

01:30:01.580 | And what these findings would suggest

01:30:03.780 | is that you are shortchanging your brain

01:30:06.100 | of some significant motor memory performance,

01:30:09.140 | especially those classic Olympic coaches

01:30:11.700 | that have the athletes training

01:30:13.780 | until eight in the evening.

01:30:16.180 | And then they're in bed by sort of 10 or 11,

01:30:19.980 | but they have them waking up at five

01:30:22.460 | back on the athletic field at six,

01:30:25.660 | but they would gain some additional motor memory benefit

01:30:28.780 | if you just let them sleep a little bit longer.

01:30:31.540 | - I recall there was a study done at Stanford,

01:30:33.220 | relatively small study,

01:30:35.180 | but interesting nonetheless,

01:30:36.380 | because I think it was the basketball team

01:30:38.540 | that was asked to spend,

01:30:42.500 | I think an additional two hours in bed.

01:30:45.100 | - It's a sleep extension study.

01:30:46.820 | - And they were even told

01:30:48.020 | that they could do other things in bed besides sleep.

01:30:52.260 | There might've been some specifications of, you know,

01:30:54.780 | things they should not do in bed during that time,

01:30:57.660 | but at least by self-report,

01:30:58.980 | some of the students said that they slept a bit more

01:31:01.860 | or they relaxed a bit more in bed.

01:31:03.460 | And indeed, when compared to the control group,

01:31:05.820 | there was a significant improvement in their,

01:31:08.820 | I forget if it was free throw percentage, excuse me,

01:31:13.380 | or other metrics of basketball performance.

01:31:15.580 | - Yeah, it was their point scoring performance.

01:31:17.540 | It was their speed up and down the court.

01:31:19.620 | And it was a great study done by Sherry Marr

01:31:21.660 | at Stanford University.

01:31:23.700 | And she's done epic work with athletes

01:31:25.940 | to sort of replicate those findings.

01:31:28.580 | And the athlete story is interesting.

01:31:30.780 | Some people may be saying,

01:31:31.780 | well, didn't you just make a hop, skip and a jump

01:31:33.940 | from, you know, four, one, three, two, four

01:31:36.060 | to inferring complex motor skill?

01:31:38.740 | I thought about that.

01:31:39.580 | So we did a new series of studies where we,

01:31:43.180 | this is control.

01:31:44.020 | That's the nice thing about the sort of typing on a sequence.

01:31:46.740 | You can really measure that performance

01:31:48.780 | with high sort of accuracy.

01:31:50.900 | But we then switched it to a bimanual task,

01:31:53.180 | much more like learning to play a piano.

01:31:55.380 | And you were learning sequences

01:31:56.740 | that were 12, 14 items in length.

01:31:59.660 | You had to learn them over and over.

01:32:01.900 | And we had a hypothesis,

01:32:03.660 | would sleep fail at the task

01:32:07.260 | when motor skill performance became much more complex

01:32:10.540 | or would it be different?

01:32:11.780 | And what we found was that the more and more complex

01:32:13.980 | the motor skill became,

01:32:15.380 | the greater and greater the benefit of sleep

01:32:18.860 | by way of that consolidation effect.

01:32:21.340 | And then I started to hear something

01:32:23.460 | 'cause I would often be in the room

01:32:25.140 | as these participants were learning the sequence.

01:32:27.820 | And then as they were testing

01:32:30.180 | and my ears started to hear something

01:32:33.060 | that I couldn't quite believe to begin with.

01:32:36.620 | They would start to learn these motor sequences,

01:32:39.860 | but they would seem to have these pauses.

01:32:42.540 | And it's what we call chunking in motor skill memory.

01:32:45.460 | So instead of four, one, three, two, four,

01:32:47.500 | four, one, three, two, four,

01:32:48.540 | they would do four, one, three, two, four,

01:32:50.860 | four, one, three, two, four.

01:32:52.580 | And I would have them be using the same keyboard.

01:32:54.420 | And I got to know the sound of the keyboard.

01:32:56.700 | So I could hear it four, one, three, two, four,

01:32:58.660 | four, one, three, two, four.

01:33:00.060 | And then when they came back the next day,

01:33:02.660 | yes, they were performing faster,

01:33:04.100 | but they weren't just doing four, one, three, two, four,

01:33:06.140 | four, one, three, two, four.

01:33:07.900 | They were simply doing four, one, three, two, four,

01:33:09.660 | four, one, three, two, four, four.

01:33:11.020 | There was no gap at all.

01:33:13.380 | So we went into the individual responses,

01:33:16.140 | individual motor sort of finger responses.

01:33:19.140 | And sure enough, before sleep,

01:33:21.420 | there were these very clear problem points,

01:33:23.620 | almost these pain points in the motor memory sequence.

01:33:27.380 | But then when we came back after a night of sleep

01:33:29.780 | and looked at their data,

01:33:31.100 | it wasn't as though sleep simply grabbed

01:33:33.900 | the motor skill memory sort of profile

01:33:36.540 | and lifted everything up.

01:33:38.620 | Sleep was selectively going after those pain points

01:33:42.140 | and improving them.

01:33:43.900 | And that to me was interesting

01:33:45.700 | because that's the goal of a good athlete.

01:33:48.900 | It is automaticity.

01:33:51.060 | You don't want to be thinking about it.

01:33:52.900 | At some point, you go from a very conscious act

01:33:55.940 | of deliberately trying to remember

01:33:57.860 | what you should be doing

01:33:59.100 | to then not thinking about it at all.

01:34:01.940 | It's only automaticity that gives you that ability

01:34:05.420 | not to think,

01:34:06.620 | and it operates below the level of consciousness.

01:34:10.540 | - Super interesting.

01:34:11.660 | And here we're talking about specific changes in the brain

01:34:15.260 | in terms of neural activity, et cetera,

01:34:17.900 | that occur during sleep when we've been exposed to

01:34:21.380 | or engaged in a particular novel for us motor skill.

01:34:26.380 | And you see these spindles in stage two, et cetera.

01:34:30.700 | But does it work the other way as well?

01:34:32.340 | Meaning does the process of trying to learn

01:34:35.740 | a new motor skill enhance certain components of sleep

01:34:39.700 | or maybe even one's ability to sleep?

01:34:42.540 | Years ago, I heard that practicing unilateral leg movements

01:34:47.700 | practicing unilateral leg movements,

01:34:52.020 | this is perhaps a crazy idea,

01:34:53.580 | but it makes sense in the context

01:34:55.460 | of what we're talking about.

01:34:56.300 | Practicing unilateral leg movements,

01:34:57.820 | things like, you know, everyone's familiar with squats

01:35:00.140 | and deadlifts and things of that sort,

01:35:01.580 | but there are some one-legged movements.

01:35:03.180 | - Like a pistol squat.

01:35:04.140 | - I think a pistol squat does pretty hard.

01:35:06.900 | If one can do them, I'm always impressed.

01:35:09.340 | Bulgarian split squats, you know,

01:35:10.860 | foot up on the bench and then squatting down

01:35:12.500 | with a dumbbell, things like that.

01:35:14.140 | Or just unilateral movements that require a lot

01:35:17.540 | of mental attention to the performance of that movement.

01:35:21.220 | Could be in the gym, but it could be something else as well.

01:35:23.480 | Could make you think about a dancer trying to learn

01:35:25.420 | how to organize their steps,

01:35:28.860 | where they have to pay careful attention

01:35:30.260 | to right versus left foot, right?

01:35:31.580 | They always say, you know, like people have two right feet,

01:35:33.700 | they can't, you can't dance up,

01:35:35.020 | two right feet or two left feet.

01:35:35.860 | - By the way, for those listening,

01:35:36.820 | Andrew's looking at me right now

01:35:37.980 | when he's saying two right feet, rightfully so.

01:35:40.700 | - No, I have no knowledge of your dancing ability

01:35:43.940 | or challenges. - Absence thereof.

01:35:45.980 | - As I recall, there may have been some very preliminary data

01:35:52.140 | about changes in the amount of certain sleep stages,

01:35:55.940 | according to whether or not someone had tried

01:35:58.180 | to learn a skill, in this case,

01:35:59.820 | unilateral limb performance the previous day.

01:36:04.820 | So in other words, if one wants to improve their sleep,

01:36:08.380 | would the attempt to learn a new motor skill

01:36:11.660 | be one avenue to improve one's sleep?

01:36:14.820 | - It's interesting.

01:36:15.980 | If you look at some of the data,

01:36:17.340 | it's a little bit mixed in terms of motor skill learning,

01:36:20.620 | but there are some studies demonstrating

01:36:23.340 | that it's true for textbook-like memory.

01:36:26.100 | And there's a study, gosh, done many years ago,

01:36:28.220 | again, by the great German group of Jan Born,

01:36:31.700 | and they simply asked the question,

01:36:34.340 | if you were to just not be learning very deliberately

01:36:39.260 | and intensively through a textbook-like set of information,

01:36:43.940 | and then we just measure your sleep to get a baseline,

01:36:46.580 | and then we force you to have a very long,

01:36:50.020 | very intensive learning session of these facts,

01:36:53.660 | and then we measure your sleep again,

01:36:55.620 | is there any difference relative

01:36:57.780 | to the non-intensive learning day

01:37:00.140 | versus the intensive learning day?

01:37:02.060 | And indeed, what they found was that there was an increase

01:37:04.940 | in their deep non-REM sleep, in their deep slow-wave sleep.

01:37:08.940 | And again, we think it's almost,

01:37:11.260 | we describe it as a homeostatic response,

01:37:14.420 | which is just a fancy way of saying

01:37:16.180 | that when the brain is driven to undergo a demand,

01:37:20.980 | then sleep will respond to try to accommodate that demand.

01:37:25.900 | And so I would say that there are probably

01:37:28.980 | many other things, and we discussed this in episode two

01:37:31.540 | in terms of, A, how to optimize your sleep,

01:37:34.020 | that probably carry a bigger bang for your buck

01:37:37.300 | in terms of optimizing and enhancing your sleep,

01:37:40.900 | but is there any evidence to suggest that that's the case?

01:37:44.580 | There does seem to be some evidence in the literature, yes.

01:37:47.780 | - So interesting, I certainly know the experience

01:37:51.780 | of trying to learn a lot of information

01:37:54.060 | and then feeling like my sleep is that much deeper,

01:37:56.500 | although I've also experienced the challenges

01:37:58.900 | in, quote-unquote, turning my brain off

01:38:01.300 | when I've been trying to learn something

01:38:02.700 | and then it's late in the evening,

01:38:03.980 | forget the caffeine component,

01:38:05.620 | but just the information is spooling in my head,

01:38:08.940 | maybe some pre-test anxiety, that kind of thing.

01:38:13.460 | So I think that the tools and protocols

01:38:15.460 | that you offered so generously in episodes one, two,

01:38:19.100 | and three are especially important under those conditions,

01:38:22.100 | learning how to really taper off one's level

01:38:25.180 | of thinking and planning and arousal in the evening,

01:38:28.140 | really bring things down so that one can access that sleep.

01:38:31.380 | I mean, one only wishes that the more we did during the day,

01:38:34.380 | the easier it would be to sleep.

01:38:36.100 | And I think to some extent that's true,

01:38:37.860 | but there's some conditions in which doing more,

01:38:42.060 | thinking about more,

01:38:43.700 | and I guess that's sort of the irony, right?

01:38:46.360 | I interrupted myself, but on purpose,

01:38:47.860 | that wouldn't it be wonderful if the amount and ease

01:38:51.380 | of sleep was directly proportional

01:38:53.660 | to how much we needed to sleep?

01:38:55.620 | That's one of the tricks in this whole business.

01:38:58.380 | - Fickle system sometimes.

01:38:59.580 | - Right, like sometimes when we really need sleep,

01:39:02.500 | we're dealing with something psychologically challenging,

01:39:04.620 | or we need to learn something, we have an exam,

01:39:07.680 | that often can be when it's most difficult to sleep.

01:39:09.860 | - Gets right in the way of what we need most.

01:39:12.660 | Although coming back to your point,

01:39:14.100 | I think physical activity does seem to be

01:39:17.660 | one of those things that is very good.

01:39:19.620 | And I'm remiss to have not included it

01:39:23.460 | in the optimization or the unconventional tips.

01:39:26.740 | There is a very good robust literature now

01:39:29.220 | demonstrating that if you are physically active

01:39:32.140 | during the day, you can boost the quality of your sleep,

01:39:35.500 | particularly your deep sleep at night.

01:39:38.520 | It seems to be, there are some subtle differences

01:39:42.060 | in terms of whether you're doing aerobic versus anaerobic,

01:39:45.260 | so let's say versus, you know,

01:39:47.020 | doing a spin bike class for an hour

01:39:49.060 | versus lifting resistance,

01:39:51.020 | or doing resistance training for an hour

01:39:53.220 | or strength training.

01:39:54.500 | There's subtle differences,

01:39:55.780 | but net that overall the big picture view

01:39:58.820 | is that when you perform exercise,

01:40:01.000 | you drive a response from enhanced sleep,

01:40:04.020 | particularly deep sleep at night.

01:40:05.540 | And I think many people have had that experience.

01:40:07.380 | You've been out on a long hike,

01:40:09.060 | maybe a 10, 12 mile hike,

01:40:10.980 | or you've just been working in the garden,

01:40:13.780 | doing really, you know,

01:40:15.140 | sort of long landscaping work throughout the day,

01:40:18.140 | six or seven hours.

01:40:19.700 | And you just come in and you go to bed that night

01:40:23.060 | and you just know that this is going to be

01:40:26.300 | the most Royal night of sleep that you could.

01:40:29.320 | You know it ahead of time,

01:40:31.120 | you know, sort of ear hole to elbow.

01:40:34.380 | And that evidence is now very clear.

01:40:38.400 | The one interesting thing,

01:40:39.680 | if you dig into that data though,

01:40:41.760 | you can drive increases in deep sleep by way of exercise.

01:40:45.520 | It does seem to come at a little bit of cost to REM sleep.

01:40:49.640 | Exercise may throttle back some of your REM sleep.

01:40:53.400 | Now don't fear that.

01:40:55.040 | It may just simply be that every night,

01:40:57.320 | and we know this,

01:40:58.740 | my sleep and my stages of sleep

01:41:01.460 | are going to be much different to yours

01:41:03.980 | in how they are structured and how they play out.

01:41:06.800 | But even within me, the same individual, Matt,

01:41:10.300 | my sleep stages vary from one night to the next to the next.

01:41:14.300 | Some of that is idiosyncratic.

01:41:16.180 | Others are, or other reasons depend on

01:41:19.180 | what I've been doing during the day.

01:41:21.620 | And so it may be that we don't need to get concerned

01:41:23.960 | about that modest reduction in REM

01:41:26.060 | due to exercise enhanced non-REM,

01:41:28.880 | because it's simply that when you've gone through

01:41:30.960 | that form of activity as a human being during the day,

01:41:34.880 | what you need is that type of sleep

01:41:37.080 | more so than perhaps REM sleep.

01:41:39.840 | And therefore the next night, things calibrate back down.

01:41:43.320 | Let's say I wasn't as active.

01:41:44.560 | I just sort of went to work and I'm back to baseline again.

01:41:47.740 | So I don't get too concerned about that,

01:41:50.440 | but I just want to bring it up.

01:41:51.600 | It's there in the literature.

01:41:52.920 | - Yeah, I think it's a very interesting point.

01:41:54.920 | And one just has to trust that nature knows best

01:41:58.260 | in modifying the percentage of different sleep stages

01:42:02.100 | according to our daytime activity.

01:42:04.140 | Again, highlighting the key relationship,

01:42:07.900 | I mean, the closely tethered relationship

01:42:10.340 | between daytime activity and sleep and vice versa.

01:42:13.540 | - Correct.

01:42:14.380 | Yeah, and it's a reciprocal loop

01:42:17.260 | because what we found is that exercise during the day

01:42:19.900 | can enhance sleep at night,

01:42:21.460 | but also what we found is that sleep at night

01:42:24.300 | enhances your athletic performance the following day.

01:42:27.180 | And I'm not just talking about motor skill,

01:42:29.020 | memory upstairs in the brain.

01:42:30.580 | I'm talking about physical activity in the body.

01:42:33.100 | And if you limit sleep to let's say less than six hours,

01:42:36.500 | the data demonstrates that your peak muscle performance

01:42:39.720 | is decreased.

01:42:40.820 | Your peak vertical jump height decreases.

01:42:43.900 | Your time to exhaustion decreases.

01:42:46.580 | In some cities, it was up to 30%.

01:42:49.020 | So if you're training for a 10K marathon,

01:42:51.060 | but you don't get enough sleep the night before,

01:42:52.780 | you're done by seven.

01:42:54.900 | We also know that it decreases

01:42:56.660 | perhaps more than almost any of those.

01:42:59.420 | And it's striking the brain's motivation to exercise at all.

01:43:04.420 | So in fact, many people may be able to get close

01:43:09.340 | to their peak muscle strength when they are underslept.

01:43:12.660 | Chances are they're probably never going to get

01:43:14.540 | to the chance to express that

01:43:16.300 | because their motivation to exercise just drops off.

01:43:18.980 | And I think many people will resonate

01:43:20.580 | that you had a bad night of sleep.

01:43:22.060 | I just don't want to go to the gym the next day.

01:43:24.500 | The final part of that is injury risk.

01:43:26.660 | There is a significantly elevated injury risk.

01:43:28.940 | And if you ask most athletes,

01:43:31.420 | okay, what am I particularly concerned about?

01:43:34.020 | Is it my performance?

01:43:35.620 | Or if I had some kind of injury,

01:43:37.620 | that knocks me out for the rest of the season.

01:43:39.980 | And so I've had the fortunate chance to work

01:43:42.420 | with many professional teams of different kinds.

01:43:45.860 | And gradually they are realizing what I sort of long said,

01:43:49.380 | and it's a crass statement,

01:43:50.500 | but I think sleep is probably the greatest

01:43:53.180 | legal performance enhancing drug

01:43:55.100 | that most athletes are not abusing enough.

01:43:58.180 | - I could not agree more.

01:43:59.660 | I mean, I feel like every time I say sleep

01:44:01.900 | is the bedrock of mental health,

01:44:03.220 | physical health and performance,

01:44:04.820 | it's sometimes perceived as just kind of like,

01:44:09.780 | oh yeah, sleep, we need to sleep.

01:44:12.060 | But there's no question that the positive effects

01:44:16.020 | of getting excellent sleep on a consistent basis,

01:44:19.860 | far out way and perform any kind of supplement

01:44:23.980 | or even performance enhancing drug.

01:44:25.620 | In fact, most supplements and performance enhancing drugs

01:44:28.740 | that can indeed improve performance of various kinds

01:44:32.900 | seem to only function or function best,

01:44:35.460 | certainly on a backdrop of excellent sleep.

01:44:38.420 | And I should say that I think you've done a brilliant job

01:44:41.780 | of being very explicit about the fact

01:44:44.660 | that you need to get all of the basics in place.

01:44:48.460 | And then it's great to think about fine tweaking

01:44:50.820 | with optimization of things like supplementation

01:44:53.540 | and all these other things.

01:44:55.300 | And I think sometimes that message has been

01:44:57.380 | maybe a little bit more mixed in the social media environment

01:45:01.500 | that we often don't think about the basics

01:45:04.940 | and we go straight to supplementation where you would say,

01:45:07.700 | gosh, there's actually a log order of magnitude benefit

01:45:11.180 | that's on the table.

01:45:12.500 | If only you had to do some of the basic things

01:45:14.500 | that your grandmother would probably tell you.

01:45:17.580 | Eat right, get your stress sorted out,

01:45:20.540 | do some physical activity

01:45:21.740 | and make sure that you get some sleep.

01:45:23.100 | Do those things and you're very far along.

01:45:25.380 | Now there's more opportunity on the table

01:45:27.260 | for fine tuning as you've elegantly discussed.

01:45:30.100 | But I think I just want to acknowledge

01:45:31.580 | that I think you've done a really great job

01:45:34.060 | of being balanced in that message.

01:45:36.420 | And I hope people in the general sphere

01:45:39.820 | can appreciate how hard that is to do.

01:45:42.580 | It's not an easy thing

01:45:43.860 | when you are talking about supplementation

01:45:45.500 | because at first it sounds as though, gosh,

01:45:47.820 | all of the speak and you describe great data

01:45:50.380 | means that it is the holy grail of enhanced human beings.

01:45:55.380 | But you're always careful to say this after the foundation.

01:45:59.100 | And I can give a very good example with sleep.

01:46:01.860 | Let's say that you're trying to manage your weight

01:46:03.940 | and lose weight and you're dieting,

01:46:06.900 | but you're not getting sufficient sleep.

01:46:09.020 | What we've discovered is that yes,

01:46:11.180 | you will lose weight when you're dieting,

01:46:14.820 | even though you're not getting enough sleep.

01:46:16.500 | The problem is that almost 60% of the weight that you lose

01:46:20.820 | will come from lean muscle mass and not fat.

01:46:25.460 | In other words, when you are underslept and dieting,

01:46:28.620 | you keep what you're trying to lose, which is the fat,

01:46:31.740 | and you lose what you wish to keep, which is the muscle.

01:46:35.380 | So your body does something very interesting

01:46:38.140 | in its removal of different types of energy stores

01:46:43.740 | in your body when you are not slept.

01:46:46.580 | It becomes very stingy with fat

01:46:48.780 | and it will not give it up when you are sleep deprived,

01:46:52.580 | which is very interesting.

01:46:53.420 | Why would that be, by the way?

01:46:55.460 | - Muscle is such a metabolically demanding tissue.

01:46:58.100 | By not sleeping well, you're sending signals

01:47:00.980 | that there really isn't the capacity to take care

01:47:02.860 | of what you already have,

01:47:03.860 | much less increase the size of the engine.

01:47:07.020 | - That's exactly right.

01:47:07.940 | And then think about fat, which is in terms of its energy,

01:47:12.300 | unit benefit, it has at least perhaps twice

01:47:16.780 | the caloric value that protein does.

01:47:19.500 | So if you are underslept, that is a warning sign

01:47:22.220 | to any evolutionary species past that things are dire.

01:47:26.880 | So whatever I'm going to do, this is break glass

01:47:29.940 | in case of emergency situation.

01:47:32.300 | And if you're not getting enough calories,

01:47:34.740 | I'm gonna hold onto the thing

01:47:36.140 | that has the highest caloric value right until the end,

01:47:40.240 | which is fat, and I'm going to give away the stuff

01:47:43.340 | that doesn't have as much caloric benefit

01:47:45.780 | because I am in a caloric deficit right now.

01:47:48.900 | Now, of course, that's strange

01:47:49.940 | because the person trying to lose weight

01:47:51.700 | perhaps is rightfully trying to lose weight

01:47:54.400 | based on them being somewhat overweight.

01:47:57.180 | But that's the biology that we think explains

01:48:00.040 | why that that's the case.

01:48:01.280 | It's not just a strange phenomenon.

01:48:03.140 | It's a very logical one.

01:48:04.860 | - Yeah, it is a logical one.

01:48:06.060 | And thanks for the support around, you know,

01:48:10.480 | my constant voicing and revoicing

01:48:14.480 | of the pillars of health that you mentioned,

01:48:16.920 | you know, exercise, sleep.

01:48:17.920 | Well, I put it in the order of sleep

01:48:20.080 | as the most important pillar.

01:48:22.340 | And then one could argue about the order of the others,

01:48:25.560 | but in no specific order, light, which dovetails with sleep,

01:48:30.200 | but nutrition, movement, exercise, social connection,

01:48:35.480 | stress modulation, these kinds of things.

01:48:37.540 | - Yeah, the fact that the speed with which

01:48:39.660 | that comes out of your mouth tells you

01:48:41.300 | how many times you've said it

01:48:44.060 | and you've said it over and over.

01:48:45.340 | It's wonderful.

01:48:46.300 | - Well, thank you.

01:48:47.120 | It's interesting because they are the basics,

01:48:49.100 | but they are basics that need to be re-upped every 24 hours.

01:48:52.740 | And so often I feel like we all need

01:48:55.060 | to be reminded every 24 hours.

01:48:57.220 | I also, you know, one of the most common questions I get

01:49:00.020 | is what should I take?

01:49:01.480 | People are like, if I had a dollar

01:49:02.780 | for every time somebody said, what should I take?

01:49:04.460 | You know, I'd keep podcasting, but I'd be a gazillionaire.

01:49:08.820 | But my response is always the same,

01:49:10.300 | which is how's your sleep?

01:49:11.980 | The first question I say is how's your sleep?

01:49:13.400 | And then they think I'm going to suggest a sleep supplement,

01:49:15.300 | but I want to know whether or not people are sleeping well

01:49:17.680 | on a consistent basis.

01:49:18.620 | And that opens up a whole set of discussions.

01:49:21.400 | And then inevitably we forget

01:49:23.540 | about what one should take conversation.

01:49:25.960 | I think it's the rare individual who's sleeping very well

01:49:29.540 | every night of their life.

01:49:30.400 | There are such individuals.

01:49:31.540 | And then the what should I take conversation makes sense.

01:49:34.400 | In a certain context.

01:49:35.700 | There's something I wanted to just return to for a moment

01:49:38.580 | before I move on to the next topic,

01:49:41.380 | which is you mentioned all the significant deficits

01:49:45.860 | that occur in motor performance

01:49:47.860 | when one has not slept that well the night before.

01:49:50.140 | Grip, strength, vertical jump, motivation, et cetera.

01:49:54.020 | You know, we're not here to deliver anything

01:49:59.540 | except the facts to people.

01:50:01.900 | And we're certainly not here to soften the blow of reality.

01:50:05.440 | But there are a good number of people

01:50:07.320 | that will have say a physical performance, like a race,

01:50:09.880 | they're training for a half marathon,

01:50:11.560 | or they have a big game the next day,

01:50:14.760 | or they have some performance event the next day.

01:50:18.100 | And by virtue of butterflies, anxiety, travel,

01:50:22.800 | an alarm going off in a hotel in the middle of the night,

01:50:25.240 | I've had that experience, et cetera,

01:50:26.980 | that they may not get the best night's sleep

01:50:29.520 | the night before.

01:50:31.500 | And obviously there are going to be ramifications of that.

01:50:34.660 | But I'm reminded of a study that was done

01:50:38.960 | by Ali Crum's lab at Stanford,

01:50:42.060 | where people wear sleep trackers.

01:50:45.760 | And they actually knew how much

01:50:50.580 | and how well or poorly they slept the night before.

01:50:53.900 | I don't know how detailed the analysis was,

01:50:55.380 | but it was Stanford Sleep Center,

01:50:56.500 | so presumably it was reasonably detailed.

01:50:58.980 | And then the next day, with that knowledge in hand,

01:51:02.860 | either lied to the people or told them the truth

01:51:07.580 | about how well they had slept the night before or poorly.

01:51:10.000 | For instance, if someone had got eight hours

01:51:11.740 | of great sleep the night before,

01:51:13.360 | they might've told them,

01:51:14.560 | "Hey, you got eight hours of great sleep the night before."

01:51:16.460 | Or they might've been in a condition where they said,

01:51:18.420 | "Hey, you know what?

01:51:19.260 | Your sleep last night wasn't that great."

01:51:21.820 | Or if somebody got five hours of sleep,

01:51:24.040 | they might've said, "Hey, you know,

01:51:25.460 | you got eight hours of great sleep."

01:51:26.820 | So there was a lot of lying involved in this study.

01:51:29.620 | But basically what they observed is that performance in,

01:51:33.780 | I think it was motor skill performance,

01:51:35.700 | but it might've been cognitive,

01:51:36.700 | but that's not the issue here.

01:51:39.040 | The point is that much of our performance can be dependent

01:51:42.820 | on our subjective understanding

01:51:45.400 | of how well or poorly we slept the night before.

01:51:49.380 | In other words, there can be belief effects.

01:51:51.620 | - That's right.

01:51:52.460 | - So this is one of the concerns

01:51:53.740 | about placing too much emphasis

01:51:57.140 | on the one poor night's sleep.

01:52:00.280 | You know, and obviously people should be mindful of injury,

01:52:02.620 | as you pointed out,

01:52:03.460 | but if someone has a big race or a big event the next day

01:52:06.620 | and they just don't sleep well,

01:52:08.340 | we have to be careful that the mere knowledge

01:52:12.040 | that they're not going to perform as well,

01:52:14.220 | because that's what the data say,

01:52:15.820 | can potentially be offset by the Ali Crum study,

01:52:21.780 | which is if they believe like,

01:52:22.900 | "Hey, a lot of it is about what they believe

01:52:24.780 | "about their own sleep to be,"

01:52:26.060 | which just tells you that performance can,

01:52:29.500 | and motivation presumably,

01:52:31.260 | can override some of the physiology.

01:52:33.620 | There's, you know, and again,

01:52:35.060 | you can't rescue what you can't rescue.

01:52:37.820 | - No, and I think it's a very good point

01:52:39.460 | because it comes back to our discussion

01:52:40.900 | about the placebo effect in some ways,

01:52:42.700 | which is this is mind over matter

01:52:45.180 | and that your biological state.

01:52:46.940 | So one of the things I do

01:52:48.340 | when I'm working with professional athletes

01:52:50.740 | and we're doing sleep tracking,

01:52:52.260 | often I'm working with a coach

01:52:54.780 | and I will say during that period

01:52:56.420 | where they're on the road

01:52:59.820 | and now they've got seven games to play in the playoffs,

01:53:03.620 | let's keep tracking their sleep

01:53:05.140 | and let's you and I make sure

01:53:06.700 | that we're trying to optimize this athlete,

01:53:09.340 | because they've given consent,

01:53:10.820 | they want to have their sleep as good as possible

01:53:13.220 | and they want us to help them do that.

01:53:15.420 | But I say at that point,

01:53:16.940 | we will simply look at the data night after night

01:53:19.940 | and then we can describe the data

01:53:21.740 | that they've been having at the end of the week

01:53:23.900 | after they finished the series.

01:53:26.380 | Because for exactly that reason,

01:53:28.420 | if you start giving them feedback,

01:53:29.820 | we don't want to erode confidence.

01:53:32.100 | And with sleep trackers,

01:53:33.300 | there is such a thing called orthosomnia

01:53:36.540 | and it's now a described situation.

01:53:39.780 | Orthosomnia in medicine words mean something.

01:53:45.020 | So ortho people will be familiar with in medicine,

01:53:49.100 | orthopedics, orthodontics,

01:53:51.100 | it's about getting things straight.

01:53:53.140 | Orthopedics, getting your sort of bone straight,

01:53:56.140 | orthodontics, getting your teeth straight.

01:53:58.180 | Orthosomnia is about trying to get your sleep straight

01:54:01.940 | and being so worried about that,

01:54:03.620 | that it compromises your sleep.

01:54:05.740 | Now we don't know exactly what proportion of people,

01:54:08.340 | it may be less than 10% who use sleep trackers,

01:54:11.460 | but I would say that to anyone listening,

01:54:13.860 | if you are tracking your sleep with a tracker

01:54:17.380 | and you're experiencing the sleep related anxiety,

01:54:19.980 | do one of two things.

01:54:21.300 | First, take my recommendation,

01:54:22.820 | which is that only on let's say a Sunday afternoon,

01:54:26.220 | do you open up the app and check your data.

01:54:28.580 | So that way you can still be measuring your sleep,

01:54:30.420 | which is very helpful,

01:54:32.180 | but you don't have to get the anxiety morning after morning.

01:54:35.540 | The other is that if you are truly starting

01:54:37.940 | to get a very negative experience,

01:54:40.060 | take it off, put it in the drawer

01:54:42.220 | and just get your sleep confidence back

01:54:44.940 | using some of the suggestions that we had

01:54:47.300 | in the optimization episode.

01:54:48.980 | And only then return to using that tracker.

01:54:52.420 | What's also interesting,

01:54:53.740 | it relates to what you were saying

01:54:55.260 | about beliefs and intention.

01:54:57.940 | They did another great study

01:54:59.820 | where they looked at this cortisol rise in the morning

01:55:01.980 | that you and I have discussed on this series many times,

01:55:04.620 | which starts to happen sort of just before you're waking up

01:55:07.700 | and really rises into the morning.

01:55:09.660 | What they did was they brought participants

01:55:13.220 | into the laboratory and they had them go to sleep

01:55:16.100 | at around 11 o'clock at night.

01:55:18.940 | And then in one group, they said,

01:55:20.180 | we're going to wake you up at 7 a.m. in the morning.

01:55:23.140 | The other group, they said,

01:55:23.980 | we're going to wake you up at 5 a.m. in the morning.

01:55:27.420 | Well, it turns out that both of those groups

01:55:30.460 | were woken up at 7 a.m.

01:55:33.220 | But what was bizarre is that in the group

01:55:35.740 | that was told they were going to wake up at 5 a.m.,

01:55:40.140 | their cortisol release started to rise around 5 a.m.

01:55:45.940 | In other words, just the knowledge before sleep

01:55:49.460 | that you're going to be woken up at 5 a.m.

01:55:52.460 | changed the non-conscious brain's release

01:55:56.140 | of a stock standard prototypical hormonal release mechanism.

01:56:01.100 | And that comes right back to this idea

01:56:02.940 | that we were speaking about with time,

01:56:05.660 | that consciously we have lost time perception

01:56:09.020 | when we're sleeping, but non-consciously,

01:56:11.140 | it seems as though the brain is still knowing

01:56:13.820 | what's going on because for that early morning flight,

01:56:16.300 | you wake up two minutes before your alarm.

01:56:18.660 | Well, perhaps the reason why is that you've learned

01:56:22.380 | that you have to wake up at that time

01:56:24.260 | and you've changed your cortisol response,

01:56:26.820 | which would normally, because you don't wake up

01:56:28.940 | for an early morning flight every day,

01:56:31.020 | would normally not come for two hours,

01:56:33.020 | but it's arriving earlier.

01:56:35.020 | It just blew me away.

01:56:36.380 | I couldn't believe that the brain non-consciously

01:56:39.500 | could change a hormonal profile

01:56:41.580 | simply based on me telling you

01:56:43.500 | what time you're going to wake up the next morning.

01:56:45.980 | - Spectacular.

01:56:46.940 | And really, as you pointed out,

01:56:48.740 | really speaks to the fact that during sleep,

01:56:51.380 | there is a lot of processing going on,

01:56:53.460 | subconscious, unconscious, cognitive processing.

01:56:57.540 | And we know this in the form of dreams,

01:56:59.820 | a topic that we'll talk about

01:57:01.540 | in a subsequent episode of this series.

01:57:03.700 | But okay, so you've shared with us the clear value

01:57:07.060 | of getting the best possible night's sleep

01:57:09.140 | before what I call a bout of learning.

01:57:11.500 | - Yeah.

01:57:12.900 | - You also shared with us the clear value

01:57:15.300 | of getting sleep after being exposed

01:57:17.980 | to some new information, aka a bout of learning.

01:57:22.980 | And you've explained to us the key relationship

01:57:25.780 | between sleep and motor learning,

01:57:28.980 | learning of new motor skills.

01:57:31.060 | What are some other aspects of brain and cognition

01:57:35.020 | for which sleep exerts a significant positive effect?

01:57:40.020 | - So those for a while were the first two things

01:57:43.860 | that we really thought sleep was doing

01:57:45.100 | for learning and memory.

01:57:46.660 | Sleep before learning to make those memories,

01:57:48.860 | sleep after learning to consolidate them

01:57:52.060 | and hit the save button.

01:57:53.900 | But then data started to emerge

01:57:56.620 | and we started to look at this too,

01:57:58.860 | that sleep was much more intelligent

01:58:01.340 | than we ever imagined

01:58:02.500 | when it comes to information processing.

01:58:04.740 | Sleep doesn't simply just strengthen individual memories

01:58:08.580 | like isolate islands and connected.

01:58:12.020 | Sleep after learning

01:58:14.340 | is almost a form of informational alchemy

01:58:17.740 | that sleep will take these new memories

01:58:20.420 | and it will start to interconnect them

01:58:22.500 | and cross-link them with the new information

01:58:26.220 | that you've learned,

01:58:27.060 | because usually information that you're learning

01:58:28.660 | during the day is interconnected

01:58:30.820 | and sleep was building those connections

01:58:32.500 | between new memories,

01:58:34.140 | but also it was integrating them

01:58:36.980 | into the back catalog

01:58:38.500 | of all of your past autobiographical memory systems

01:58:42.660 | so that you woke up the next day

01:58:44.860 | and you had a revised mind wide web of associations.

01:58:49.860 | And a good example of this,

01:58:51.940 | we did a study, gosh, very early on

01:58:55.140 | where we asked the question,

01:58:56.460 | which stage of sleep then is important

01:58:58.700 | for this type of,

01:59:00.900 | I almost think of it as a strange analogy,

01:59:04.140 | but almost like group therapy for memories

01:59:07.300 | that at the end of the day,

01:59:09.220 | every new memory gets a name badge

01:59:12.340 | and sleep gathers in all of these memories

01:59:15.300 | into the same room.

01:59:16.660 | And it forces you, however,

01:59:18.740 | to speak to the people,

01:59:19.660 | not at the front of the room

01:59:20.740 | that you think you've got the most obvious connection with,

01:59:23.140 | it forces you to speak to the people

01:59:24.500 | all the way at the back of the room

01:59:25.620 | that you don't think you've got really

01:59:26.820 | any connection with at all,

01:59:28.380 | but it turns out that you do

01:59:31.020 | because sleep doesn't simply build associations

01:59:34.180 | and connections, it does.

01:59:35.740 | It seems to bias the brain

01:59:37.100 | towards building the most non-obvious distant associations.

01:59:41.020 | It's almost like a Google search gone wrong

01:59:46.100 | that during the waking day,

01:59:48.940 | our memories, which are still,

01:59:50.540 | our brains are still associative

01:59:51.940 | in how they can build links and connections.

01:59:54.820 | That's like page one of the Google search.

01:59:57.220 | So let's say that I type in, you know, Andrew Huberman

02:00:00.660 | and the first page I get,

02:00:02.140 | the first hit is the Huberman Lab website, great.

02:00:05.180 | But if I go to page 20,

02:00:08.140 | it's about a field hockey game in Utah.

02:00:11.100 | And I think, heck in a second, what's Andrew doing?

02:00:13.620 | - You didn't know?

02:00:14.460 | - But yeah, I know exactly.

02:00:15.620 | - I don't think I've ever played field hockey.

02:00:16.980 | I've been to Utah, it's a beautiful state.

02:00:18.820 | - Oh, it's beautiful.

02:00:20.220 | But if I look, I can actually see that

02:00:22.540 | there is a very distant non-obvious association.

02:00:25.140 | I can understand why it's there.

02:00:26.980 | That's what sleep seems to be over indexing for

02:00:31.540 | in this associational framework.

02:00:33.340 | So then we asked, well, what is it about sleep?

02:00:35.660 | So we had participants perform anagram solving tasks.

02:00:40.580 | And anagrams are simply these words that are,

02:00:43.180 | the letters are all jumbled up

02:00:44.540 | and you have to kind of stare at them or work through them.

02:00:47.140 | And all of a sudden you start to see which word it really is

02:00:51.260 | because at first it's all jumbled up and it makes no sense.

02:00:54.700 | But we didn't teach them it before sleep and after sleep.

02:00:57.900 | We did something different.

02:00:59.340 | We woke them up out of different stages of sleep.

02:01:02.100 | Why?

02:01:03.100 | Well, when you come out of different stages of sleep,

02:01:07.140 | there is still some degree of the biology

02:01:09.980 | of that sleep state that lingers in your brain,

02:01:13.820 | almost like vapors coming off the stage of sleep

02:01:16.380 | that you've just exited.

02:01:17.980 | And it only lasts for about two minutes or so.

02:01:20.980 | But what was nice is that this anagram test

02:01:23.420 | you could do within two minutes.

02:01:25.540 | So we would wake them up out of different stages of sleep

02:01:28.580 | and then we'd have them quickly do these anagrams.

02:01:32.220 | And I told you that for fact-based memory,

02:01:35.540 | that sleep after learning was important

02:01:37.460 | to strengthen the individual memories.

02:01:40.020 | And it was particularly non-rapid eye movement sleep

02:01:42.740 | that was doing that strengthening of the individual facts.

02:01:46.180 | Now what we found is that the association creativity benefit

02:01:50.620 | of sleep was very different.

02:01:52.740 | That cross-linking benefit came by way,

02:01:55.060 | it seemed, of REM sleep.

02:01:56.540 | Because when we woke them up out of REM sleep

02:01:58.500 | compared to non-REM sleep,

02:01:59.980 | they were 30% more capable of solving these anagrams.

02:02:04.820 | And when we looked at how they were solving them,

02:02:07.300 | it was interesting.

02:02:08.460 | Coming out of non-REM sleep,

02:02:09.740 | it was very sort of analogical.

02:02:12.540 | It was very, what we think of as very sort of convergent,

02:02:17.140 | very focused way of trying to logically solve the problem.

02:02:22.140 | But with REM sleep,

02:02:23.380 | it was much more divergent fluid intelligence.

02:02:26.580 | It was almost as if they were just standing back

02:02:28.900 | and waiting for it, and then, bop,

02:02:30.580 | it just popped out in front of them.

02:02:32.060 | All the letters kind of reorganized and clicked into place.

02:02:36.100 | And then there was a subsequent study

02:02:39.260 | that did something different.

02:02:41.060 | It looked specifically at creative insight.

02:02:45.540 | And it was a lovely study,

02:02:47.740 | and they performed something called

02:02:48.860 | the numeric number reduction test,

02:02:50.740 | which is one of those tests

02:02:52.020 | that psychologists love to administer

02:02:53.820 | and participants hate to perform.

02:02:56.340 | And here's what happens.

02:02:57.580 | You're shown a whole string of numbers,

02:02:59.860 | and you are given a certain set of rules,

02:03:02.500 | and you have to work through those number problems

02:03:04.660 | and come out with a final end answer.

02:03:07.100 | And you're told that you're going to be judged simply

02:03:09.300 | on how many correct final end answers that you get.

02:03:12.940 | And you work through hundreds of these problems.

02:03:15.580 | What they don't tell you in the instructions, however,

02:03:19.740 | is that there is a hidden rule here

02:03:22.380 | embedded in that all of those sequences,

02:03:25.140 | all of the sequences are different that you have to solve,

02:03:27.140 | but there is one common rule that binds them all together,

02:03:30.940 | which is that the second part,

02:03:33.100 | sort of the second component of the solution,

02:03:35.380 | so you're working through,

02:03:36.500 | let's say it's a 10-digit string number,

02:03:38.580 | and you have to apply these rules to the first number,

02:03:40.740 | then carry it through to the second number,

02:03:42.140 | and then to the third number.

02:03:44.060 | The second partial number that you produce

02:03:46.620 | in this string of calculations

02:03:48.780 | to get to the final end answer,

02:03:51.140 | it turns out to be always the same end answer.

02:03:55.060 | So in other words, if you clue on to this hidden rule,

02:03:58.420 | all you have to do is work up to the first,

02:04:00.780 | let's say 10% of every problem.

02:04:02.540 | You can just shortcut the rest of it,

02:04:04.220 | and you just write down the number,

02:04:05.460 | 'cause you are told that the only thing

02:04:08.260 | we're going to judge you on is the end answer.

02:04:10.340 | So they trained participants

02:04:11.860 | on these sort of numeric number reduction trials,

02:04:15.540 | and then they brought them back

02:04:16.580 | after 12 hours of being awake,

02:04:18.820 | and no one seemed to have that light bulb moment

02:04:22.300 | of the sort of, "Okay, I get it."

02:04:25.500 | But then they did the same thing.

02:04:27.180 | They trained them, but now they train them in the evening.

02:04:28.980 | They gave them a full eight hours of sleep.

02:04:30.740 | They came back the next morning,

02:04:32.580 | and there was a three-fold increase

02:04:36.180 | in creative insight problem-solving ability.

02:04:38.980 | In other words, people were coming back

02:04:40.460 | with that aha moment of, "You know, the gig is up.

02:04:44.740 | "I've got it.

02:04:45.580 | "I know what you guys are trying to do,

02:04:47.180 | "and I'm going to show you."

02:04:48.580 | Then they did something clever.

02:04:50.700 | They said, "Back to our question of motor skill learning.

02:04:53.260 | "Well, is that really sleep, or is it just circadian,

02:04:56.340 | "that it's just something about going through the night

02:04:58.540 | "that gives you this kind of doolally creative benefit?"

02:05:02.220 | So they took another group.

02:05:03.180 | They taught them the information in the evening,

02:05:05.700 | and they tested them the next morning,

02:05:06.940 | just like the sleep group,

02:05:07.980 | but they kept them up all night.

02:05:09.300 | So they went through nighttime nurse for that time period,

02:05:12.340 | and they showed no benefit in the problem-solving.

02:05:15.940 | - Yeah, my experience is that sleep deprivation

02:05:17.940 | leads to all sorts of ideas

02:05:19.140 | about how one is coming up with novel ideas and solutions,

02:05:23.140 | all of which completely suck after two good nights' sleep.

02:05:26.580 | (laughing)

02:05:29.260 | But most of the time,

02:05:30.740 | it seems that sleep deprivation, intoxication of any kind,

02:05:35.980 | it gives one the impression

02:05:37.580 | that you're coming up with novel solutions,

02:05:39.420 | but really they're just novel.

02:05:41.380 | - Yeah, that data is very clear that there was this misnomer

02:05:44.460 | that if I sort of go through the night

02:05:47.220 | and work sort of through into the morning,

02:05:49.340 | I'm just much more creative when I'm sleep-deprived,

02:05:53.060 | and it's been tested, and it's just, it's the opposite,

02:05:56.620 | quite the opposite, in fact.

02:05:58.940 | What I also find interesting, though,

02:06:01.100 | about this sleep and creativity log,

02:06:04.300 | it was always there in the literature

02:06:06.700 | that there are innumerable anecdotes

02:06:09.180 | of people having sleep-inspired insight.

02:06:12.620 | It's almost as though when you wake up the next morning,

02:06:15.860 | having had that revised set of web connections in your brain,

02:06:20.580 | you can divine solutions

02:06:22.900 | to previously impenetrable problems.

02:06:26.340 | And there's a great example, I think, Dimitri Mendeleev,

02:06:29.620 | who at the time was trying to answer

02:06:33.540 | one of the most epic questions in human history.

02:06:36.380 | How do all of the known elements in the universe

02:06:39.700 | fit together in some logical order?

02:06:43.220 | And he was failing, he just could not.

02:06:45.540 | And he was so obsessed with this problem,

02:06:47.860 | he created playing cards

02:06:50.020 | with all of the different elements of the universe

02:06:52.740 | and their atomic weights and their electron,

02:06:55.380 | and he would go on these long train rides

02:06:57.860 | and he would just shuffle the cards

02:06:59.460 | and he would deal the cards on the table

02:07:01.500 | 'cause he was just desperate to try to see

02:07:03.460 | what the pattern was.

02:07:04.700 | He was shuffling and shuffling and shuffling.

02:07:06.940 | And then the story goes and it's written

02:07:08.660 | that one night he fell asleep and he dreamt

02:07:13.660 | and he could start to see all of the cards

02:07:17.940 | just dancing around in front of his eyes

02:07:20.420 | and then they snapped together in this logical grid

02:07:24.820 | based on the atomic weight

02:07:26.060 | and the different electron properties.

02:07:28.180 | And he wrote it down on the back of an envelope,

02:07:30.420 | which still exists to this date.

02:07:32.020 | - Really?

02:07:32.860 | - Yeah, and you can see it.

02:07:34.500 | And that was the initial basis

02:07:37.020 | for what we call the periodic table of elements.

02:07:40.300 | - Amazing.

02:07:41.140 | - And it revolutionized human history.

02:07:43.420 | And it's not just in science.

02:07:44.860 | I mean, there's great scientific,

02:07:46.420 | people have won Nobel prizes

02:07:47.780 | for understanding neural transmission, Otto Loewy.

02:07:50.580 | - Well, and maybe it's worth rattling off

02:07:53.020 | a few brief examples because they're so spectacular.

02:07:56.300 | Einstein was known for taking naps

02:07:58.060 | in the middle of the day,

02:07:59.100 | multiple times throughout the day

02:08:00.420 | in order to come up with novel solutions.

02:08:03.180 | I think the discovery of some of the organic--

02:08:08.180 | - The benzene ring?

02:08:10.260 | - The benzene ring came to, I'm forgetting.

02:08:13.740 | - August Kekulé.

02:08:14.580 | - In a dream, thank you.

02:08:16.300 | There are numerous examples

02:08:20.820 | of fundamental scientific discoveries

02:08:25.380 | that is creative insights

02:08:28.380 | that were anchored to real world experiments

02:08:31.540 | and theory, pure theory as well,

02:08:34.620 | that came to people in their dreams.

02:08:36.780 | So what's interesting though

02:08:37.940 | is that there seems to be some sort of hydraulic pressure

02:08:40.340 | created by the waking or within wakefulness attempt

02:08:44.580 | to like figure something out.

02:08:45.980 | So all of these people, to be very clear,

02:08:48.980 | didn't just sleep to come up with solutions.

02:08:51.140 | They put a lot of kind of hydraulic pressure

02:08:53.420 | feeding a lot of information,

02:08:54.900 | thinking about a problem

02:08:56.900 | in a structured or unstructured way,

02:08:58.620 | taking walks, focusing on their other demands of the day.

02:09:01.380 | But then when they went to sleep,

02:09:02.660 | clearly that information was still being worked with

02:09:05.420 | in important ways.

02:09:06.740 | And then you were going to mention some examples

02:09:09.140 | from the arts, I think.

02:09:10.940 | - Yeah, there's some great,

02:09:12.420 | I was born and raised in Liverpool, in England,

02:09:16.980 | and of course, famous for the Beatles

02:09:19.300 | and for Liverpool Football Club and Everton as well,

02:09:22.980 | but I'm a Liverpool supporter.

02:09:24.300 | However, Paul McCartney has gone on record very clearly

02:09:27.980 | to say that two songs that were probably

02:09:31.220 | some of the most successful songs,

02:09:34.140 | "Yesterday" and "Let It Be",

02:09:36.140 | both came to him by way of dream-inspired insight.

02:09:39.220 | There's a lovely description, I think, in his biography.

02:09:41.660 | He was filming, it was either "Help"

02:09:44.140 | or "A Hard Day's Night" down in London

02:09:46.980 | with the rest of the Beatles.

02:09:48.300 | And he was staying in a rental in Wimpole Street in London.

02:09:51.700 | And he was staying on the third floor.

02:09:53.220 | And in his bedroom, fortunately,

02:09:54.980 | there was a piano on the opposite side of the room.

02:09:57.860 | And he describes how he woke up one morning

02:10:00.740 | with this beautiful melody by way of,

02:10:05.700 | it was a string quartet that was playing it.

02:10:08.220 | And it was the melody for "Yesterday".

02:10:11.860 | And he went straight over to the piano

02:10:13.700 | and he started playing it.

02:10:15.500 | And he said, it was just so sumptuous.

02:10:17.780 | And he couldn't remember where he had heard it.

02:10:21.420 | And then after a while he remembered,

02:10:23.180 | I haven't heard it anywhere before.

02:10:25.060 | It came to me by way of sleep.

02:10:27.740 | Same thing with "Let It Be".

02:10:31.220 | Obviously, Mother Mary comes to me singing songs

02:10:37.100 | or singing words of wisdom, "Let It Be".

02:10:39.580 | And there's often been a suggestion

02:10:41.180 | that that has religious overtones in terms of Mother Mary.

02:10:45.100 | It actually is not.

02:10:46.300 | It's his mother, Mary McCartney.

02:10:51.020 | And he was having a hard time struggling

02:10:52.820 | with the fame of the Beatles at that moment.

02:10:55.340 | And one night he slept and his mother, Mary,

02:10:58.220 | came to him and just said, relax, it's going to be okay.

02:11:01.900 | Stay true to yourself, continue doing what you're doing.

02:11:05.820 | Just let it be.

02:11:07.100 | And he woke up and he wrote the song.

02:11:08.940 | - I love that story.

02:11:10.380 | And there's some actionable takeaways here that if I may,

02:11:15.260 | I just wanted to mention.

02:11:20.180 | A previous guest on this episode,

02:11:21.500 | in fact, he's been on the podcast twice,

02:11:23.700 | is the great Rick Rubin.

02:11:25.900 | - Oh, I've listened to those.

02:11:27.260 | - Yeah, one of the most legendary music producers

02:11:30.260 | of all time.

02:11:31.100 | And the second episode that we did with Rick,

02:11:33.220 | he gets heavily into some of his protocols

02:11:36.180 | for lack of a better way to describe them.

02:11:38.060 | And one of the things that Rick does

02:11:40.620 | is when he wakes up in the morning,

02:11:42.180 | he makes it a point to, he takes walks, he gets sunshine,

02:11:47.180 | he hydrates, he does all of those things.

02:11:49.340 | But to try and make the transition between sleep

02:11:51.860 | and wakefulness to be rather gradual,

02:11:54.340 | almost to allow some of the components of sleep

02:11:58.620 | to kind of bleed into the morning

02:12:01.700 | and then allow wakefulness to come about.

02:12:04.300 | And in his case, he's able to push some of the more

02:12:07.500 | linear processing and procedural things

02:12:09.980 | to later in the day.

02:12:11.940 | And I've spent a lot of time with Rick.

02:12:13.900 | I'm fortunate to be close friends with Rick.

02:12:15.580 | And I can tell you that he also spends a fair amount of time

02:12:18.620 | sitting or lying down typically very still

02:12:21.540 | with his eyes closed,

02:12:22.540 | just thinking or allowing thoughts to emerge

02:12:24.980 | as part of his creative process.

02:12:27.900 | Now, he's certainly not the only one to do this,

02:12:30.980 | but he's a notable example.

02:12:33.200 | But what's the takeaway here?

02:12:34.780 | Should everyone be lying with their eyes closed

02:12:37.420 | when they first wake up?

02:12:38.420 | Perhaps, but there's some potential do's,

02:12:41.180 | but I think there's a really strong don't.

02:12:43.900 | If one subscribes to the idea that during sleep

02:12:47.100 | there is substantial reorganization of neural circuitry,

02:12:50.340 | aka learning, but also expansion of creative opportunity,

02:12:54.160 | as you've clearly pointed out,

02:12:56.220 | and there are data to support that statement,

02:12:58.540 | then it stands to reason that upon waking,

02:13:01.940 | there's a key opportunity to capture some of that

02:13:05.620 | information that is now in your mind

02:13:10.860 | that was created the night before,

02:13:12.180 | but that if you immediately look at your phone,

02:13:16.140 | that you eclipse that process

02:13:19.220 | with sensory input from somebody else's ideas

02:13:21.660 | and what's going on in the world.

02:13:22.900 | And it's not to say that looking at your phone

02:13:24.040 | first thing in the morning is a cardinal sin

02:13:26.320 | or a violation of any kind of neural circuit requirement,

02:13:29.820 | but I, in an attempt to try and capture

02:13:32.200 | some of the learning and creativity

02:13:33.720 | that occurs during sleep,

02:13:35.260 | have tried for a while now to not look at my phone

02:13:38.220 | for at least the first 30 minutes after waking.

02:13:40.140 | It's very challenging to do for most everybody,

02:13:43.420 | but rather to let some of the ideas from sleep percolate up.

02:13:47.940 | And I will often go, you know, be, you know,

02:13:50.380 | making a morning cup of tea or something,

02:13:52.500 | and then go running to my office to write something down

02:13:55.660 | that suddenly springs to mind.

02:13:56.700 | And then I'll remember that this was something

02:13:58.340 | that came to me in a dream the night before,

02:13:59.900 | none of which is significant as the benzene ring

02:14:01.820 | or the periodic table or the kind of works

02:14:03.620 | that Rick has produced.

02:14:05.020 | But I think that we need to be cautious

02:14:07.740 | about not short-circuiting these creative insights

02:14:13.220 | that no doubt can come to us in sleep.

02:14:15.260 | - I think it's very well worth just,

02:14:17.820 | even for your own mental health,

02:14:19.420 | firstly, not to just wake up

02:14:21.460 | and start your reception of the world,

02:14:24.420 | but to do some, as we've mentioned,

02:14:26.260 | reflection on what you've just experienced

02:14:29.220 | by way of sleeping.

02:14:30.460 | And it doesn't necessarily have to be

02:14:32.060 | that you're trying to recall your dreams.

02:14:34.280 | Just sit with whatever your thoughts are.

02:14:36.740 | Think about the day ahead, think about the days prior,

02:14:40.660 | and there is some benefit.

02:14:42.060 | And the creative benefit there, you mentioned Einstein.

02:14:46.460 | Another one that is often mentioned to me is Edison,

02:14:50.140 | Thomas Edison, the inventor.

02:14:51.740 | And Edison was claimed to be a short sleeper.

02:14:54.660 | People will say, well, he was a brilliant inventor,

02:14:57.620 | but you said that he didn't sleep very much.

02:15:00.940 | It turns out that Edison was a habitual napper

02:15:03.740 | during the day.

02:15:04.580 | And I've got lots of pictures of him napping

02:15:07.180 | on his workbench in his studio, him napping in the garden.

02:15:11.620 | - Oh, I love it.

02:15:12.460 | Well, I took a 45-minute nap today.

02:15:14.780 | - Yeah, and it was, he--

02:15:16.340 | - And I'm no Edison, but I subscribe to his protocols.

02:15:20.200 | - But, you know, he understood the creative brilliance

02:15:24.820 | of sleep, to your point, about writing things down,

02:15:28.140 | and he used it ruthlessly as a tool.

02:15:30.260 | And here's what he would do.

02:15:31.180 | It's genius.

02:15:32.300 | He would take a pair of steel ball bearings

02:15:35.340 | in his right hand, and he would sit in his office

02:15:38.100 | on a reclining chair with a rest for his arm.

02:15:41.500 | And then he would put a pad of paper and a pen next to him.

02:15:45.060 | And then he would gradually start to relax off.

02:15:47.960 | But what he'd done was he used a metal saucepan

02:15:52.060 | and turned it upside down

02:15:53.100 | and placed it underneath the armrest.

02:15:55.300 | And as he was drifting off into that state,

02:15:57.820 | into that sort of liminal state,

02:15:59.500 | so he didn't go too far into sleep,

02:16:02.140 | what would happen is that his muscle tone

02:16:03.900 | would gradually relax.

02:16:05.140 | He would release the steel ball bearings.

02:16:07.260 | They would crash on the saucepan, wake him up,

02:16:09.660 | and he would start to write down all of the ideas

02:16:12.740 | that he was having from that liminal state.

02:16:14.540 | - Oh, you said saucepan.

02:16:16.100 | - Saucepan, sorry.

02:16:16.940 | - That's why, no, no, that's okay.

02:16:18.380 | But you're very-- - Bad accent.

02:16:20.420 | - So it made a clanging sound.

02:16:23.060 | - A metal saucepan underneath.

02:16:24.300 | - Got it, got it.

02:16:25.140 | - Or a water pail, whatever it was.

02:16:27.180 | And it would crash there, wake him up,

02:16:29.300 | and then he would write down these ideas.

02:16:30.820 | - So interesting.

02:16:31.660 | - And in fact, if you look at his house,

02:16:34.440 | which is preserved, historical, you can walk around,

02:16:37.340 | and he had nap cots installed in his house,

02:16:41.700 | so he could go into different rooms

02:16:43.420 | and take naps in these little cots.

02:16:45.540 | - Listen, I-- - For his genius,

02:16:46.780 | but it's brilliant, isn't it?

02:16:48.620 | - It is brilliant.

02:16:49.460 | Sorry, I didn't mean to interrupt,

02:16:50.380 | but it was out of enthusiasm.

02:16:51.940 | I mean, I don't want to give too much detailed information

02:16:56.020 | about Rick's working environment,

02:16:57.700 | but yeah, let's just say there are a lot of places

02:16:59.300 | to lie down and access these states of mind.

02:17:04.100 | And it looks like somebody just lying there

02:17:07.140 | with their eyes closed,

02:17:07.980 | but there's an extremely active mind in there.

02:17:10.760 | Obviously, look at the productive output of Rick's career

02:17:14.980 | is truly something to behold.

02:17:17.420 | Behold in capital, bold, underlined, highlighted letters.

02:17:20.480 | But it's so clear to me, based on all the examples you gave,

02:17:26.180 | the ones that we're kind of batting back and forth now,

02:17:28.100 | and I think there's a book,

02:17:29.460 | the title is something like Winston Churchill's Nap

02:17:32.980 | or something like that.

02:17:34.140 | Then my dad is always talking,

02:17:35.180 | my dad's a theoretical physicist,

02:17:36.420 | always talks about napping is so key

02:17:39.180 | to one's ability to come up with novel solutions.

02:17:42.760 | I guess that napping frequently throughout the day

02:17:46.300 | perhaps violates some of the tenets

02:17:48.420 | that you described in the episode

02:17:52.640 | on napping and caffeine, episode three.

02:17:55.720 | - I think you agree 'cause we put in guardrails

02:17:58.140 | and we put in the protocols to say,

02:17:59.700 | okay, naps under certain circumstances

02:18:02.340 | are no bad thing at all.

02:18:03.540 | And if you're going to do it,

02:18:04.380 | here are the suggested guidelines

02:18:06.460 | as to exactly how you optimize naps with a protocol.

02:18:10.220 | But it is, I think it's very worthwhile

02:18:13.740 | to just appreciate exactly how complex sleep is

02:18:17.720 | in terms of what it's doing for information processing.

02:18:21.300 | And if you were to ask me,

02:18:22.140 | look, what's the take home of this final section?

02:18:25.500 | I think it's, no one has ever told you,

02:18:30.100 | Andrew, you really need to stay awake on a problem.

02:18:34.280 | They've told you that you should sleep.

02:18:36.060 | - No, many times.

02:18:36.980 | - On a problem.

02:18:37.820 | - Go to sleep.

02:18:38.640 | - Yeah, sleep on a problem.

02:18:39.700 | And what's interesting is that in every language

02:18:42.040 | that I've inquired about today,

02:18:44.180 | from English to Swahili,

02:18:47.840 | that phrase, sleeping on a problem,

02:18:49.700 | or something like it, very much exists.

02:18:52.360 | I think the Spanish someone was telling me is,

02:18:55.120 | translated is, you have a conversation with your pillow,

02:18:58.000 | which I thought was lovely.

02:18:59.540 | What I also was struck by a fellow

02:19:03.140 | who was French said, you in England,

02:19:06.900 | you say you sleep on a problem.

02:19:09.900 | Well, the French translation is much closer to you

02:19:12.020 | sleep with a problem.

02:19:13.740 | And I thought that says so much about the romantic difference

02:19:18.240 | between the beautiful French and the English.

02:19:21.380 | You sleep on a problem versus you sleep with a problem.

02:19:24.580 | - Yes, I agree.

02:19:25.420 | I think not only does it have more romantic notions,

02:19:28.660 | but I like it because there's a symbiotic aspect

02:19:33.660 | to sleeping with the problem.

02:19:35.860 | There's kind of a meshing with the challenge

02:19:38.660 | in a way that isn't as combative.

02:19:43.020 | Like this thing that's weighing on you,

02:19:44.420 | you go to sleep with and you're supposed to wake up

02:19:46.100 | and feel like you've solved it, like Eureka, right?

02:19:49.180 | - Push down on it rather than it's a collaboration

02:19:51.460 | with sleep rather than a demand from it.

02:19:54.660 | But I also think it's,

02:19:56.540 | I make that notion about language translation

02:19:59.780 | and maybe a slight joke,

02:20:01.420 | but what it also tells me is this,

02:20:04.380 | that that phenomenon of sleep dependent creativity

02:20:09.260 | transcends cultural boundaries.

02:20:11.220 | It is common across the globe.

02:20:13.380 | It's a universal phenomenon.

02:20:15.380 | Why?

02:20:16.300 | Well, because sleep is a universal phenomenon,

02:20:19.020 | not just even in humans,

02:20:20.860 | but in almost every species

02:20:22.360 | that we've studied carefully today.

02:20:25.620 | - As you described the French notion

02:20:30.220 | of sleeping with a problem,

02:20:31.340 | I think one of the images that comes to mind

02:20:33.500 | is that perhaps the idea is

02:20:35.660 | if you're going to sleep with a problem

02:20:37.660 | that you should be the big spoon

02:20:39.900 | and they should be the little spoon,

02:20:41.340 | as opposed to the problem being the big spoon

02:20:44.340 | and you're kind of wrapped in the problem.

02:20:46.140 | Maybe the problem needs to mesh with you,

02:20:48.140 | but maybe I'm taking this imagery a little too far.

02:20:51.540 | Before we close out this discussion

02:20:53.540 | about sleep and creativity,

02:20:55.580 | I can't help but bring up a set of questions

02:20:59.140 | around a different non-sleep protocol

02:21:03.820 | that in many ways seems to mimic sleep

02:21:07.180 | and that for some individuals throughout history,

02:21:10.260 | in particular, the great physicist Richard Feynman,

02:21:12.760 | another habitual napper.

02:21:15.740 | - Yeah, and an absolute idol of mine.

02:21:17.920 | - Wrote about and spoke about his fondness

02:21:22.860 | for these flotation tanks

02:21:25.660 | that contain a temperature of water

02:21:28.980 | that is fairly neutral.

02:21:30.820 | So one doesn't recognize the difference

02:21:32.940 | between body temperature and the surrounding water.

02:21:35.660 | And there's a certain amount of salt salinity in the water

02:21:39.620 | that allows one to float at a kind of a depth

02:21:43.980 | within the water that one loses their sense

02:21:46.260 | of proprioceptive awareness,

02:21:48.340 | as you described earlier in the series,

02:21:51.300 | a key component of falling asleep.

02:21:53.300 | And he talked about how under those conditions

02:21:56.440 | in the flotation tank,

02:21:57.700 | there was a kind of an untethering

02:22:00.340 | of one's notions of space and time

02:22:02.960 | that were very sleep-like

02:22:04.140 | and that that was one of his go-tos for creative solutions.

02:22:09.140 | People talked about walks

02:22:11.700 | as a go-to for creative solutions.

02:22:15.480 | In the shower,

02:22:16.460 | people seem to come up with creative solutions.

02:22:18.980 | States of mind where they're in activities

02:22:22.960 | where it's only somewhat goal-directed,

02:22:27.420 | but basically the idea is to just lose track

02:22:30.180 | of one's body positioning and let the mind go, so to speak.

02:22:34.180 | And for that matter,

02:22:35.020 | psychedelics have on occasion been attributed

02:22:38.900 | as at least one of the sources of creative solutions.

02:22:42.180 | I raised these ideas,

02:22:43.560 | understanding that each one of those

02:22:44.980 | could be a podcast into itself.

02:22:47.180 | But it seems to me that sleep,

02:22:50.520 | and in particular dream sleep,

02:22:54.100 | is nature's way of creating these states of untethering,

02:22:59.100 | our rigid, linear understanding of what relates to what.

02:23:04.580 | And it provides this near magical mixing

02:23:08.300 | of things learned the day before.

02:23:10.300 | And that's the essence of creativity.

02:23:12.860 | And humans have been trying to tap into the creative process

02:23:15.000 | through all these other portals for a long time

02:23:16.740 | with expensive technologies.

02:23:19.580 | But it's becoming very clear to me

02:23:21.920 | that the technology already exists

02:23:24.580 | and that it costs absolutely nothing.

02:23:26.900 | And that it has tremendous health benefits

02:23:29.000 | in addition to its benefits for creativity.

02:23:33.760 | And that technology is this brilliant technology of sleep.

02:23:38.760 | - Yeah, and dreaming.

02:23:39.980 | It's a stunning state.

02:23:42.380 | - Matt, thank you so much for today's discussion

02:23:45.700 | about sleep, memory, learning, and creativity.

02:23:50.500 | We are now four episodes into this series on sleep.

02:23:55.500 | First episode, we discussed,

02:23:59.420 | rather, you taught us about sleep

02:24:03.220 | and the biology of sleep,

02:24:04.720 | as well as some actionable takeaways.

02:24:07.620 | So actually some, I would say,

02:24:09.380 | some important guidelines for getting one's sleep correct.

02:24:14.840 | And then in this second episode,

02:24:17.240 | you went much further into protocols,

02:24:19.600 | both basic and advanced for getting one's sleep right,

02:24:22.440 | maybe even optimized.

02:24:24.560 | And the third episode, you taught us about naps and caffeine.

02:24:29.440 | And today you've taken us on a beautiful exploration

02:24:33.280 | of the relationship between sleep and learning.

02:24:36.680 | What's more interesting than neuroplasticity and learning?

02:24:39.220 | I mean, after all, you know,

02:24:42.160 | humans are unique in our ability to learn

02:24:44.400 | so many things throughout the lifespan.

02:24:46.400 | It's one of the things that distinguishes us

02:24:48.080 | from the other species on the planet,

02:24:49.400 | the very, very long window,

02:24:52.640 | perhaps lifelong window for the opportunity to learn.

02:24:55.640 | And of course, creativity and novel solutions

02:24:59.360 | to challenging problems in the world,

02:25:00.720 | but also great works of art and music, et cetera.

02:25:05.080 | I think we can fairly say,

02:25:06.720 | based on what you've taught us today,

02:25:07.900 | that sleep has been not only the bedrock

02:25:10.960 | of mental health, physical health and performance

02:25:13.080 | since the beginning of time and still now,

02:25:14.480 | but also has been one of the fundamental drivers

02:25:17.720 | of human evolution because of all the creative insights

02:25:19.960 | that have occurred and all the learning

02:25:21.280 | that's occurred in sleep that's then been transformed

02:25:25.200 | into real world technologies.

02:25:26.880 | Indeed, it's much of the way that we have the blessing

02:25:30.800 | of being right here, right now.

02:25:32.560 | - If that's the flag that you're raising,

02:25:34.100 | I will salute it five ways till Tuesday very much, yes.

02:25:38.200 | - Well, I'll salute that flag right with you

02:25:41.120 | and also point to the exciting fact

02:25:44.580 | that the next episode, episode five in this series,

02:25:48.320 | you're going to teach us about the really tight relationship

02:25:52.480 | between sleep and emotional processing and emotionality.

02:25:57.400 | And I can't think of a more interesting topic to get into,

02:26:00.600 | especially at this point in the series.

02:26:02.720 | And I look forward to that discussion

02:26:05.080 | with emotional enthusiasm.

02:26:08.040 | I can't wait.

02:26:08.880 | If folks are interested in trying to modulate

02:26:11.880 | their mental health, I think that next discussion

02:26:14.960 | should be very helpful with regard to sleep.

02:26:17.160 | I hope so at least.

02:26:18.760 | - Thank you for joining me for today's episode

02:26:20.600 | with Dr. Matthew Walker.

02:26:22.160 | To learn more about Dr. Walker's research

02:26:24.360 | and to learn more about his book

02:26:25.960 | and his social media handles,

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Dr. Matt Walker: Using Sleep to Improve Learning, Creativity & Memory | Huberman Lab Guest Series

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