Using Science to Optimize Sleep, Learning & Metabolism

00:00:00.000 | - Welcome to the Huberman Lab Podcast,

00:00:02.280 | where we discuss science and science-based tools

00:00:04.920 | for everyday life.

00:00:05.920 | I'm Andrew Huberman,

00:00:10.800 | and I'm a professor of neurobiology and ophthalmology

00:00:13.400 | at Stanford School of Medicine.

00:00:15.560 | This podcast is separate from my teaching

00:00:17.440 | and research roles at Stanford.

00:00:19.440 | It is, however, part of my desire and effort

00:00:21.620 | to bring zero cost to consumer information

00:00:23.840 | about science and science-related tools

00:00:25.920 | to the general public.

00:00:27.660 | Along those lines, I want to thank the sponsors

00:00:29.720 | of today's podcast.

00:00:31.280 | Our first sponsor is Athletic Greens,

00:00:33.320 | which is an all-in-one vitamin mineral

00:00:35.900 | probiotic liquid supplement.

00:00:38.080 | I've been using Athletic Greens since 2012,

00:00:41.540 | because I really like getting

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00:00:49.960 | I've mixed mine with a little bit of lemon juice.

00:00:51.480 | I've been doing that well for well over a decade now.

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00:01:08.580 | If you want to try Athletic Greens,

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00:01:20.180 | Vitamin D3 has been shown to be important

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00:01:27.340 | And so once more, if you want to try Athletic Greens

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00:01:32.400 | just go to athleticgreens.com/huberman.

00:01:36.260 | The other sponsor of today's podcast is Inside Tracker.

00:01:39.580 | Inside Tracker is a way to measure metabolic factors,

00:01:44.580 | hormones, and DNA-related factors by way of blood tests

00:01:49.580 | and saliva in order to assess one's health.

00:01:52.900 | I'm a big believer in blood tests and saliva tests

00:01:55.940 | for assessing one's health markers because I like data.

00:01:59.920 | And there's really no other way to measure what's going on

00:02:03.100 | in one's body without taking the occasional blood test

00:02:06.940 | or saliva test.

00:02:08.260 | You can guess what's going on,

00:02:10.220 | but if you really want to know what's going on

00:02:11.940 | under the hood, Inside Tracker can be of great help.

00:02:15.660 | One of the problems with a lot of products out there,

00:02:18.300 | or just regular blood testing,

00:02:19.660 | is that you get a lot of data back

00:02:21.180 | about the levels of various hormones, metabolic factors,

00:02:23.480 | et cetera, but you don't know what to do with those data.

00:02:25.900 | Great thing about Inside Tracker is it is provided

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00:02:35.020 | directs you toward potential lifestyle-related changes

00:02:39.340 | like changes in exercise or changes in sleep patterns

00:02:43.180 | or changes in nutritional patterns

00:02:45.600 | that can really help move those markers and those numbers

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00:02:51.100 | in the direction that you want.

00:02:52.960 | If you'd like to try Inside Tracker,

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00:03:02.700 | Okay, let's get started.

00:03:04.620 | Today is episode three of the podcast,

00:03:06.680 | and it is office hours.

00:03:08.420 | Office hours, as many of you know,

00:03:10.620 | is where students come to the office of the professor,

00:03:13.380 | sit down and ask questions, requesting clarification

00:03:16.680 | about things that were confusing,

00:03:18.640 | or to simply go down the route of exploring a topic

00:03:22.840 | with more depth and detail.

00:03:25.200 | I asked for your questions to be listed

00:03:27.760 | in the comment section of the previous two episodes

00:03:30.060 | of the podcast on YouTube, as well as on Instagram.

00:03:33.140 | And I, first of all, just want to thank you

00:03:35.020 | for the many questions.

00:03:36.260 | They are excellent.

00:03:37.780 | We read them all.

00:03:39.160 | We distilled from that large batch of questions

00:03:43.200 | to two types of questions,

00:03:45.460 | questions that were asked very often

00:03:47.380 | and were liked very often with a little thumbs up like tab,

00:03:51.360 | as well as questions that we thought could really expand

00:03:53.660 | on the topics that we've covered previously.

00:03:56.460 | And today we're going to cover both of those.

00:03:59.520 | If we did not get to your question, please don't despair.

00:04:03.860 | We will keep track of those.

00:04:05.240 | And we have several more episodes devoted to this topic

00:04:08.580 | of sleep and wakefulness and learning

00:04:11.440 | during the month of January, maybe even, you know,

00:04:14.340 | leaking over a little bit into the month of February.

00:04:16.380 | So we have time.

00:04:17.780 | That's one of the unique formats of this podcast

00:04:19.780 | is that we have time for dialogue.

00:04:21.700 | We have time for your questions

00:04:22.940 | and we have time to really go deep into these topics.

00:04:26.460 | It's official, Costello is sleeping in the background.

00:04:28.820 | So if you hear snoring, Costello is going to be keeping time

00:04:33.140 | with his deep and melodic snoring.

00:04:36.380 | There he goes.

00:04:37.460 | So the questions that we received,

00:04:40.740 | I batched crudely into a couple of different categories.

00:04:44.780 | Light, exercise, supplementation,

00:04:48.180 | temperature, learning, plasticity, and mood,

00:04:53.300 | and sort of mood related disorders.

00:04:55.140 | There were a lot of questions about those.

00:04:56.940 | Before we begin any of this,

00:04:58.600 | I want to point out something that I always say,

00:05:00.860 | it sounds like boilerplate,

00:05:02.460 | but it's important not just to protect me,

00:05:04.300 | but to protect you, which is that I am not a physician.

00:05:07.340 | I'm not a medical doctor.

00:05:08.340 | I don't prescribe anything, including behavioral protocols.

00:05:11.620 | I'm a professor.

00:05:12.460 | I profess a lot of things based on quality peer-reviewed

00:05:15.060 | studies.

00:05:16.660 | You should take that information.

00:05:18.060 | You should filter it through whatever it is

00:05:20.080 | that you currently happen to be dealing with,

00:05:22.620 | whether or not that's health or illness.

00:05:24.180 | You should consult with a licensed healthcare professional

00:05:27.900 | before you add or remove anything

00:05:30.660 | from your daily life protocol.

00:05:32.240 | I'm not responsible for your health, you are.

00:05:35.500 | So be smart with this information

00:05:37.600 | and be a stringent filter, as we say.

00:05:42.320 | Okay, very well.

00:05:43.160 | Let's get started on the actual material.

00:05:45.320 | Somebody asked, what is the role of moonlight and fire?

00:05:51.240 | I'm presuming they mean fireplace or candle

00:05:54.980 | or things of that sort.

00:05:56.440 | In setting circadian rhythms,

00:05:58.480 | is it okay to view moonlight at night

00:06:01.280 | or will that wake me up?

00:06:02.680 | Will a fire in my fireplace

00:06:04.780 | or using candlelight be too much light?

00:06:07.860 | Great question.

00:06:09.300 | Also offers me the opportunity to share with you

00:06:11.900 | what I think is a quite beautiful definition

00:06:14.280 | of what light is in a quantitative sense.

00:06:17.700 | So I've mentioned a few times the use of apps

00:06:21.300 | and light meters and things to measure things like lux,

00:06:24.880 | which sometimes are also described in terms of candelas.

00:06:28.620 | So those are the two units for measuring light intensity.

00:06:31.560 | Typically lux, L-U-X, is the unit.

00:06:34.940 | And so before we go forward and discuss this many lux

00:06:37.700 | or that many lux, I want to just tell you what a lux is

00:06:40.980 | because it relates to this question.

00:06:42.760 | One lux equals the illumination of one square meter surface

00:06:47.760 | at one meter away from a single candle.

00:06:51.940 | So somebody actually decided at some point

00:06:55.740 | that the amount of illumination at one square meter surface,

00:07:00.260 | one meter away from a single candle, that equals one lux.

00:07:03.800 | So when we talk about 6,000 lux of light intensity

00:07:08.000 | or 10,000 lux of light intensity,

00:07:10.200 | now you have a kind of a reference or a framework

00:07:13.120 | that would be the equivalent of,

00:07:14.680 | you could think of it as 6,000 candles

00:07:16.920 | all with their light intensity shown on one square meter

00:07:20.680 | from one meter's distance away.

00:07:22.800 | Or of course, if it was a different number of lux,

00:07:24.880 | it would be a different number of candles.

00:07:26.400 | So you get the idea.

00:07:27.800 | Here's the great thing.

00:07:29.680 | It turns out that moonlight, candlelight,

00:07:33.280 | and even a fireplace,

00:07:34.580 | if you have one of these roaring fires

00:07:35.940 | going in the fireplace,

00:07:37.680 | do not reset your circadian clock at night

00:07:41.080 | and trick your brain into thinking that it's morning.

00:07:44.040 | Even though if you've ever sat close to a fireplace

00:07:46.980 | or even a candle, that light seems very bright.

00:07:50.040 | And there are two reasons for that that are very important.

00:07:52.860 | The first one is that these neurons in your eye

00:07:56.280 | that I discussed in the previous episode,

00:07:58.040 | these melanopsin ganglion cells,

00:08:00.620 | also called intrinsically photosensitive ganglion cells,

00:08:03.920 | those cells adjust their sensitivity across the day.

00:08:07.940 | And those cells respond best to the blue-yellow contrast

00:08:11.280 | present in the rising and setting sun,

00:08:13.820 | so-called low solar angle sun,

00:08:15.740 | also discussed in the previous episode.

00:08:17.960 | But those cells adjust their sensitivity

00:08:20.400 | such that they will not activate the triggers in the brain

00:08:25.400 | that convey daytime signals when they view moonlight,

00:08:30.760 | even a full moon, a really bright moon,

00:08:33.560 | or fire.

00:08:34.480 | Now, this does raise an interesting kind of thought point,

00:08:37.200 | which is a lot of people have talked about lunacy

00:08:39.960 | and the fact that when there's a full moon out,

00:08:41.520 | people act differently and behave differently.

00:08:44.000 | There's a lot of lore around that.

00:08:45.340 | There's actually a little bit of quality science around that

00:08:47.420 | that maybe we can address in the future.

00:08:49.280 | But moonlight is typically not going to wake us up too much,

00:08:54.280 | except maybe if the moon is really full and really bright,

00:08:57.400 | there's possibility for that.

00:08:58.980 | So provided you're not going to burn down

00:09:01.040 | the structure you're in,

00:09:02.060 | you're not going to burn down the forest,

00:09:03.320 | enjoy your fireplaces, enjoy your lights from candles,

00:09:08.080 | and those are perfectly safe

00:09:09.560 | without disrupting your circadian rhythm.

00:09:11.280 | Because we talked about just how crucial it is

00:09:13.720 | to avoid bright lights

00:09:14.760 | between the hours of about 10 PM and 4 AM,

00:09:17.720 | except when you need to view things for sake of safety

00:09:21.360 | or work and so forth.

00:09:24.480 | I also received a lot of questions about red light.

00:09:27.560 | Now, I think I was asked those questions

00:09:29.220 | because red light is used

00:09:31.760 | in a number of different commercial products

00:09:33.920 | where these products tend to include

00:09:36.200 | a sheet of very bright red lights

00:09:38.600 | that one is supposed to view early in the day.

00:09:41.440 | And there are various claims attached

00:09:43.320 | to these red light devices

00:09:45.080 | that they improve mitochondrial function,

00:09:46.920 | that they improve metabolism.

00:09:48.360 | I'm going to be really honest and I can't name brands

00:09:52.320 | and I'm not going to name particular studies

00:09:54.400 | 'cause what I'm about to say about these studies

00:09:56.180 | is not particularly unkind,

00:10:00.520 | but let's just say that none of the studies that I've seen,

00:10:03.560 | except for one that I'll talk about in a moment,

00:10:06.700 | pointing to the positive effects of red light

00:10:09.320 | on the visual system

00:10:10.720 | are published in blue ribbon journals.

00:10:13.800 | They tend to be published in journals

00:10:15.220 | that I had to work hard to find.

00:10:17.920 | I'm not sure what the peer review and stringency level is.

00:10:21.120 | Now, that's not to say red light isn't beneficial

00:10:23.000 | because there is one study in particular

00:10:25.320 | that came from Glen Jeffrey's lab

00:10:26.800 | at the University of College London.

00:10:28.160 | It was published last year.

00:10:30.200 | Glen is somebody I happen to know.

00:10:31.920 | He has an excellent reputation, excellent vision scientist.

00:10:35.600 | What this study essentially showed,

00:10:37.380 | and again, this is a study that I very much like the data

00:10:40.760 | and think it was done with very high standards.

00:10:43.160 | What this study shows is that viewing red light

00:10:47.680 | for a few minutes each morning

00:10:50.080 | can have positive effects on mitochondria

00:10:54.160 | in a particular retinal cell type

00:10:56.140 | that tends to degenerate or decline in function

00:10:58.840 | with age in humans.

00:11:00.160 | And that cell type is the photoreceptor.

00:11:02.920 | The photoreceptor is a type of cell in your eye

00:11:06.360 | that sits at the back of the eye.

00:11:08.000 | It's kind of some distance away from the ganglion cells.

00:11:10.560 | And it's the cell that converts light information

00:11:12.980 | into electrical signals that the rest of the retina

00:11:15.520 | and brain can understand.

00:11:17.360 | These are vitally important cells.

00:11:19.140 | Without them, people are blind.

00:11:21.160 | And many people's vision gets worse with age,

00:11:24.720 | in particular age-related macular degeneration,

00:11:26.740 | but also related to some other factors,

00:11:29.240 | including photoreceptor functionality,

00:11:32.480 | just getting worse with time.

00:11:33.720 | And what Glenn showed was that red light flashes delivered,

00:11:38.560 | in particular early in the day, but not late in the day,

00:11:41.360 | can help repair the mitochondria.

00:11:43.560 | Now, this study needs more support

00:11:46.860 | from additional studies, of course.

00:11:48.780 | They are doing a clinical trial.

00:11:50.040 | They did report on what I think it was 12 patients.

00:11:53.000 | And so the work is ongoing, but that was very interesting.

00:11:56.700 | And it points to some potentially

00:11:59.080 | really useful things about red light.

00:12:01.480 | However, most of the questions I got about red light

00:12:04.640 | for sake of office hours

00:12:06.100 | were about the use of red light later in the day.

00:12:08.500 | So here's the deal.

00:12:09.340 | In principle, red light will not stimulate the melanopsin

00:12:13.840 | retinal neurons that wake up the brain and circadian clock

00:12:17.200 | and signal daytime.

00:12:19.000 | However, most of the red lights,

00:12:20.480 | in particular the red lights that come on these sheets

00:12:22.640 | of these products that people are supposed to view them

00:12:25.360 | in order to access a number of proclaimed health effects,

00:12:29.700 | those are way too bright

00:12:31.380 | and would definitely wake up your body and brain.

00:12:34.380 | So if you're going to use those products,

00:12:36.240 | and I'm not suggesting you do or you don't,

00:12:38.260 | but if that's your thing,

00:12:39.640 | you would want to use those early in the day.

00:12:41.180 | Who knows, you might even derive some benefit

00:12:43.020 | on mitochondrial function in these photoreceptors.

00:12:46.140 | But if you're thinking about red light

00:12:48.220 | for sake of avoiding the negative effects of light

00:12:51.060 | later in the day and at night,

00:12:53.040 | then you want that red light to be very, very dim,

00:12:55.420 | certainly much dimmer than is on most

00:12:57.940 | of those commercial products.

00:13:00.120 | Now, do you need red lights?

00:13:01.640 | No, although red lights are rather convenient

00:13:03.580 | because you can see pretty well with them on,

00:13:05.820 | but if they're dim, they won't wake up the circadian clock.

00:13:08.740 | They won't have this dopamine disrupting thing

00:13:11.320 | that we talked about in the previous podcast.

00:13:13.140 | So there's a role for red light potentially early in the day

00:13:15.900 | and for mitochondrial repair in the photoreceptors.

00:13:18.660 | There's a role for dim red light

00:13:20.900 | later in the day and at night.

00:13:22.540 | So you're starting to notice a theme here,

00:13:24.020 | which is that there's no immediate prescription

00:13:26.740 | of look at these lights.

00:13:28.080 | It's look at these lights potentially,

00:13:30.260 | if that's what you want to do,

00:13:31.600 | at particular times of day and with particular intensities.

00:13:34.380 | It brings us back to the blue light issue,

00:13:36.000 | which is so many people are obsessed

00:13:37.340 | with avoiding blue light,

00:13:38.560 | but you actually want a ton of blue light

00:13:39.960 | early in the day and throughout the day.

00:13:41.320 | So don't wear your blue blockers then,

00:13:43.160 | or maybe even don't wear them at all.

00:13:44.500 | And at night, it doesn't matter

00:13:45.640 | if you have blue blockers on.

00:13:47.120 | If the lights are bright enough,

00:13:48.920 | then you're still going to be activating

00:13:51.000 | these cells and mechanisms.

00:13:52.740 | I just want to add something about the science

00:13:56.580 | behind the blue blocker confusion.

00:14:00.540 | So these melanopsin retinal cells do react to blue light.

00:14:05.260 | That is the best stimulus for one of these melanopsin cells,

00:14:08.340 | which led to the belief that blue blockers

00:14:10.520 | would be a good thing for preventing resetting

00:14:12.500 | of the circadian clock at night

00:14:13.900 | and deleterious effects of screens, et cetera.

00:14:17.000 | However, the people that made these products

00:14:20.180 | failed to actually read the papers start to finish,

00:14:23.320 | or if they did, they didn't comprehend a critical element,

00:14:26.080 | which is that most of those papers early on

00:14:28.900 | took those neurons out and put them in a dish.

00:14:31.400 | And when they did that, they divorced those neurons

00:14:34.540 | from their natural connections in the eye.

00:14:37.640 | Turns out in your eye and my eye right now,

00:14:40.380 | because that's what we care about, these cells exist.

00:14:42.980 | And these cells respond to blue light,

00:14:45.260 | but also to other wavelengths of light

00:14:47.280 | because they not only respond directly to light

00:14:49.840 | as they do in a dish,

00:14:51.020 | they also respond to input from photoreceptors.

00:14:55.360 | So if you talk to anyone in the circadian biology field,

00:14:58.460 | they'll tell you, oh yeah, this blue light thing

00:15:00.280 | has really gotten out of control

00:15:01.540 | because people assume that blue light is the culprit

00:15:04.900 | because blue light is the best stimulus.

00:15:06.620 | That doesn't mean that blue light is the only stimulus

00:15:09.080 | that will trigger these cells, okay?

00:15:10.920 | So like many things, a scientific paper can be accurate

00:15:14.200 | without being exhaustive.

00:15:15.460 | And a lot of claims about products can be accurate,

00:15:17.660 | but not exhaustive.

00:15:18.500 | So blue light during the day is great.

00:15:20.540 | Get that screen light, get that sunlight especially,

00:15:22.860 | get overhead lights.

00:15:24.680 | I talk about all this in the previous podcast.

00:15:27.020 | But at night, you really want to avoid those bright lights

00:15:30.020 | and it doesn't matter if it's blue light or something else.

00:15:32.120 | And so there was a real confusion about the papers

00:15:35.280 | and the data when most of those product recommendations

00:15:39.780 | were made.

00:15:40.620 | Okay, while we're on that topic,

00:15:44.620 | let's talk about light in other orifices of the body.

00:15:48.000 | I made a kind of a joke about this the last podcast episode,

00:15:51.020 | but a couple of people wrote to me and said,

00:15:52.740 | "Well, I've seen some claims that light delivered

00:15:55.660 | "to the ears, into the ears or the roof of the mouth

00:15:58.920 | "or up the nose can be beneficial

00:16:00.660 | "for setting circadian rhythms."

00:16:02.980 | No, not directly anyway.

00:16:07.740 | And this is a great opportunity for us to distinguish

00:16:10.080 | between what is commonly called the placebo effect,

00:16:13.160 | but a more important way to think about any manipulation,

00:16:15.980 | behavioral or otherwise that you might do

00:16:18.240 | is the difference between modulation and mediation.

00:16:22.180 | There are a lot of things that will modulate your biology.

00:16:25.940 | Putting a couple of lights up your nose,

00:16:27.800 | please don't do this, might modulate your biology

00:16:31.560 | by way of the stress hormone that's released

00:16:33.880 | when you stuff those things up your nose.

00:16:35.820 | Remember earlier, previous podcasts,

00:16:38.260 | I said that virtually anything will phase shift

00:16:40.260 | your circadian rhythm if it's different and dramatic enough.

00:16:43.260 | So the question is, is it the light delivered up the nose

00:16:47.720 | or through the ears or some other orifice

00:16:49.920 | that's mediating the process?

00:16:51.860 | Is it actually tapping into the natural biology

00:16:54.860 | of the system that you're trying to manipulate?

00:16:57.660 | And this is where I like to distinguish

00:16:58.920 | between real biology and hacks.

00:17:01.200 | I don't like the word hack or frankly neuro-hacking

00:17:04.580 | or bio-hacking, I just don't like the term

00:17:07.020 | because a hack is using something for a purpose

00:17:10.760 | for which it was not intended, right?

00:17:13.040 | But where you can kind of, it's a kind of a cheat

00:17:15.380 | and that's not how biology works well.

00:17:17.620 | So I try and distinguish between things

00:17:19.460 | that really mediate biological processes

00:17:21.580 | and things that modulate them.

00:17:23.500 | There are a number of commercial products out there

00:17:26.500 | with some studies attached to them claiming

00:17:28.380 | that light delivered to the ears or wherever

00:17:30.660 | can adjust your wakefulness or adjust your sleep.

00:17:34.740 | I've looked at those papers again,

00:17:36.820 | I'm probably going to lose some friends by saying this

00:17:38.420 | but maybe I'll gain a few as well.

00:17:40.380 | Not blue ribbon journals, frankly.

00:17:43.360 | Oftentimes read the small print,

00:17:45.500 | there was a conflict of interest clause there

00:17:47.320 | related to commercial interests.

00:17:49.160 | If somebody disagrees with me outright on this

00:17:52.000 | and can send to me a peer reviewed paper

00:17:55.360 | published in a quality journal about light delivered

00:17:57.920 | anywhere but the eyes of humans

00:18:00.200 | that can mediate circadian rhythms, wakefulness, et cetera,

00:18:03.700 | I'm more than happy to take a look at that

00:18:05.400 | and change my words and stance on this

00:18:08.560 | and do it publicly, of course.

00:18:10.420 | But until then, I'm guessing that the proper controls

00:18:14.980 | were not done of adjusting for heat that could be delivered

00:18:18.240 | which can definitely shift circadian rhythms.

00:18:19.820 | We're going to talk about temperature

00:18:20.940 | and other things like that.

00:18:22.140 | So light to the eyes folks is where these light effects

00:18:26.120 | work in humans, in other animals

00:18:28.020 | they have extraocular photoreception in humans, no.

00:18:30.740 | And just be mindful.

00:18:33.660 | I mean, I'm not trying to encourage people

00:18:34.880 | to avoid certain products in particular

00:18:37.220 | but just be mindful of this difference

00:18:38.840 | between modulation and mediation.

00:18:41.560 | And mediating a process through a hardwired

00:18:46.440 | or longstanding biological mechanism

00:18:48.360 | is really where you're going to see

00:18:49.440 | the powerful effects over time.

00:18:51.200 | I also, as you've probably noticed,

00:18:53.800 | I really tend to favor behavioral tools

00:18:55.960 | and zero cost tools first

00:18:57.840 | and getting those dialed in before you start, you know,

00:19:00.840 | plugging in and swallowing

00:19:03.040 | and, you know, putting things in various places

00:19:06.000 | just to really figure out how your biology works

00:19:08.140 | and explore that unless there's of course

00:19:10.020 | a clinical need to take a prescribed drug

00:19:12.540 | in which case by all means, listen to your doctor.

00:19:15.180 | Okay, a huge number of people asked me about

00:19:19.460 | what about light through windows?

00:19:21.680 | And I actually did an Instagram post about this.

00:19:24.160 | Look, setting your circadian clock

00:19:28.840 | with sunlight coming through a window

00:19:30.560 | is going to take 50 to 100 times longer.

00:19:32.720 | If you want the date on that,

00:19:34.520 | I'd be happy to send you to the various papers

00:19:36.920 | that were described in the previous podcast

00:19:38.800 | that Jamie Zeitzer from Stanford and I

00:19:41.360 | have discussed also elsewhere.

00:19:43.240 | But here's really the key thing with this.

00:19:45.600 | Do the experiment.

00:19:46.620 | You can download the free app Light Meter.

00:19:49.200 | You can have a bright day outside or some sunlight.

00:19:51.660 | Hold up that app, take a picture.

00:19:53.440 | It'll tell you how many lux, now you know what lux are.

00:19:56.020 | It will tell you how many lux are in that environment.

00:19:58.120 | Now close the window.

00:19:59.580 | And if you want, close the screen or don't open the screen.

00:20:01.600 | You can do all sorts of experiments

00:20:02.680 | and you'll see that it will at least half the amount of lux.

00:20:06.360 | And it doesn't scale linearly,

00:20:08.760 | meaning let's say I get a 10,000 lux outside,

00:20:13.320 | 5,000 looking out through an open window

00:20:15.400 | and then I close the window and it's 2,500 lux.

00:20:18.240 | It does not mean that you just need to view that sunlight

00:20:20.840 | for twice as long if it's half as many lux, okay?

00:20:25.480 | It's not like 2,500 lux means you need to look

00:20:28.960 | for 10 minutes and 5,000 lux means

00:20:31.960 | you look for five minutes.

00:20:33.040 | It doesn't scale that way

00:20:34.640 | just because the biology doesn't work that way.

00:20:37.000 | Best thing to do is to get outside if you can.

00:20:39.440 | If you can't, next best thing to do

00:20:40.940 | is to keep that window open.

00:20:42.560 | It is perfectly fine to wear prescription lenses

00:20:45.120 | and contacts.

00:20:46.560 | Why is it okay to wear prescription lenses and contacts

00:20:49.000 | when those are glass also,

00:20:50.840 | but looking through a window diminishes the effect?

00:20:54.860 | Well, we should think about this.

00:20:56.540 | The lenses that you wear in front of your eyes

00:20:58.800 | by prescription or on your eyes are designed

00:21:00.720 | to focus the light onto your neural retina.

00:21:03.440 | In fact, that's what nearsightedness is,

00:21:05.700 | is when the image,

00:21:06.720 | because your lens doesn't work quite right,

00:21:09.120 | the image falls in front of the neural retina,

00:21:11.300 | wearing a particular lens in front of that

00:21:14.040 | focuses the lens onto your retina, onto these very neurons

00:21:17.360 | so they can communicate that to the brain.

00:21:19.960 | Costello is loving this, he's deep in sleep.

00:21:22.960 | And if we, maybe we could play him some tones

00:21:25.060 | and he'll remember it later based on the studies

00:21:26.980 | we're going to talk about in a little bit.

00:21:30.120 | I don't know how we'd know if he remembered it or not,

00:21:32.120 | but prescription lenses are fine.

00:21:35.340 | In fact, they're great for this reason,

00:21:36.880 | they're actually focusing the light onto the retina.

00:21:39.940 | So think about this logically

00:21:41.960 | and all of a sudden it makes perfect sense.

00:21:43.520 | Your glass window or your windshield

00:21:46.120 | or the side window of your car,

00:21:48.240 | it isn't optically perfect to bring the image

00:21:53.000 | and the light onto your retina.

00:21:54.520 | In fact, what it's doing is it's scattering

00:21:56.180 | and filtering light,

00:21:57.120 | in particular the wavelengths of light that you want.

00:21:59.440 | So if you live in a low light environment,

00:22:02.880 | lots of questions about this,

00:22:04.060 | we talked about this the previous podcast,

00:22:05.760 | but just get outside for longer

00:22:08.760 | or, and or use really bright lights inside.

00:22:12.840 | Okay, so let's think about why

00:22:15.360 | I'm making some of these recommendations

00:22:17.100 | because I think it can really empower you

00:22:20.520 | with the ability to change your behavior

00:22:23.800 | in terms of light viewing and other things,

00:22:26.500 | depending on time of year,

00:22:28.240 | depending on other lifestyle factors.

00:22:32.040 | The important point to understand

00:22:33.240 | is that early in the day,

00:22:34.920 | your central circadian clocks

00:22:36.800 | and all these mechanisms are looking for a lot of light.

00:22:40.200 | I mean, they don't have a mind of their own,

00:22:41.520 | but it needs a lot of light

00:22:43.280 | to trigger this daytime signal alertness, et cetera.

00:22:46.240 | And early in the day, but not in the middle of the day,

00:22:51.240 | you can sum or add photons.

00:22:53.920 | So there's this brief period of time early in the day

00:22:56.200 | when the sun is low in the sky,

00:22:58.240 | when your brain and body are expecting

00:23:00.480 | a morning wake-up signal,

00:23:02.300 | where let's say it's not that bright outside.

00:23:04.520 | Someone sent me a picture

00:23:06.120 | or a little movie of their walk in England

00:23:08.700 | and it was pretty overcast

00:23:09.960 | and they were using light meter

00:23:11.040 | and they said it's only about 700 lux or maybe even less.

00:23:15.040 | And I said, well, stay outside longer,

00:23:17.560 | but when you get inside,

00:23:18.860 | turn on the lights really bright

00:23:20.160 | and overhead lights in particular

00:23:21.920 | because those will be best for stimulating these mechanisms.

00:23:25.800 | And that's because at least

00:23:27.060 | for the first few hours of the day,

00:23:28.520 | you can continue to sum or add photon activation

00:23:32.800 | of these cells in the eye and the brain.

00:23:35.340 | In the middle of the day, once the sun is overhead,

00:23:37.380 | or even if you stay inside all morning,

00:23:40.300 | and then you're in the circadian dead zone,

00:23:43.000 | which sounds terrible.

00:23:44.280 | And it is terrible because it doesn't matter

00:23:46.280 | if you get a ton of artificial light or even sunlight,

00:23:50.120 | you're not going to shift your circadian clock.

00:23:51.520 | You're not going to get that wake-up signal.

00:23:53.960 | And then in the evening,

00:23:55.820 | you want to think about this whole system

00:23:57.520 | as being vulnerable to even a few photons of light

00:24:00.280 | because your sensitivity to light really goes up at night.

00:24:03.280 | And I talked last time about how you can protect

00:24:05.480 | against that sensitivity by looking at the setting sun

00:24:10.200 | and watching the evening sun,

00:24:12.220 | even if it's not crossing the horizon

00:24:13.840 | around the time of sunset.

00:24:15.320 | And that's because it adjusts your retinal sensitivity

00:24:17.920 | and your melatonin pathway

00:24:19.120 | so that light is not as detrimental to melatonin at night.

00:24:22.720 | Think about the afternoon sunlight viewing

00:24:25.480 | as kind of a,

00:24:26.760 | I think of it as kind of a Netflix inoculation.

00:24:29.360 | It allows me to watch a little bit of Netflix

00:24:31.240 | in the evening.

00:24:32.740 | Although it's very hard to watch

00:24:33.640 | a little bit of anything on Netflix.

00:24:35.280 | It seems like there's some other neurobiological process

00:24:37.900 | that's going on there where I have to watch

00:24:40.000 | episode after episode after episode.

00:24:42.400 | But in any case, you can protect yourself

00:24:45.700 | against some of that bad effect of light at night

00:24:49.400 | by looking at light in the evening.

00:24:50.700 | It really does adjust down the sensitivity of the system.

00:24:54.120 | Okay, I want to talk about seasonal changes

00:24:57.480 | in all these things as they relate to mood and metabolism.

00:25:01.820 | So depending on where you are in the world,

00:25:03.720 | Northern hemisphere, Southern hemisphere,

00:25:05.300 | at the equator or closer to the poles,

00:25:07.300 | the days and nights are going to be different lengths.

00:25:10.680 | That just makes sense.

00:25:12.100 | But that translates to real biological signals

00:25:14.640 | that impact everything from wakefulness and sleep times,

00:25:18.320 | but also mood and metabolism.

00:25:21.020 | So here's how this works.

00:25:22.700 | Now, after seeing the previous episode of the podcast

00:25:25.920 | and paying attention here,

00:25:28.700 | you are armed with the knowledge to really understand

00:25:31.480 | how it is that believe it or not,

00:25:33.800 | every cell in your body is tuned

00:25:36.320 | to the movement of the planet relative to the sun.

00:25:39.820 | So as all of you know,

00:25:41.340 | the earth spins once every 24 hours on its axis.

00:25:45.080 | So part of that day we're bathed in sunlight,

00:25:47.020 | depending on where we are the other half of the day

00:25:48.820 | or part of the day we're in darkness.

00:25:50.820 | The earth also travels around the sun.

00:25:52.960 | 365 days is the time that it takes one year

00:25:57.380 | to travel around that sun.

00:25:58.840 | The earth is tilted.

00:26:02.060 | It's not perfectly upright.

00:26:05.100 | So the earth is tilted on its axis.

00:26:08.160 | So depending on where we are in that 365 day journey

00:26:11.740 | and depending on where we are in terms of hemisphere,

00:26:13.620 | Northern hemisphere, Southern hemisphere,

00:26:15.740 | some days of the year are longer than others.

00:26:19.220 | Some are very short, some are very long.

00:26:21.140 | If you're at the equator,

00:26:23.020 | you experience less variation in day length

00:26:25.060 | and therefore night length.

00:26:26.140 | And if you're closer to the poles,

00:26:27.880 | you're going to experience some very long days.

00:26:30.740 | And you're also going to experience some very short days

00:26:33.380 | depending on which pole you're at

00:26:34.860 | and what time of year it is.

00:26:36.540 | The simple way to put this is depending on time of year,

00:26:38.860 | the days are either getting shorter or getting longer.

00:26:41.180 | Now, every cell in your body adjusts its biology

00:26:45.340 | according to day length,

00:26:46.920 | except your brain, body and cells

00:26:51.140 | don't actually know anything about day length.

00:26:53.780 | It only knows night length.

00:26:55.940 | And here's how it works.

00:26:57.220 | Light inhibits melatonin powerfully.

00:26:59.900 | If days are long and getting longer,

00:27:04.700 | that means melatonin is reduced.

00:27:08.180 | The total amount of melatonin is less

00:27:11.460 | because light is more, therefore melatonin is less.

00:27:16.080 | If days are getting shorter,

00:27:18.400 | light can't inhibit melatonin as much

00:27:21.460 | through the summing of photon mechanisms

00:27:23.280 | that we talked about before.

00:27:24.960 | And that melatonin signal is getting longer.

00:27:28.800 | So every cell in your body

00:27:30.300 | actually knows external day length

00:27:32.780 | and therefore time of year

00:27:34.720 | by way of the duration of the melatonin signal.

00:27:37.820 | And in general, it's fair to say that in diurnal animals,

00:27:41.660 | meaning animals like us

00:27:42.820 | that tend to be awake during the daytime

00:27:44.780 | and nocturnal animals, which tend to be awake at night,

00:27:48.020 | the longer the melatonin signal, the more depressed,

00:27:52.660 | not necessarily clinically depressed,

00:27:54.740 | although that can happen,

00:27:55.740 | but the more depressed our systems tend to be.

00:27:58.140 | Reproduction, metabolism, mood,

00:28:04.260 | turnover rates of skin cells and hair cells

00:28:07.180 | all tend to be diminished

00:28:08.860 | compared to the spring and summer months for some,

00:28:13.780 | Northern hemisphere spring and summer months,

00:28:15.540 | or the times in which days are very long

00:28:17.880 | and there's less melatonin that tends to,

00:28:19.660 | in almost all animals, including humans,

00:28:22.600 | more breeding, more hormone elevation

00:28:25.640 | of the hormones that stimulate breeding,

00:28:27.560 | reproduction and fertility.

00:28:31.100 | Metabolism is up, lipid metabolism, fat burning is up,

00:28:36.320 | protein synthesis is up.

00:28:38.100 | These things tend to correlate with the seasons.

00:28:40.780 | Now, some people are very, very strongly tied to the seasons.

00:28:44.300 | They get depressed, clinically depressed in winter,

00:28:47.240 | and light therapies are very useful for those people.

00:28:51.540 | Some people love the winter and they're happiest in winter

00:28:53.920 | and they feel kind of depressed in summer,

00:28:55.420 | although that is far more rare.

00:28:57.620 | That doesn't mean depression cannot exist in the summer,

00:28:59.820 | but when we're talking about seasonal depression,

00:29:02.620 | that tends to be true.

00:29:04.020 | It's more depression in winter.

00:29:06.180 | Now there's other things that correlate with seasonality.

00:29:09.860 | Suicide rates tend to be highest in the spring,

00:29:12.600 | not in the winter,

00:29:13.940 | but that has to do with some of the more complicated

00:29:17.540 | and unfortunately tragic aspects of suicide,

00:29:20.120 | which is that oftentimes people will commit suicide,

00:29:22.860 | not at the very depths of their energy levels,

00:29:26.380 | but as they're emerging from those depths of low energy.

00:29:29.660 | So we'll talk about suicidality and mood disorders

00:29:32.620 | in a later podcast season, meaning a month later.

00:29:36.000 | But for now, just understand that everybody

00:29:40.220 | is going through these natural fluctuations

00:29:41.820 | depending on the duration of the melatonin signal.

00:29:44.800 | Now, this might lead you to say,

00:29:46.460 | well, then I should just really get as much light as I can

00:29:49.120 | all the time and reduce melatonin

00:29:50.900 | and feel great all the time.

00:29:51.800 | Unfortunately, it doesn't work that way

00:29:53.000 | because melatonin also has important effects

00:29:56.360 | on the immune system.

00:29:57.840 | It has important effects on transmitter systems

00:30:01.900 | in the brain, et cetera.

00:30:03.860 | So everybody needs to figure out for themselves

00:30:06.820 | how much light they need early in the day

00:30:09.920 | and how much light they need to avoid late in the day

00:30:13.100 | in order to optimize their mood and metabolism.

00:30:15.580 | There is no one-size-fits-all prescription

00:30:18.520 | because there is a range of melatonin receptors.

00:30:21.140 | There are a range of everything from metabolic types

00:30:25.420 | to genetic histories, family histories, et cetera.

00:30:29.360 | There is no one-size-fits-all prescription,

00:30:31.680 | but by understanding that light

00:30:33.700 | and extended day length inhibit melatonin

00:30:36.160 | and melatonin tends to be associated

00:30:38.320 | with a more depressed or reduced functioning

00:30:40.800 | of these kind of activity driving and mood elevating signals

00:30:45.460 | and understanding that you have some control over melatonin

00:30:48.820 | by way of light, including sunlight,

00:30:50.900 | but also artificial light.

00:30:52.340 | That should empower you, I believe,

00:30:54.200 | to make the adjustments that if you're feeling low,

00:30:57.060 | you might ask, how much light am I getting?

00:30:59.920 | When am I getting that light?

00:31:01.540 | Because sleep is also important for restoring mood, right?

00:31:04.880 | So you need sleep.

00:31:05.740 | You can't just crush melatonin across the board

00:31:09.860 | and expect to feel good

00:31:11.020 | because then you're not going to fall asleep and stay asleep.

00:31:13.960 | Melatonin not incidentally comes from,

00:31:17.880 | is synthesized from serotonin.

00:31:20.640 | Serotonin is a neurotransmitter that is associated

00:31:23.740 | with feelings of wellbeing provided to proper levels,

00:31:27.420 | but wellbeing of a particular kind,

00:31:29.420 | wellbeing associated with quiescence and calm

00:31:33.340 | and the feeling that we have enough resources

00:31:35.820 | in our immediate kind of conditions.

00:31:38.060 | It's the kind of thing that comes from a good meal

00:31:40.100 | or sitting down with friends or holding a loved one

00:31:43.180 | or conversing with somebody that you really bond with.

00:31:47.700 | Serotonin does not stimulate action.

00:31:50.700 | It tends to stimulate stillness.

00:31:53.580 | Very different than the neuromodulator dopamine,

00:31:56.260 | which is a reward feel-good neuromodulator

00:31:59.120 | that stimulates action.

00:32:00.700 | And actually dopamine is the precursor to epinephrine,

00:32:05.700 | to adrenaline, which actually puts us into action.

00:32:08.280 | It's actually made from dopamine, right?

00:32:11.420 | So you can start to think about light as a signal

00:32:15.000 | that is very powerful for modulating things

00:32:17.540 | like sleep and wakefulness,

00:32:18.620 | but also serotonin levels, melatonin levels.

00:32:22.500 | And I talked about this previously,

00:32:24.240 | but I'll mention once more

00:32:25.080 | that light in the middle of the night reduces dopamine levels

00:32:27.940 | to the point where it can start causing problems

00:32:30.480 | with learning and memory and mood.

00:32:32.640 | That's one powerful reason to avoid bright light

00:32:35.720 | in the middle of the night.

00:32:37.560 | Okay, seasonal rhythms have a number of effects,

00:32:41.380 | but humans are not purely seasonal breeders.

00:32:44.420 | Unlike a lot of animals, we breed all year long.

00:32:47.920 | In fact, there's a preponderance of September babies

00:32:52.360 | in my life, not actual babies,

00:32:54.000 | but people that are born in September,

00:32:55.180 | which means that they were conceived in December.

00:32:58.140 | Without knowing the details, we can fairly assume that.

00:33:01.120 | And December, at least in the Northern hemisphere,

00:33:04.480 | days tend to be shorter and nights tend to be longer.

00:33:08.460 | So clearly humans aren't seasonal breeders,

00:33:10.860 | but there are shifts in breeding and fertility

00:33:14.160 | that exist in humans,

00:33:15.180 | but also much more strongly in other animals.

00:33:17.660 | So seasonal effects vary.

00:33:19.260 | Some of you will experience very strong seasonal effects.

00:33:21.320 | Others of you will not.

00:33:22.980 | I think everybody should be taking care

00:33:25.520 | to get adequate sunlight and to avoid bright light at night

00:33:29.020 | throughout the year, if possible.

00:33:31.020 | Throughout this podcast and in previous episodes,

00:33:34.920 | I've been mentioning neuromodulators,

00:33:36.740 | things like serotonin and dopamine,

00:33:39.300 | which tend to bias certain brain circuits

00:33:42.340 | and things in our body to happen

00:33:43.960 | and certain brain circuits and things in our body

00:33:45.700 | not to happen.

00:33:47.300 | One of the ones I've mentioned numerous times is epinephrine,

00:33:50.000 | which is a neuromodulator that tends to put us into action,

00:33:53.000 | make us want to move.

00:33:54.520 | In fact, when it's released in high amounts

00:33:56.400 | in our brain and body, it can lead to what we call stress

00:33:59.200 | or the feeling of being stressed.

00:34:00.920 | Several people asked me,

00:34:02.840 | what's the difference between epinephrine and adrenaline?

00:34:06.320 | Adrenaline is secreted from the adrenal glands,

00:34:08.920 | which sit right above our kidneys.

00:34:10.880 | Epinephrine is the exact same molecule,

00:34:14.080 | except that it's released within the brain.

00:34:16.640 | And so people use these phrases

00:34:18.440 | or these words rather interchangeably.

00:34:20.960 | Epi means near or on top of sometimes.

00:34:24.680 | And neph, any time you see nephron or epi, it means kidney.

00:34:29.180 | So it means near the kidney.

00:34:30.280 | So epinephrine actually means near the kidney.

00:34:32.280 | So it was used originally to describe adrenaline,

00:34:35.600 | but epinephrine and adrenaline are basically the same thing.

00:34:38.400 | And they tend to stimulate agitation

00:34:40.600 | and the desire to move.

00:34:42.480 | That's what that's about.

00:34:44.480 | Which brings us to the topic of exercise.

00:34:47.560 | Got a lot of questions about exercise.

00:34:49.920 | What forms of exercise are best for sleeping well?

00:34:53.560 | When should I exercise, et cetera?

00:34:55.520 | There's a lot of individual variability around this,

00:34:59.740 | but I can talk about what I know from the science literature

00:35:04.320 | and what I happen to do myself.

00:35:06.180 | There are basically two forms of exercise

00:35:09.240 | that we can talk about.

00:35:10.080 | Although of course I realize

00:35:11.160 | there are many different forms of exercise.

00:35:13.100 | There's much more nuance to this,

00:35:14.360 | but we can talk about cardiovascular exercise

00:35:16.600 | where the idea is to repeat a movement

00:35:18.640 | over and over and over continuously.

00:35:20.140 | So that'd be like running, biking, rowing,

00:35:21.960 | the cycling, this kind of thing.

00:35:24.000 | Or there's a resistance exercise

00:35:26.940 | where you're moving, lifting,

00:35:29.360 | presumably putting down also.

00:35:31.640 | Things of progressively heavier and heavier weight

00:35:34.960 | that you couldn't do continuously for 30 minutes.

00:35:38.180 | So cardiovascular exercise

00:35:42.340 | is typically the more aerobic type exercise

00:35:44.520 | and resistance exercise of course is the more anaerobic

00:35:46.880 | type exercise.

00:35:47.720 | And yes, there's variation between the two.

00:35:50.040 | Most studies of exercise have looked at aerobic exercise

00:35:54.240 | because that's basically the thing

00:35:56.080 | that you can get a rat or a mouse to do.

00:35:58.240 | You know what's really weird about rats and mice?

00:35:59.840 | They like to run on wheels so much

00:36:02.680 | that someone actually did this study

00:36:04.080 | it was published in Science.

00:36:05.040 | They put a wheel, a running wheel in the middle of a field

00:36:08.440 | and mice ran to that wheel and ran on the wheel.

00:36:11.920 | They turns out that what they like

00:36:14.920 | is the passage of the visual image of the bars

00:36:17.700 | in front of their face.

00:36:19.140 | Which I find kind of remarkable and troubling

00:36:23.640 | 'cause it seems so like trivial.

00:36:25.400 | But anyway, they love aerobic exercise.

00:36:27.760 | And so most of the studies were done on these mice

00:36:29.620 | that love running on wheels.

00:36:30.660 | Whereas so far it's been challenging to find conditions

00:36:35.140 | in which mice really like to lift weights

00:36:37.080 | or will do it in a laboratory.

00:36:38.840 | So any weight bearing exercise studies

00:36:41.160 | really have to be done in humans.

00:36:43.000 | And since humans are what we're interested in

00:36:45.840 | there are some studies looking at these two things

00:36:50.280 | and when they tend to work best.

00:36:52.000 | Now you will see some places aerobic exercise

00:36:54.280 | is best done in the morning

00:36:55.360 | and weight training is best done in the afternoon.

00:36:57.840 | I think there's far more individual variation than that.

00:37:00.880 | I think there are however a couple of windows

00:37:04.800 | that the exercise science literature

00:37:06.600 | and the circadian literature points to

00:37:08.800 | as windows related to body temperature

00:37:11.520 | in which performance injury,

00:37:14.400 | in which performance is optimized,

00:37:17.160 | injury is reduced and so on.

00:37:20.260 | And those tend to be 30 minutes after waking.

00:37:23.780 | And that probably correlates with the inflection

00:37:26.040 | in cortisol associated with waking

00:37:27.920 | whether or not you've gotten light or not.

00:37:29.840 | Three hours after waking

00:37:31.500 | which probably correlates to the rise in body temperature

00:37:34.320 | sometime right around waking.

00:37:36.080 | And the later afternoon, usually 11 hours after waking

00:37:40.280 | which is when temperature tends to peak.

00:37:42.760 | So some people like to exercise in the morning.

00:37:45.100 | Some people like to exercise in the afternoon.

00:37:46.620 | It really depends.

00:37:48.160 | I think for those of us with very busy schedules

00:37:51.240 | it's advantageous to be able to do your training

00:37:55.840 | whenever you have the opportunity to do it

00:37:58.480 | unless you can really control your schedule.

00:38:01.500 | And so I would never want these recommendations

00:38:04.840 | to seem like recommendations

00:38:06.000 | what I'm really describing as some opportunities

00:38:07.740 | 30 minutes after waking,

00:38:09.580 | three hours after waking or 11 hours after waking

00:38:13.240 | has been shown at least in some studies

00:38:14.960 | to optimize performance, reduce injury

00:38:17.520 | and that sort of thing.

00:38:18.720 | But you really have to figure out what works for you.

00:38:21.320 | A note about working out first thing in the morning.

00:38:23.960 | Last time we talked about non-photic phase shifts.

00:38:26.400 | If you exercise first thing in the morning

00:38:29.240 | your body will start to develop an anticipatory circuit.

00:38:32.480 | There's actually plasticity in these circadian circuits

00:38:35.160 | that will lead you to want to wake up

00:38:37.640 | at the particular time that you exercise

00:38:39.400 | the previous three or four days.

00:38:41.040 | So that can be a powerful tool

00:38:42.620 | but you still want to get light exposure

00:38:44.720 | because it turns out that light and exercise converge

00:38:48.040 | to giving even bigger wake up signal to the brain and body.

00:38:52.240 | So you might want to think about that.

00:38:54.040 | Some people find if they exercise late in the day

00:38:56.280 | they have trouble sleeping.

00:38:57.920 | In general, intense exercise does that

00:39:01.880 | whereas the kind of lower intensity exercise doesn't.

00:39:05.000 | I found some interesting literature

00:39:07.020 | that talked about sleep need and exercise.

00:39:09.200 | I found this fascinating that if one is waking

00:39:14.200 | not feeling rested and recovered from

00:39:18.120 | and yet sleeping the same amount that they typically have

00:39:21.820 | it's quite possible that the intensity of exercise

00:39:24.920 | in the preceding two or three days is too high.

00:39:27.400 | Whereas if one can't recover

00:39:31.600 | no matter how much sleep they get

00:39:33.360 | they're just sleepy all the time

00:39:35.160 | I realize these things are correlated

00:39:36.800 | that the volume of training might be too high.

00:39:39.420 | Now I'm not an exercise scientist.

00:39:40.880 | We should probably get Andy Galpin or somebody else on here

00:39:43.380 | who's really an expert in this kind of stuff.

00:39:46.120 | I do realize as soon as anyone talks about exercise

00:39:48.720 | or nutrition publicly

00:39:49.800 | they're basically opening themselves up

00:39:51.800 | to all sorts of challenges

00:39:53.880 | because you can basically find support

00:39:56.040 | for almost any protocol in the literature.

00:39:59.060 | What I've looked at was two journals in particular

00:40:02.520 | International Journal of Chronobiology

00:40:04.320 | and Journal Biological Rhythms, excuse me,

00:40:08.760 | to assess these parameters

00:40:12.160 | that I've mentioned just a moment ago

00:40:14.420 | because the studies tended to be done in humans.

00:40:16.480 | They were fairly recent

00:40:17.540 | and they came from groups that I recognized

00:40:20.880 | as well as knowing that those journals are peer reviewed.

00:40:24.640 | Many of your questions were about neural plasticity

00:40:27.500 | which is the brain and nervous system's ability to change

00:40:30.400 | in response to experience.

00:40:32.900 | There was a question that asked

00:40:34.780 | whether or not these really deep biological mechanisms

00:40:37.880 | around wakefulness, time of waking, sleep, et cetera

00:40:41.360 | were subject to neural plasticity and indeed they are.

00:40:44.780 | Some of that plasticity is short-term

00:40:46.640 | and some of it is more long-term.

00:40:48.960 | There's a really good analogy here

00:40:50.280 | which is if you happen to eat on a very tight schedule

00:40:55.280 | where every day, say at 8 a.m. noon and 7 p.m.

00:41:00.080 | is when you eat your food, not suggesting you do this

00:41:02.160 | but let's say you were to do that for a couple of days.

00:41:05.440 | After a few days, you would start to anticipate

00:41:08.160 | those meal times where no matter where you were

00:41:11.040 | in the world, no matter what was going on in your life

00:41:13.760 | about five to 10 minutes before those meal times

00:41:17.040 | you would start to feel hungry and even a little agitated

00:41:19.940 | which is your body's way of trying to get you

00:41:22.440 | to forage for food.

00:41:24.040 | And that's because of some peptide signals

00:41:26.640 | that come from the periphery from your body.

00:41:29.220 | Things like hypocretinorexin that signal to the hypothalamus

00:41:33.880 | and brainstem to make you active and alert

00:41:36.060 | and look for food and feel hungry.

00:41:38.440 | So there's kind of an anticipatory circuit

00:41:41.040 | that's a chemical circuit but eventually over time

00:41:43.980 | the neurons, the neural circuits

00:41:46.240 | that control hypocretinorexin would get tuned

00:41:48.860 | to the neural circuits that are involved in eating

00:41:52.440 | and maybe even smell and taste to create a kind

00:41:56.000 | of eating circuit that's unique to your pattern,

00:41:58.920 | to your rhythms.

00:42:00.380 | The same thing is true for these waking and exercise

00:42:04.060 | and other schedules, including ultradian schedules.

00:42:06.740 | If you wake up in the morning

00:42:08.720 | and start getting your sunlight,

00:42:09.860 | you start exercising in the morning

00:42:12.160 | or you exercise in the afternoon,

00:42:14.160 | pretty soon your body will start to anticipate that

00:42:16.320 | and start to secrete hormones and other signals

00:42:19.020 | that prepare your body for the ensuing activity

00:42:22.300 | of waking up or going to sleep.

00:42:24.320 | So if you get onto a pattern or a rhythm,

00:42:28.020 | even if that rhythm isn't down to the minute,

00:42:30.860 | you'll find that there's plasticity in these circuits

00:42:33.140 | and it becomes easier to wake up early

00:42:35.000 | if that's your thing or exercise at a particular day

00:42:37.220 | if that's your thing.

00:42:38.260 | That's the beauty of neuroplasticity.

00:42:42.180 | A number of people asked,

00:42:43.320 | what can I do to increase plasticity?

00:42:45.980 | And that really comes in two forms.

00:42:48.260 | There's plasticity that we can access in sleep

00:42:51.920 | to improve rates of learning and depth of learning

00:42:56.140 | from the previous day or so.

00:42:58.040 | And there's this NSDR, non-sleep deep breaths,

00:43:01.340 | that can be done without sleeping

00:43:03.020 | to improve rates of learning

00:43:04.980 | and depth of retention, et cetera.

00:43:06.500 | So let's consider those both

00:43:08.580 | and you can incorporate these protocols if you like.

00:43:10.820 | Again, these are based on quality peer-reviewed studies.

00:43:14.640 | First, let's talk about learning in sleep.

00:43:17.260 | This is based on some work

00:43:18.400 | that I'll provide the reference for

00:43:20.900 | that was published in the journal Science.

00:43:23.660 | Excellent journal.

00:43:24.540 | Matt Walker also talks about some of these studies

00:43:27.340 | done by others in his book, "Why We Sleep."

00:43:30.860 | The studies, just to remind you,

00:43:32.620 | are structured the following way.

00:43:34.720 | An individual is brought into a laboratory,

00:43:38.260 | does a spatial memory task.

00:43:39.900 | So there tends to be a screen

00:43:42.820 | with a bunch of different objects

00:43:44.600 | popping up on the screen in different locations.

00:43:46.420 | So it might be a bulldog's face,

00:43:48.020 | there might be a cat,

00:43:48.940 | then it might be an apple,

00:43:50.060 | then it might be a pen in different locations.

00:43:52.220 | And that sounds trivially easy,

00:43:53.980 | but with time you can imagine it gets pretty tough

00:43:56.660 | to come back a day later and remember

00:43:58.660 | if something presented in a given location

00:44:01.100 | was something you've seen before

00:44:02.560 | and whether or not it was presented in that location

00:44:04.380 | or a different location.

00:44:05.340 | If you had enough objects and change the locations enough,

00:44:08.060 | this can actually be quite difficult.

00:44:10.180 | In this study, the subjects

00:44:12.460 | either just went through the experiment

00:44:15.300 | or a particular odor was released into the room

00:44:19.880 | while they were learning,

00:44:21.580 | or a tone was played in the room

00:44:23.880 | while they were learning.

00:44:25.020 | And then during the sleep of those subjects

00:44:28.840 | the following night and the following night,

00:44:31.600 | this was done repeatedly for several nights,

00:44:35.260 | the same odor or tone was played

00:44:38.900 | while the subjects were sleeping.

00:44:40.880 | They did this in different stages of sleep,

00:44:43.460 | non-REM sleep and rapid eye movement sleep, REM sleep.

00:44:46.740 | They did this with just the tone in sleep

00:44:50.520 | if the subjects had had the odor, but not the tone,

00:44:54.480 | they did it with putting the tone,

00:44:56.500 | if they had had the odor while learning.

00:44:58.260 | So basically all the controls,

00:44:59.500 | all the things you'd want to see done

00:45:01.060 | to make sure that it wasn't some indirect effect,

00:45:03.200 | some modulatory effect, okay?

00:45:05.460 | And what they found was that providing the same stimulus,

00:45:10.460 | the odor if they smelled an odor or a tone

00:45:13.540 | if the subjects heard a tone while learning,

00:45:16.500 | if they just delivered that odor or tone

00:45:19.040 | while the subjects slept,

00:45:21.020 | rates of learning and retention of information

00:45:23.520 | was significantly greater.

00:45:26.220 | This is pretty cool.

00:45:27.140 | What this means that you can cue the subconscious brain,

00:45:30.340 | the asleep brain to learn particular things

00:45:33.460 | better and faster.

00:45:35.860 | So how might you implement this?

00:45:37.180 | Well, you could play with this if you want.

00:45:39.380 | I don't see any real challenge to this provided the odor

00:45:43.060 | is a safe one and it doesn't wake you up

00:45:45.040 | and the tone is a safe one and doesn't wake you up.

00:45:49.100 | You could do this by having a metronome, for instance,

00:45:52.100 | while learning something,

00:45:53.500 | playing in the background or particular music,

00:45:55.420 | and then have that very faintly while you sleep.

00:45:58.060 | So you could apply this if you like and try this.

00:46:01.100 | There are a number of groups, I think now,

00:46:03.260 | that are trying this using tactile stimulation.

00:46:05.420 | So slight vibration on the wrist during learning

00:46:08.300 | and then the same vibration on the wrist during sleep.

00:46:10.860 | It does not appear that the sensory modality,

00:46:14.340 | whether or not it's odor or auditory tone or tactile

00:46:19.260 | stimulation, somatosensory stimulation,

00:46:21.460 | whether or not it matters.

00:46:22.820 | It's remarkable because it really shows

00:46:24.580 | that sleep is an extension of the waking state.

00:46:26.840 | We've known that for a long time,

00:46:28.320 | but this really tethers those two

00:46:30.620 | in a very meaningful and actionable way.

00:46:33.360 | So I think I'll report back to you

00:46:35.140 | as I learn more about these studies,

00:46:36.500 | but that's what I know about them at this point.

00:46:39.100 | As long as we're there, we might as well talk about dreaming

00:46:41.080 | 'cause I got so many questions about dreams.

00:46:43.420 | A couple of people want to ask me what their dreams meant.

00:46:46.180 | Look, I don't even know what my dreams mean half the time.

00:46:49.080 | I occasionally will wake up from a dream and remember it.

00:46:53.780 | If you want to remember your dreams better,

00:46:55.580 | if you're somebody who has challenges

00:46:57.700 | remembering your dreams, you can set your alarm

00:47:00.100 | so that you wake up in the middle

00:47:01.320 | of one of these 90 minute cycles,

00:47:02.860 | which toward morning tend to be occupied

00:47:04.780 | almost exclusively by REM sleep.

00:47:06.460 | Remember early in the night, you have less REM sleep

00:47:08.500 | than later in the night,

00:47:10.140 | but you want to get as much sleep as you can

00:47:12.800 | 'cause that's healthy.

00:47:13.640 | So I don't know that you want to wake yourself up.

00:47:15.900 | Some people find that writing down their thoughts

00:47:18.300 | immediately first thing in the morning

00:47:19.940 | allows them to later spontaneously remember

00:47:23.000 | their dream they had.

00:47:24.300 | There's some literature on that.

00:47:26.020 | The meaning of dreams is a little bit controversial.

00:47:28.580 | Some people believe they have strong meaning.

00:47:30.140 | Other people believe that they can be

00:47:33.380 | just spontaneous firing of neurons that were active

00:47:36.700 | in the waking state and don't have any meaning.

00:47:40.640 | There are good data to show that when you learn spatial,

00:47:43.920 | new spatial environments,

00:47:46.100 | that there's a replay of those environments,

00:47:48.780 | so-called place cells that fire in your brain

00:47:51.600 | only when you enter a particular environment,

00:47:53.560 | that those are replayed in sleep in almost direct fashion

00:47:57.100 | to the way that things were activated

00:48:00.540 | when you were learning that spatial task.

00:48:02.460 | Dreams are fascinating.

00:48:04.060 | We're paralyzed during dreams,

00:48:05.940 | which brings us to another question.

00:48:07.760 | Somebody asked about sleep paralysis.

00:48:10.820 | We are paralyzed for much of our sleep, so-called atonia.

00:48:14.340 | So presumably, so we don't act out our dreams.

00:48:16.860 | Some people wake up and they're still paralyzed.

00:48:20.400 | I've actually had this happen to me,

00:48:22.220 | not very many times, but a few times,

00:48:23.860 | and then they jolt themselves awake.

00:48:25.660 | And it actually is quite terrifying.

00:48:27.380 | I can say from personal experience to wake up,

00:48:29.540 | be wide awake and you cannot move your body at all.

00:48:33.200 | It's really quite frightening.

00:48:34.860 | There are a couple of things that will increase

00:48:36.940 | the intrusion of atonia into the wakeful state,

00:48:40.520 | which is essentially means you're waking up,

00:48:42.560 | but you can't move.

00:48:44.460 | One is marijuana, THC.

00:48:46.340 | I'm not a marijuana smoker.

00:48:48.640 | I'm not a cop or I don't know the legality where you live.

00:48:51.680 | So I'm not saying one thing or another about marijuana.

00:48:53.760 | I'm just, the fact that I had that experience

00:48:57.060 | without marijuana means that it can happen regardless.

00:49:00.320 | But marijuana smokers, for whatever reason,

00:49:02.920 | maybe it has something to do with the cannabinoid receptors

00:49:06.120 | or the serotonin receptors downstream

00:49:08.180 | of the motor pathways, I don't know.

00:49:11.480 | I couldn't find any literature on this,

00:49:13.000 | but marijuana smokers report higher frequency

00:49:16.080 | of this kind of paralysis and wakefulness

00:49:19.520 | as you transition from sleep to wakefulness.

00:49:21.900 | I suppose probably one could learn

00:49:23.520 | to get comfortable with it.

00:49:24.680 | For me, it was terrifying

00:49:26.160 | 'cause I'm just used to being able

00:49:27.340 | to move my limbs fortunately, and I wasn't able to.

00:49:30.340 | And it's quite a thing, let me tell you.

00:49:36.240 | Okay, some other questions about neuroplasticity.

00:49:39.740 | So the other form of neuroplasticity

00:49:42.740 | is not the neuroplasticity that you're amplifying

00:49:45.900 | by listening to tones or smelling odors in sleep,

00:49:50.460 | but the neuroplasticity that you can access

00:49:52.140 | with non-sleep deep rest.

00:49:54.160 | So NSDR, non-sleep deep rest,

00:49:57.180 | as well as short 20-minute naps,

00:49:59.360 | which are very close to non-sleep deep rest

00:50:01.500 | because people rarely drop into deep states of sleep

00:50:04.180 | during short naps unless they're very sleep deprived.

00:50:07.020 | NSDR has been shown to increase rates of learning

00:50:12.900 | when done for 20-minute bouts

00:50:14.940 | to match an approximately 90-minute bout of learning.

00:50:20.420 | So what am I talking about?

00:50:21.680 | 90-minute cycles are these ultradian cycles

00:50:24.760 | that I've talked about previously.

00:50:26.380 | And we tend to learn very well by taking a 90-minute cycle,

00:50:30.500 | transitioning into some focus mode early in the cycle

00:50:33.500 | when it's hard to focus and then deep focus

00:50:35.660 | and learning feels almost like agitation and strain.

00:50:39.300 | And then by the end of that 90-minute cycle,

00:50:41.500 | it becomes very hard to maintain focus

00:50:44.700 | and learn more information.

00:50:46.660 | There's a study published in Cell Reports last year,

00:50:48.980 | great journal, excellent paper,

00:50:51.900 | showing that 20-minute naps or light sleep

00:50:56.260 | of the sort of non-sleep deep rest

00:50:58.000 | taken immediately after or close to,

00:51:01.080 | it doesn't have to be immediately

00:51:02.220 | after you finished the last sentence of learning

00:51:04.120 | or whatever it is or bar of music.

00:51:07.080 | But a couple of minutes after transitioning

00:51:09.180 | to a period of non-sleep deep rest

00:51:11.920 | where you're turning off the analysis of duration path

00:51:14.740 | and outcome has been shown to accelerate learning

00:51:17.400 | to a significant degree,

00:51:19.020 | both the amount of information

00:51:20.720 | and the retention of that information.

00:51:22.680 | So that's pretty cool because this is a cost-free,

00:51:27.680 | drug-free way of accelerating learning

00:51:30.420 | without having to get more sleep,

00:51:32.560 | but simply by introducing these 20-minute bouts.

00:51:35.660 | I would encourage people if they want to try this

00:51:37.700 | to consider the 20 minutes per every 90 minutes

00:51:41.220 | of ultradian learning cycle.

00:51:42.860 | There you're incorporating

00:51:43.740 | a number of different neuroscience-backed tools,

00:51:47.380 | 90-minute cycles for focused learning,

00:51:50.060 | it could be motor, it could be cognitive,

00:51:51.580 | it could be musical, whatever,

00:51:53.260 | and then transition to a 20-minute

00:51:56.120 | non-sleep deep rest protocol.

00:51:58.300 | I just want to cue you the fact that in last episode

00:52:00.480 | in the caption on YouTube,

00:52:02.020 | we provided links to two different

00:52:04.280 | yoga nidra non-sleep deep rest protocols

00:52:06.400 | as well as hypnosis protocols that are clinically backed

00:52:08.840 | from my colleague David Spiegel

00:52:10.620 | at Stanford Psychiatry Department.

00:52:14.460 | All those resources are free.

00:52:16.500 | There are also a lot of other hypnosis scripts out there.

00:52:20.500 | I like the ones from Michael Sealy, S-E-A-L.

00:52:23.800 | I think it's E-Y, although maybe it's just L-Y.

00:52:26.260 | You can find them easily on YouTube.

00:52:28.060 | Clinical hypnosis scripts, meaning not staged hypnosis.

00:52:31.260 | They're not designed to get you to do anything.

00:52:33.580 | In fact, they're just designed

00:52:34.960 | to help rewire your brain circuitry.

00:52:37.280 | Now, how does hypnosis work that way?

00:52:39.580 | This has a lot to do with sleep

00:52:40.820 | because it engages neuroplasticity by bringing together

00:52:43.940 | two things that normally are separate from one another.

00:52:46.360 | One is the alert focused wakeful state

00:52:49.200 | where you activate the learning.

00:52:50.740 | And then there's the deep rest

00:52:52.460 | where the actual reconfiguration

00:52:54.580 | of the neurons and synapses takes place.

00:52:57.140 | Hypnosis brings both the focus and the deep rest component

00:53:01.300 | into the same compartment of time.

00:53:03.980 | It's a very unique state in that way.

00:53:05.940 | So hypnosis kind of maximizes the learning bout

00:53:10.020 | and the non-sleep deep rest bout and combines them.

00:53:13.020 | But of course, that requires some guidance from a script

00:53:16.700 | or from a hypnotist, clinically trained hypnotist,

00:53:20.020 | and it becomes hard to acquire detailed information.

00:53:23.000 | It's more about shifts in state like fear to states of calm

00:53:27.960 | or smoking to quitting smoking, anxiety around a trauma

00:53:32.960 | to release of anxiety around a trauma

00:53:36.620 | rather than specific information learned in hypnosis, okay?

00:53:40.420 | So hypnosis seems more about modulating the circuits

00:53:43.020 | that underlie state as opposed to specific information.

00:53:46.440 | Although I would not be surprised

00:53:48.680 | if there weren't certain forms of hypnosis

00:53:50.300 | that could increase retention and learning

00:53:52.520 | of specific information,

00:53:53.500 | but I'm not aware of any of those protocols out there yet.

00:53:57.540 | Which brings us to the next thing

00:53:59.060 | about learning and plasticity,

00:54:00.940 | which is nootropics, AKA smart drugs.

00:54:04.000 | This is a big topic.

00:54:07.080 | That sigh was a sigh of concern

00:54:10.060 | about how to address nootropics in a thorough enough

00:54:14.060 | but thoughtful enough way.

00:54:15.940 | Look, I have a lot of thoughts about nootropics.

00:54:19.100 | First of all, it means smart drugs, I believe.

00:54:22.640 | And I don't like that phrase

00:54:23.940 | because let's just take a step back

00:54:25.840 | and think about exercise.

00:54:28.360 | You just say, I want to be more physically fit.

00:54:31.160 | What does that mean?

00:54:32.200 | Does it mean, I would ask for more specificity.

00:54:34.400 | I'd say, do you want to be stronger?

00:54:36.440 | Okay, maybe you need to lift heavier objects progressively.

00:54:39.320 | Do you want more endurance?

00:54:41.260 | Very different protocol to access endurance.

00:54:43.200 | Do you want flexibility?

00:54:44.340 | Do you want explosiveness or suppleness?

00:54:46.880 | Huge range of things that we call physical fitness.

00:54:49.640 | Maybe you want all of those.

00:54:51.660 | If we were talking about emotional fitness,

00:54:54.740 | we would say, well, an ability to feel empathy,

00:54:58.320 | but probably also to disengage from empathy

00:55:00.460 | because you don't want to be tethered

00:55:01.500 | to other people's emotions all the time.

00:55:02.980 | That's not healthy either.

00:55:04.960 | You would think about being able

00:55:07.060 | to access a range of emotions,

00:55:09.120 | but for some people,

00:55:10.780 | their range into the sadness regime is really quite vast,

00:55:14.580 | but their range into the happiness regime

00:55:16.320 | might be kind of limited.

00:55:17.280 | For other people who are in a manic state,

00:55:19.240 | it might be they can access all the happy stuff,

00:55:21.200 | but not the sadder stuff.

00:55:22.940 | So I'm speaking by way of analogy here,

00:55:27.320 | but if we say, we're talking about cognitive abilities,

00:55:31.320 | we have to ask, okay, creativity, memory.

00:55:37.980 | We tend to associate intelligence with memory.

00:55:40.940 | I think this goes back to like spelling bees or something,

00:55:43.340 | the ability to retain a lot of information.

00:55:46.400 | And just regurgitate information,

00:55:48.460 | which will get you some distance in some disciplines of life

00:55:51.620 | but it won't allow you creative thinking.

00:55:53.460 | It's necessary for creative thinking.

00:55:55.640 | You need a knowledge base, right?

00:55:57.780 | You can't just look up everything on Google,

00:55:59.600 | despite what certain educators or so-called educators say.

00:56:03.800 | You need a database so that you have the raw materials

00:56:07.220 | with which to be creative.

00:56:08.380 | So necessary to have memory,

00:56:10.620 | but not sufficient to be creative, right?

00:56:13.020 | The creative could have a poor memory for certain things,

00:56:16.260 | but certainly not for everything.

00:56:17.740 | They can't have anterograde and retrograde amnesia.

00:56:20.300 | They'd be like the goldfish that every time around the tank,

00:56:23.620 | it can't remember where it's at.

00:56:25.660 | I actually don't know that they've ever done

00:56:27.100 | that experiment by the way,

00:56:29.060 | so no disrespect to goldfish, but you know.

00:56:32.240 | So you get the idea, you've got creativity,

00:56:34.380 | you have memory, you have the ability to task switch, right?

00:56:37.780 | You have the ability to strategy develop

00:56:41.860 | and strategy implement.

00:56:43.020 | So the problem I have with the concept of a nootropic

00:56:45.860 | or a smart drug is it's not specific

00:56:47.720 | as to what cognitive algorithm you're trying to engage.

00:56:52.660 | We need more specificity.

00:56:54.540 | That said, there are elements to learning

00:56:57.120 | that we've discussed here before that are very concrete.

00:57:00.380 | Things like the ability to focus

00:57:02.780 | and put the blinders on to everything else

00:57:04.820 | that's happening around you and in your head mainly, right?

00:57:08.660 | Distractions about things you should be doing,

00:57:10.400 | could be doing or might be doing

00:57:12.280 | and focus on what you need to do.

00:57:14.140 | And then that's required for triggering

00:57:16.660 | the acetylcholine neuromodulator

00:57:18.820 | that will then allow you to highlight

00:57:21.780 | the particular synapses that will then later change in sleep.

00:57:24.840 | So no nootropic allows you to bypass the need

00:57:27.840 | for sleep and deep rest.

00:57:29.860 | That's important to understand.

00:57:31.280 | So I daydream about a day when people will be able

00:57:38.740 | to access compounds that are safe,

00:57:42.220 | that will allow them to learn better,

00:57:43.760 | meaning to access information, focus better,

00:57:47.240 | as well as to sleep better and activate the plasticity

00:57:50.340 | from the learning bout.

00:57:51.940 | Right now, most nootropics tend to bundle

00:57:54.240 | a bunch of things together.

00:57:55.400 | Most of them include some form of stimulant, caffeine.

00:57:59.580 | Episode two, I tell you more probably

00:58:01.740 | than you ever wanted to know about caffeine adenosine

00:58:03.820 | and how that works.

00:58:04.660 | So refer there for how caffeine works.

00:58:07.600 | But stimulants will allow you to increase focus

00:58:10.760 | up to a particular point.

00:58:12.520 | If you have too little alertness in your system,

00:58:15.320 | you can't focus too much.

00:58:16.640 | However, you start to cliff and focus drifts, okay?

00:58:19.400 | So you can't just ingest more stimulant to be more focused.

00:58:23.100 | It doesn't work that way.

00:58:24.540 | Most nootropics also include things that increase

00:58:28.000 | or are designed to increase acetylcholine,

00:58:30.400 | things like alpha-GPC and other things of that sort.

00:58:34.060 | And indeed there's some evidence

00:58:35.820 | that they can increase acetylcholine.

00:58:37.240 | I refer you again to examine.com, the website,

00:58:40.120 | to evaluate any supplements or compounds for their safety

00:58:43.300 | and their effects in humans and animals.

00:58:45.340 | Free website, as well as with links to studies.

00:58:49.900 | So we need the focus component.

00:58:51.740 | We need the alertness component.

00:58:52.980 | The alertness component comes from epinephrine,

00:58:54.820 | traditionally from caffeine stimulation.

00:58:57.260 | The acetylcholine stimulation traditionally comes

00:59:00.100 | from choline donors or alpha-GPC, things of that sort.

00:59:03.820 | And then you would want to have some sort of off switch

00:59:07.020 | because anything that's going to really stimulate

00:59:09.880 | your alertness that then provides a crash,

00:59:12.360 | that crash is not a crash into the deep kind

00:59:14.880 | of restful slumber that you would want for learning.

00:59:18.520 | It's a crash into the kind of,

00:59:20.520 | let's just call it lopsided sleep, meaning it's deep sleep,

00:59:26.840 | but it lacks certain spindles and other elements

00:59:29.320 | of the physiology, sleep spindles,

00:59:31.180 | that really engage the learning process

00:59:33.700 | and the reconfiguration of synapses.

00:59:35.880 | So right now, my stance on nootropics is that maybe,

00:59:40.880 | maybe for occasional use, provided it's safe for you,

00:59:45.600 | I'm not recommending it, but in general,

00:59:48.480 | it tends to use more of a shotgun approach

00:59:51.560 | than is probably going to be useful

00:59:54.000 | for learning and memory in the long run.

00:59:56.900 | A lot of people ask about modafinil or armodafinil,

00:59:59.620 | which was designed for treatment of narcolepsy.

01:00:01.540 | So right there, it tells you it's a stimulant.

01:00:03.440 | And yes, there is evidence

01:00:04.560 | it will improve learning and memory.

01:00:05.860 | Modafinil is very expensive.

01:00:07.340 | Last time I checked, armodafinil, I think,

01:00:09.120 | is the recent released generic version of this

01:00:12.880 | that's far less expensive.

01:00:14.920 | Most of these things look a lot like amphetamine,

01:00:17.040 | and many of them have the potential for addiction

01:00:21.380 | or can be habit forming, but more importantly,

01:00:25.200 | a lot of those things also can create metabolic effects

01:00:28.160 | by disruption to insulin receptors and so forth.

01:00:30.480 | So you want to approach those with a strong sense of caution.

01:00:34.720 | Now, there are the milder things that act as nootropics.

01:00:38.240 | I mentioned some of them, like alpha-GPC.

01:00:40.420 | Some people like ginkgo.

01:00:42.760 | Ginkgo gives me vicious headaches, so I don't take it.

01:00:45.720 | So people really differ.

01:00:47.680 | Last podcast, I recommended magnesium threonate

01:00:52.080 | if you were exploring supplements.

01:00:53.960 | I'm not recommending anything directly.

01:00:55.600 | I'm just saying if you're exploring supplements,

01:00:57.580 | magnesium threonate seems among the magnesiums

01:01:00.980 | to be one of the more bioavailable and useful for sleep.

01:01:05.200 | I recommend it actually to a good friend of mine.

01:01:07.500 | It gave him, at very low dose,

01:01:09.580 | he had stomach issues with it.

01:01:11.300 | He just had to simply stop taking it.

01:01:12.820 | So there's variability there.

01:01:14.200 | It gave him some stomach cramping

01:01:16.340 | and just didn't feel good on it.

01:01:17.800 | Stopped it, he felt better.

01:01:19.540 | Other people take magnesium threonate and feel great.

01:01:22.580 | I was asked, do magnesium need to be taken

01:01:25.000 | with or without food, daytime or before sleep?

01:01:27.180 | If you're going to go that route,

01:01:29.080 | it should be taken 30 to 60 minutes before sleep

01:01:31.340 | 'cause it's designed to make you sleepy.

01:01:33.040 | And I'm not aware that it has to be taken with food,

01:01:36.420 | but again, all of this has to be run by your doctor

01:01:38.480 | and this is your healthcare to govern.

01:01:42.200 | These are not strict recommendations, so look into it.

01:01:44.800 | But magnesium threonate,

01:01:47.640 | most people I've recommended it to

01:01:50.180 | have benefit from it tremendously.

01:01:52.160 | Some people can't tolerate it, so you have to find out.

01:01:55.240 | There were a number of questions about other supplements

01:01:57.280 | designed to access deep sleep

01:01:59.660 | in part to access neuroplasticity,

01:02:01.800 | but now I'm just sort of transitioning

01:02:03.440 | from neuroplasticity to these compounds

01:02:06.180 | that can regulate sleep.

01:02:07.120 | One of them that I discussed at the end of the last podcast,

01:02:09.240 | I got a lot of questions about, is apigenin,

01:02:11.240 | A-P-I-G-E-N-I-N.

01:02:14.000 | Apigenin, if you look in the literature,

01:02:16.760 | the way it works is it increases some of the enzymes

01:02:19.260 | associated with GABA metabolism.

01:02:21.100 | It actually, GABA is an inhibitory neurotransmitter.

01:02:24.640 | It's the neurotransmitter that is increased

01:02:27.280 | after a couple drinks containing alcohol

01:02:30.960 | and that shut down the forebrain.

01:02:32.700 | Apigenin is a derivative of the chamomile.

01:02:37.500 | I think the proper pronunciation of this

01:02:39.600 | is matricaria chamomila,

01:02:41.640 | although I always feel like I should be using

01:02:42.880 | a Spanish accent whenever I say something like that.

01:02:47.080 | Other related things that impact the GABA system

01:02:49.320 | and increase GABA are things like passion flower,

01:02:51.880 | which is passiflora incurata.

01:02:55.040 | I don't know why the Italian, is that Italian?

01:02:57.280 | Anyway, my Italian colleagues, please forgive me.

01:03:00.120 | I have some very close Italian friends

01:03:02.500 | and colleagues in Genoa.

01:03:03.820 | I butchered the Italian, sorry.

01:03:06.600 | In any event, apigenin and passion flower

01:03:10.300 | found in a lot of supplements

01:03:14.400 | designed to increase sleepiness and sleep

01:03:16.560 | and they work presumably because they increase GABA.

01:03:18.800 | Actually, they work on chloride channels

01:03:21.060 | rather than give you a whole lecture

01:03:22.360 | on membrane biophysics and neurons.

01:03:24.800 | I'll just say that when neurons are really active,

01:03:27.200 | it's because sodium ions, salt, rushes into the cells

01:03:31.740 | and causes them to fire electrically.

01:03:33.680 | The cells tend to become less active as more chloride,

01:03:36.680 | which is a negatively charged ion.

01:03:38.860 | This is probably taking some of you back

01:03:41.240 | to either the wonderful times or traumas

01:03:44.840 | of high school physics.

01:03:46.280 | The chloride is negatively charged

01:03:48.040 | so it tends to make cells less electrically positive

01:03:51.380 | 'cause it carries a negative charge

01:03:53.080 | and hyperpolarizes the neuron.

01:03:55.460 | So apigenin works through these,

01:03:57.580 | increasing the activity of these chloride channels.

01:03:59.960 | Passion flower works by increasing the activity

01:04:02.100 | of these chloride channels and GABA transmission.

01:04:04.500 | It tends to increase this inhibitory neurotransmitter

01:04:07.340 | that shuts off our thinking,

01:04:09.480 | our analysis of duration, path, and outcome.

01:04:11.740 | So if you're going to explore these things,

01:04:14.220 | I suggest you at least know how they work.

01:04:16.340 | You at least go to examine.com

01:04:19.300 | that you talk to your doctor about them.

01:04:21.340 | Some people asked about serotonin

01:04:23.740 | for getting to sleep and staying asleep.

01:04:26.820 | Now, I understand the rationale here.

01:04:29.580 | Just like I understand the rationale

01:04:30.980 | of taking something like mucuna purines or L-DOPA

01:04:33.660 | to increase dopamine,

01:04:34.880 | but sometimes what works on paper

01:04:36.780 | doesn't really work in the real world.

01:04:38.920 | I personally have tried taking a supplement

01:04:41.100 | which was L-Tryptophan,

01:04:42.860 | which is the precursor to serotonin or 5-HTP,

01:04:46.460 | which is designed to increase,

01:04:48.040 | it is serotonin basically.

01:04:49.620 | You're just one biochemical step away

01:04:52.380 | from taking actual serotonin.

01:04:55.100 | And I'll be honest,

01:04:56.180 | the sleep that I had with increased serotonin

01:04:58.940 | by way of tryptophan or 5-HTP was dreadful.

01:05:01.740 | I fell asleep almost immediately.

01:05:03.620 | You say, well, that's great.

01:05:04.620 | And 90 minutes later I woke up

01:05:06.220 | and I couldn't sleep almost for 48 hours.

01:05:08.420 | Now that was me.

01:05:09.260 | I have a pretty sensitive system to certain things

01:05:11.180 | and not to other things.

01:05:12.220 | Some people love these things.

01:05:13.500 | So you really have to be thoughtful

01:05:15.340 | and explore them with that kind of awareness

01:05:18.460 | of being thoughtful

01:05:20.140 | and realizing that what works for you

01:05:22.040 | might not work for everybody

01:05:23.060 | and what works for everybody might not work for you.

01:05:25.780 | Okay, I'd like to continue

01:05:27.020 | by talking about the role of temperature in sleep,

01:05:30.740 | accessing sleep, staying asleep and wakefulness.

01:05:34.940 | But first I want to tell a joke

01:05:38.340 | because I think this joke really captures

01:05:40.380 | some of the critical things to understand

01:05:42.620 | about any self-experimentation that you might do.

01:05:46.160 | So this is a story that was told to me

01:05:48.220 | by a colleague of mine who's now a professor of Caltech,

01:05:51.140 | not to be named.

01:05:52.220 | So there's a scientist and they're in their lab

01:05:57.080 | and they're trying to understand

01:05:59.020 | how the nervous system works.

01:06:01.100 | So they go over to a tank and they pick up a frog

01:06:03.860 | and they take the frog

01:06:06.500 | and they put it down on the table and they clap.

01:06:09.040 | [claps]

01:06:10.400 | And the frog jumps.

01:06:11.440 | So they think for a while, they pick up the frog, okay.

01:06:16.320 | They go over to the cabinet

01:06:18.160 | and they take out a little bit of a paralytic drug

01:06:22.520 | and they inject it locally into the back leg,

01:06:26.240 | set it down and clap.

01:06:28.220 | [claps]

01:06:29.440 | And the frog jumps,

01:06:30.880 | but it kind of like jumps to the side a little bit.

01:06:33.760 | And they pick it up.

01:06:35.440 | They inject the paralytic into the other back leg.

01:06:38.520 | They clap again.

01:06:40.200 | The frog jumps, but it really doesn't jump well that time.

01:06:42.960 | It kind of drags itself forward.

01:06:45.320 | So they pick it up and they inject the paralytic

01:06:47.100 | into the remaining two legs.

01:06:49.320 | They set it down and they clap.

01:06:51.440 | The frog doesn't jump.

01:06:54.640 | They go, "Oh my goodness, the legs are used for hearing."

01:06:58.800 | Now they publish the paper.

01:07:02.280 | Paper comes out in a great journal, news releases.

01:07:05.520 | It's a really big deal.

01:07:06.520 | Their career takes off.

01:07:08.440 | 20 years later, a really smart graduate student comes along

01:07:12.240 | and says, "Yeah, but that's loss of function."

01:07:15.360 | Doesn't really show gain of function.

01:07:17.380 | So let's take a closer look.

01:07:18.820 | So they repeat the first experiment and it checks out.

01:07:22.800 | Everything happens the same way.

01:07:24.400 | But then they take the frog

01:07:26.640 | and they inject a drug into all four legs

01:07:30.680 | that turns off the paralytic, right?

01:07:34.160 | It's an antagonist.

01:07:35.560 | They set the frog down.

01:07:37.580 | They clap and the frog jumps.

01:07:40.240 | They go, "Oh my goodness, it's true.

01:07:42.180 | The legs really are for hearing."

01:07:45.180 | Now, first of all, I want to make the point

01:07:47.780 | that this is not to illustrate

01:07:50.280 | that science is not a good practice.

01:07:52.080 | It is.

01:07:52.920 | We need to do loss of function

01:07:54.480 | and gain in function experiments.

01:07:56.720 | But just to show that correlation

01:07:58.360 | and causation is complicated,

01:08:00.220 | you need to do a variety of control experiments

01:08:02.440 | and you really need to figure out what works for you.

01:08:04.800 | And so while science can provide answers

01:08:07.640 | about what works under very controlled conditions,

01:08:10.200 | it doesn't and can never address all the situations

01:08:14.100 | in which a given compound,

01:08:15.620 | a given practice will or won't work.

01:08:17.780 | And it's not just individual variability,

01:08:19.360 | it's that there are a number of different factors.

01:08:21.120 | You all, of course, know that light can activate

01:08:23.940 | and shift your circadian rhythm,

01:08:25.120 | but so can exercise, so can food.

01:08:27.260 | The last point I want to make is an important one,

01:08:28.940 | which is that no frogs were hurt

01:08:32.020 | in the telling of this joke.

01:08:33.980 | Okay, so let's continue.

01:08:35.640 | I want to talk about temperature.

01:08:37.380 | Temperature is super interesting

01:08:39.140 | as it relates to circadian rhythms

01:08:41.520 | and wakefulness and sleep.

01:08:43.260 | First, let's take a look at what's happening

01:08:46.580 | to our body temperature across each 24-hour cycle.

01:08:51.580 | In general, our temperature tends to be lowest

01:08:54.780 | right around 4 a.m. and starts creeping up

01:08:58.660 | around 6 a.m., 8 a.m., and peaks sometime

01:09:02.220 | between 4 p.m. and 6 p.m.

01:09:05.200 | Now, that varies from person to person,

01:09:07.260 | but in general, if we were to continuously monitor

01:09:09.980 | or occasionally monitor temperature,

01:09:11.180 | that's what we would see.

01:09:12.940 | Now, what's interesting is that even in the absence

01:09:14.940 | of any light cues or meal cues, we would have a shift.

01:09:19.580 | We would have an oscillation or a rhythm in our temperature

01:09:22.080 | that would go from high to low.

01:09:24.460 | This is why the idea that we're all 96.8

01:09:26.660 | and that's our correct temperature, forget that.

01:09:28.620 | That is no longer true.

01:09:30.500 | It never was true.

01:09:31.580 | It depends on what time of day you measure temperature.

01:09:34.220 | However, there is a range which is within normal range.

01:09:37.320 | I think most of us associate fever

01:09:38.940 | with somewhere around 100, 101, 103.

01:09:41.480 | That's concerning, and we will be very concerned

01:09:43.940 | if temperature dropped too low as well.

01:09:46.580 | The way that the temperature rhythm that's endogenous,

01:09:50.140 | that's within us and rhythmic no matter what,

01:09:52.700 | the way it gets anchored to the pattern I described before

01:09:57.100 | of being lowest at 4 a.m. and increasing again

01:09:59.480 | around through the day until about 4 to 6 p.m.

01:10:03.620 | is by way of entrainment or matching to some external cue,

01:10:08.620 | which is almost always going to be light, but also exercise.

01:10:13.320 | Now, you may have experienced this temperature rhythm

01:10:17.100 | and how quickly it can become unentrained

01:10:20.820 | or it can fall out of entrainment.

01:10:23.540 | Here's an experiment I wouldn't want you to do,

01:10:25.900 | but you've probably experienced this before,

01:10:28.120 | where you wake up, it's sunny outside,

01:10:31.420 | and maybe you have some email or some things to take care of,

01:10:33.780 | or maybe you didn't sleep that well the night before,

01:10:35.400 | and so you stay indoors.

01:10:37.660 | You don't change anything about your breakfast.

01:10:39.340 | You don't change anything about your within-home temperature

01:10:42.620 | or anything like that.

01:10:43.940 | And somewhere right around 10 or 11 o'clock,

01:10:45.900 | you start feeling kind of chilled, like you're cold.

01:10:48.880 | Well, what happened was the oscillators,

01:10:51.620 | the clocks in your various tissues

01:10:53.380 | that are governed by temperature and circadian rhythm

01:10:56.100 | are starting to split away

01:10:58.680 | from your central clock mechanisms.

01:11:00.880 | So it's actually important

01:11:02.300 | that your temperature match day length.

01:11:04.740 | Now, there's another way in which temperature matches,

01:11:06.840 | or daytime, excuse me.

01:11:08.440 | There's also an important way

01:11:09.860 | in which temperature matches day length.

01:11:11.520 | In general, as days get longer, it tends to be hotter out.

01:11:15.560 | Not always, but in general, that's the way it is.

01:11:18.320 | And as days get shorter, it tends to be colder outside.

01:11:21.740 | So temperature and day length are also linked,

01:11:25.440 | metabolically they're linked,

01:11:26.820 | biologically they're linked, excuse me,

01:11:29.780 | and atmospherically they're linked,

01:11:31.320 | for the reasons that we talked about before

01:11:32.660 | about duration of day length

01:11:34.980 | and other climate features and so forth.

01:11:37.440 | So one of the most powerful things

01:11:39.460 | about setting your circadian rhythm properly

01:11:41.780 | is that your temperature will start to fall

01:11:44.200 | into a regular rhythm.

01:11:45.400 | And that temperature has a very strong effect

01:11:48.420 | on things like metabolism

01:11:50.440 | and when you will feel most willing

01:11:53.100 | and interested in exercising.

01:11:55.420 | Typically, the willingness to exercise and engage

01:11:58.160 | in any kind of activity, mental or physical,

01:12:00.240 | is going to be when that rise in temperature is steepest,

01:12:03.600 | when the slope of that line is greatest,

01:12:05.220 | that's why 30 minutes after waking

01:12:07.040 | is one of those key windows,

01:12:08.300 | as well as three hours after waking,

01:12:10.040 | and then when temperature actually peaks,

01:12:12.340 | which is generally, generally about 11 hours after waking.

01:12:17.340 | So this is why we say that temperature

01:12:20.580 | and circadian rhythm are linked,

01:12:22.380 | but they're actually even more linked than that.

01:12:25.320 | We've talked before about how light enters the eye,

01:12:27.900 | triggers activation of these melanopsin cells,

01:12:30.120 | which then triggers activation of the suprachiasmatic nucleus

01:12:32.920 | the master circadian clock.

01:12:34.660 | And then I always say the master circadian clock

01:12:36.620 | informs all the cells and tissues of your body

01:12:38.860 | and puts them into a nice cohesive rhythm.

01:12:41.780 | But what I've never answered

01:12:44.080 | was how it actually puts them into that rhythm.

01:12:46.660 | And it does it two ways.

01:12:48.380 | One is it secretes a peptide.

01:12:50.180 | A peptide is just a little protein

01:12:51.480 | that floats through the bloodstream

01:12:53.400 | and signals to the cells,

01:12:54.660 | okay, we're tuning your clock

01:12:55.820 | kind of like a little, you know, in a watch store,

01:12:57.760 | the watch store owner would tune the clocks.

01:13:00.300 | But the other way is it synchronizes the temperature

01:13:03.680 | under which those cells exist.

01:13:05.820 | So temperature is actually the effector

01:13:08.720 | of the circadian rhythm.

01:13:10.660 | Now, this is really important

01:13:12.200 | because changes in temperature by way of exercise,

01:13:15.620 | by way of eating, but especially by way of exercise

01:13:18.740 | can start to shift our circadian rhythm pretty dramatically.

01:13:22.220 | But let's even go to a more extreme example.

01:13:24.920 | Nowadays, there's some interest in cold showers

01:13:28.160 | and ice baths.

01:13:29.240 | Not everybody is doing this, I realize.

01:13:30.880 | People seem to either love this or hate this.

01:13:33.200 | I don't mind the cold dunk thing.

01:13:35.480 | I get regular about this from time to time and I'll do it.

01:13:38.280 | I haven't been doing it recently.

01:13:39.880 | It's always painful to do the first couple of times

01:13:41.760 | and then you get kind of used to it.

01:13:43.280 | However, I've taken people to a cold dunk or an ice bath.

01:13:45.960 | I have a family member who wouldn't get in literally

01:13:48.740 | past her toes.

01:13:49.860 | She was like, this is just too aversive for me.

01:13:51.940 | Some people really liked the cold.

01:13:53.180 | People very tremendously.

01:13:54.660 | Getting into an ice bath is very interesting

01:13:57.840 | because you have a rebound increase in thermogenesis.

01:14:01.520 | Now you should know from the previous episode

01:14:03.720 | that as that temperature increases,

01:14:06.020 | it will shift your circadian rhythm

01:14:07.980 | and which direction it shifts your circadian rhythm

01:14:10.140 | will depend on whether or not you're doing it

01:14:11.360 | during the daytime or late in the day.

01:14:12.780 | If you do it after 8 p.m., it's going to make your day

01:14:15.840 | longer, right?

01:14:17.720 | Because your body and your central clocks

01:14:21.320 | are used to temperature going up early in the day

01:14:24.640 | and throughout the day and peaking in the afternoon.

01:14:26.780 | If you then increase that further

01:14:29.100 | or you simply increase it over its baseline at 8 p.m.

01:14:32.080 | after temperature was already falling,

01:14:34.220 | even if it's just by a half a degree or a couple of degrees

01:14:36.560 | or you do that with exercise,

01:14:37.800 | doesn't have to be with the ice bath,

01:14:39.360 | you are extending, you are shifting forward,

01:14:41.800 | you're phase delaying your clock,

01:14:44.280 | you're convincing your clock

01:14:45.920 | and therefore the rest of your body

01:14:47.320 | that the day is still going, right?

01:14:49.520 | You're giving it the perception,

01:14:50.960 | the cellular and physiological perception

01:14:53.820 | that the day is getting longer

01:14:54.960 | and you will want to naturally stay up later

01:14:57.560 | and wake up later.

01:14:59.220 | Now you might say, wait, I do an ice bath late at night

01:15:01.680 | and I feel great and I fall deeply asleep.

01:15:04.300 | Well, cold can trigger the release of melatonin.

01:15:07.640 | There's a rebound increase in melatonin.

01:15:09.460 | So that could be the cause of that effect.

01:15:11.760 | You have to see what works for you.

01:15:13.320 | But if you do the ice bath early in the day

01:15:16.260 | and then get out, you will experience a more rapid rise

01:15:20.040 | or cold shower early in the day,

01:15:21.180 | a more rapid rise in your body temperature

01:15:25.120 | that will phase advance your clock

01:15:27.140 | and make it easier to get up early the following day.

01:15:30.300 | So for those of you that are having trouble getting up

01:15:33.060 | and this is going to almost sound laughable

01:15:34.580 | but a cold shower first thing in the morning

01:15:36.420 | will wake you up but that's waking you up

01:15:38.740 | in the short term because of a different mechanism

01:15:41.580 | which I'll talk about in a moment.

01:15:42.980 | But it also is shifting your clock.

01:15:44.660 | It's phase advancing your clock

01:15:47.220 | in a way that makes you more likely

01:15:49.460 | to get up earlier the next day, okay?

01:15:52.380 | So in other words, increasing your temperature

01:15:54.620 | by getting in an ice bath or cold shower or exercising

01:15:59.040 | which causes a compensatory increase in body temperature.

01:16:03.000 | Think about the normal pattern of body temperature,

01:16:05.180 | low around 4.30, 5 a.m., starts to peak right around waking,

01:16:09.220 | excuse me, starts to increase right around waking,

01:16:11.620 | then steep slope, steep slope to a peak

01:16:13.840 | around 4 to 6 p.m. and then drops off.

01:16:16.340 | If you introduce an increase in body temperature

01:16:18.460 | by way of cold exposure early in the day,

01:16:20.980 | let's say 6 a.m. or 5 a.m. if you're masochistic enough

01:16:25.960 | to get into a cold shower at that time, more power to you,

01:16:28.740 | it's going to make you want to wake up about half hour

01:16:31.740 | to an hour earlier the next day than you normally would.

01:16:34.140 | Whereas if you do it while your temperature is falling,

01:16:37.020 | it will tend to delay and make your body perceive

01:16:39.420 | as if the day is getting longer.

01:16:41.300 | These are phase advances and phase delays.

01:16:43.480 | We're going to get into this in far more detail

01:16:45.560 | when we talk about jet lag and shift work in episode four

01:16:48.700 | as well as other things.

01:16:50.260 | But temperature is, again, it's not just one tool

01:16:54.240 | to manipulate wake-up time and circadian rhythm

01:16:57.560 | and metabolism, it is the effector.

01:17:00.140 | It is the way that the central circadian clock

01:17:02.240 | impacts all the cells and tissues of your body.

01:17:04.380 | If you want to read further about this

01:17:06.080 | and you're really curious about the role of temperature,

01:17:08.120 | work by Joe Takahashi,

01:17:09.740 | who used to be at Northwestern University

01:17:12.480 | and is now at UT Southwestern in Dallas,

01:17:15.680 | incredible scientist and has really worked out

01:17:19.180 | a lot of the mechanisms around temperature

01:17:20.720 | and circadian rhythms.

01:17:22.640 | You can just Google his name

01:17:23.920 | and you'll see a whole bunch of studies there.

01:17:26.360 | I want to talk about cold and cold exposure

01:17:30.140 | because there's a great misconception about this

01:17:32.840 | that actually you can leverage once you understand

01:17:35.780 | how to use cold to either increase thermogenesis

01:17:39.840 | and fat loss, metabolism,

01:17:42.040 | or you can use it for stress mitigation and mood.

01:17:45.080 | And it really depends on one simple feature

01:17:47.380 | of how you approach the ice bath or cold shower.

01:17:49.780 | If you get into an ice bath or cold shower

01:17:54.000 | and you are calming yourself,

01:17:56.080 | you're actively calming the autonomic nervous system,

01:17:58.440 | maybe through some deep breathing,

01:17:59.920 | maybe through visualization, maybe you sing a song.

01:18:02.700 | People do this stuff.

01:18:04.160 | They use various tools.

01:18:05.320 | Some people find paying attention to an external stimulus

01:18:08.160 | is more helpful.

01:18:09.800 | Thinking about something, not the experience of the cold.

01:18:12.380 | Other people find that directly experiencing the cold

01:18:14.780 | in its most intense form

01:18:15.820 | and kind of going into the cold, quote unquote,

01:18:18.740 | is the best way to approach it.

01:18:19.840 | It really varies for people.

01:18:21.720 | There's no right or wrong way to go about this.

01:18:24.180 | But the goal of using cold exposure for stress inoculation

01:18:28.100 | and to raise your stress threshold

01:18:30.800 | to be able to tolerate heightened levels

01:18:32.860 | of real life stress, not the ice bath,

01:18:35.640 | but real life stress like work stress

01:18:37.400 | and relational stress, et cetera,

01:18:39.160 | is by suppressing the activation

01:18:43.840 | of the so-called sympathetic nervous system,

01:18:46.360 | meaning the alertness or stress system.

01:18:48.360 | That involves buffering

01:18:51.640 | or trying to resist the shiver response.

01:18:53.720 | The shiver response is an autonomic response

01:18:56.000 | designed to generate heat, presumably,

01:18:59.080 | and actually that is what it does,

01:19:00.960 | in order to counter the cold.

01:19:03.120 | So when you use cold exposure

01:19:05.740 | and you're kind of muscling through it

01:19:07.340 | or you're learning to relax within it

01:19:09.100 | as a form of stress inoculation,

01:19:11.440 | that's great and works quite well for that purpose.

01:19:14.560 | And there's a reason why cold exposure

01:19:16.440 | is used in a variety of forms of military stress inoculation,

01:19:20.580 | most famous of which, of course,

01:19:21.760 | is the Navy Seal Buds Test, really,

01:19:25.980 | which is screening procedure for becoming a seal,

01:19:27.760 | involves a lot of exposure to cold water.

01:19:29.820 | However, if you're interested in using cold exposure

01:19:35.320 | for fat loss and thermogenesis,

01:19:37.680 | you want to do the exact opposite thing.

01:19:40.580 | There was a paper published in "Nature" two years ago,

01:19:43.920 | which showed that cold-induced shiver,

01:19:47.400 | the actual physical shiver,

01:19:50.400 | activates the release of a chemical in the body

01:19:53.640 | from muscle called succinate, S-U-C-C-I-N-A-T-E.

01:19:58.640 | Succinate travels in the bloodstream

01:20:02.200 | and then goes and activates a particular category of fat,

01:20:05.880 | not the typical kind of pink or white fat

01:20:08.020 | that we think of as like blubber in humans,

01:20:09.960 | the stuff that people seem to generally want less of,

01:20:12.700 | except for those genetic freaks

01:20:15.640 | that seem to have none of it,

01:20:16.740 | depending on what they consume.

01:20:18.080 | Congratulations.

01:20:19.160 | Brown fat is called brown fat

01:20:23.160 | because it's actually dark under the microscope.

01:20:25.400 | It's rich with mitochondria,

01:20:28.100 | and it exists mostly between the scapulae

01:20:30.000 | and in the upper neck,

01:20:31.080 | and it generates thermogenesis and heat in the body.

01:20:35.800 | It's rich with a certain category of adrenergic receptor.

01:20:39.980 | Incidentally, epinephrine binds to adrenergic receptors.

01:20:46.900 | These brown fat cells increase metabolism.

01:20:50.280 | It's called brown fat thermogenesis and cause fat burning,

01:20:54.620 | burning of other kinds of fat, the pink and white fat.

01:20:57.880 | So what does this all mean?

01:20:58.780 | This means if you want to use the ice bath

01:21:01.360 | in order to increase metabolism, shiver away.

01:21:04.580 | If you want to use the ice bath or cold shower

01:21:06.620 | in order to stress inoculate, resist the shiver

01:21:10.380 | and learn to stay calm or quote unquote muscle through it.

01:21:14.320 | Now, I don't know that anyone's ever really talked

01:21:15.900 | about this publicly because I think the data are so new,

01:21:19.760 | and I think that people assume that the ice bath

01:21:22.320 | or cold exposure is just one thing.

01:21:24.200 | Here, I've talked about it three ways

01:21:26.180 | to shift your circadian rhythm depending on whether

01:21:28.320 | or not you're doing it early in the day

01:21:29.960 | while your temperature is still rising or at its peak

01:21:33.520 | or after that peak in order to extend the perception

01:21:38.800 | of your day as continuing and make you want

01:21:41.720 | to go to sleep later and wake up later.

01:21:45.360 | Now, and then the third way, of course,

01:21:47.160 | is to either activate brown fat thermogenesis

01:21:49.800 | and increase metabolism.

01:21:51.040 | I suppose the fourth way would be

01:21:52.460 | to increase stress tolerance or stress threshold, okay?

01:21:57.460 | But remember, temperature is the effector

01:22:01.100 | of circadian rhythms.

01:22:02.480 | Light is the trigger.

01:22:03.880 | The suprachiasmatic nucleus is the master circadian clock

01:22:07.960 | that mediates all these changes,

01:22:10.280 | also influenced by non-photic influence like exercise

01:22:13.400 | and feeding and things of that sort,

01:22:15.620 | but temperature is the effector.

01:22:17.300 | Now, you can also shift your circadian rhythm with eating.

01:22:21.700 | When you travel and you land in a new location

01:22:24.760 | and your schedule is inverted 12 hours,

01:22:27.720 | one way that we know you can shift your rhythm more quickly

01:22:30.580 | is to get onto the local meal schedule.

01:22:32.840 | Now, that probably has to do with two effects.

01:22:34.400 | One are changes in temperature,

01:22:36.160 | eating-induced increases in body temperature.

01:22:39.600 | Now, you should understand why that would work,

01:22:41.440 | as well as eating has this anticipatory secretion

01:22:45.240 | of hypercretinorexin that I talked about earlier.

01:22:49.500 | So if this is getting a little too down in the weeds,

01:22:51.800 | don't worry about it.

01:22:53.400 | I will get more into this in episode four

01:22:55.520 | of how to shift one's rhythm,

01:22:56.800 | but I would love for people to understand

01:22:58.560 | that light and temperature are the real heavy-duty levers

01:23:02.360 | when it comes to moving your circadian rhythm

01:23:04.140 | and sleep times and activity schedules.

01:23:06.300 | And exercise and feeding can help,

01:23:08.660 | but really temperature and light,

01:23:10.420 | with light being the primary one,

01:23:11.700 | are the most important

01:23:13.500 | when it comes to sleep and wakefulness.

01:23:16.400 | Many people asked questions about food and neurotransmitters

01:23:20.560 | and how those relate to sleep, wakefulness, and mood,

01:23:23.660 | which is essentially 25 hours of content for me to cover,

01:23:28.660 | but I'm going to try and distill out

01:23:30.060 | the most common questions.

01:23:31.420 | We've talked a lot about neuromodulators

01:23:34.100 | like dopamine, acetylcholine, and norepinephrine.

01:23:37.060 | You may notice in those discussions

01:23:39.480 | that the precursors to say serotonin is tryptophan.

01:23:43.220 | Tryptophan actually comes from the diet.

01:23:44.920 | It comes from the foods that we eat.

01:23:46.660 | Tyrosine is the precursor to dopamine.

01:23:51.020 | It comes from the foods that we eat.

01:23:53.160 | And then once we ingest them,

01:23:55.440 | those compounds circulate

01:23:58.400 | to a variety of different cells and tissues,

01:24:01.040 | but it is true that our food and the particular foods we eat

01:24:04.640 | can influence things like neuromodulator levels

01:24:08.100 | to some extent, it's not the only way,

01:24:10.860 | because there are also enzymes and biochemical pathways

01:24:13.580 | that are going to regulate

01:24:14.460 | how much tyrosine gets converted into dopamine.

01:24:17.300 | And there are elements of the dopaminergic neurons,

01:24:19.940 | the dopamine neurons themselves that are electrical

01:24:22.120 | that have influence on this as well.

01:24:24.060 | But there are a couple fair assumptions that we can make.

01:24:28.480 | First of all, nuts and meats, in particular red meats,

01:24:32.920 | tend to be rich in things like tyrosine, right?

01:24:36.620 | That tells you right there that because

01:24:38.520 | tyrosine is the precursor of dopamine

01:24:40.240 | and dopamine is the precursor of norepinephrine

01:24:42.840 | and epinephrine, that those foods tend to lend themselves

01:24:47.620 | toward the production of dopamine and epinephrine

01:24:51.820 | and the sorts of things that are associated

01:24:53.960 | with wakefulness.

01:24:55.700 | Now, of course, the volume of food that we eat

01:24:58.220 | also impacts our wakefulness.

01:24:59.600 | If we eat a lot of anything,

01:25:01.440 | whether or not it's ribeye, steaks, rice, or cardboard,

01:25:05.500 | please don't eat cardboard,

01:25:06.760 | your stomach, if it's very distended,

01:25:08.900 | will draw a lot of blood into your gut

01:25:11.180 | and you will divert blood from other tissues

01:25:13.660 | and you'll become sleepy.

01:25:14.740 | So it's not just about food content,

01:25:16.280 | it's also about food volume, all right?

01:25:18.660 | Fasting states generally are associated

01:25:21.780 | with more alertness, epinephrine, and so forth.

01:25:24.740 | And fed states are generally associated

01:25:28.260 | with more quiescence and relaxation,

01:25:30.460 | serotonin and the kind of things that lend themselves

01:25:33.660 | more towards sleep and less toward alertness.

01:25:37.180 | Foods that are rich in tryptophan

01:25:39.160 | tend to be things like white meat turkey,

01:25:40.780 | also complex carbohydrates.

01:25:43.060 | So if you like, you can start experimenting,

01:25:46.720 | depending on what foods you eat,

01:25:48.620 | you can start experimenting with carbohydrate-rich meals

01:25:53.060 | for accessing sleep and more depth of sleep.

01:25:57.900 | This is actually something that I personally do.

01:25:59.660 | I tend to eat pretty low carb-ish during the day.

01:26:01.960 | I actually fast until about noon,

01:26:03.920 | not because I have to work to do that,

01:26:05.520 | but because I'd rather just drink caffeine

01:26:07.180 | and water during that time.

01:26:08.860 | And then sometime around noon,

01:26:10.260 | I can't take it anymore and I'm hungry and I eat,

01:26:12.840 | and I try and eat low carb-ish

01:26:14.700 | unless I've worked out extremely hard

01:26:16.520 | in the previous two hours, which I rarely do,

01:26:19.680 | although I do sometimes.

01:26:21.460 | And that meal is then designed to prolong

01:26:25.020 | my period of wakefulness into the late afternoon.

01:26:27.100 | And then sometime around dinnertime,

01:26:29.160 | which for me is around 6.30, 7 p.m., 8 p.m.,

01:26:31.820 | sometimes as late as 9 p.m.,

01:26:33.300 | I tend to eat things like white meat, fish,

01:26:35.680 | pastas, rice, and that kind of thing.

01:26:38.180 | My favorite food of all for accessing tryptophan

01:26:42.200 | is actually a starch.

01:26:43.280 | It's actually a vegetable, and it's the croissant,

01:26:45.940 | which is my favorite vegetable.

01:26:47.660 | I don't eat those all the time, but I love them,

01:26:50.440 | and they seem to increase dopamine as well.

01:26:53.140 | Never actually done the mass spectrometry on a croissant,

01:26:55.940 | but they definitely increase tryptophan

01:26:58.220 | and relaxation for me.

01:27:00.540 | In all seriousness, low carbohydrate/fasted/ketogenic diets

01:27:05.540 | tend to lend themselves toward wakefulness

01:27:07.520 | by way of increasing epinephrine, norepinephrine,

01:27:11.380 | adrenaline, dopamine, and things of that sort.

01:27:13.620 | Carbohydrate-rich meals,

01:27:16.580 | and I suppose we should talk about meals as opposed to diet,

01:27:19.020 | tend to lend themselves more toward tryptophan, serotonin,

01:27:23.260 | and more lethargic states.

01:27:25.260 | There is very limited evidence that I am aware of

01:27:29.660 | that carbohydrates should be eaten at one time a day

01:27:32.340 | as it relates to metabolism, et cetera.

01:27:35.860 | I'm sure that will open up a certain amount of debate.

01:27:39.140 | If you work out very hard and you deplete glycogen,

01:27:41.420 | then this all changes.

01:27:42.960 | So some people are working out very hard

01:27:44.300 | in depleting glycogen, other people are not.

01:27:46.880 | That gets way outside the context

01:27:48.820 | of this particular podcast.

01:27:50.460 | But yes, indeed, different foods can bias

01:27:52.940 | different neuromodulators and thereby can modulate

01:27:56.400 | our waking or our feelings of lethargy and sleepiness.

01:27:59.780 | There are a couple of effects of food that are independent,

01:28:06.200 | or I should say a couple of effects of eating,

01:28:07.820 | 'cause the food won't do it

01:28:08.760 | when it's sitting across the table,

01:28:09.920 | but of eating that are powerful for modulating

01:28:14.280 | circadian rhythm, wakefulness, et cetera.

01:28:16.720 | And that's because every time we eat,

01:28:18.000 | we get eating-induced thermogenesis

01:28:20.580 | regardless of what we eat.

01:28:21.960 | Now, the eating-induced thermogenesis

01:28:24.220 | and increase in metabolism,

01:28:25.540 | which is an increase in temperature really,

01:28:28.380 | is probably greatest for amino acid-rich foods like meats,

01:28:33.380 | but also other types of foods.

01:28:37.240 | It's a minimal increase in body temperature

01:28:39.520 | compared to say cold exposure or exercise.

01:28:42.800 | Now, whether or not it's a quarter of a degree

01:28:44.940 | or half a degree or a degree,

01:28:46.080 | it really depends on the individual.

01:28:48.000 | And of course there are blood sugar effects.

01:28:50.360 | There are things like whether or not you are type one

01:28:54.420 | or type two diabetic,

01:28:55.460 | whether or not you're insulin resistant,

01:28:56.940 | whether or not like there's a kid who interns

01:29:00.240 | on the podcast here, who's 17 years old,

01:29:03.120 | and I'm convinced that he can eat anything.

01:29:05.740 | And he just seems to like burn it up and he's growing it.

01:29:09.040 | Every time, actually the other day,

01:29:10.440 | he walked into the other room and two days later,

01:29:12.640 | he walked out of the same room.

01:29:14.080 | He came out in between, of course.

01:29:15.320 | But, and I was like, he grew, he was like, you know,

01:29:18.480 | but he's at that stage where he's just growing.

01:29:21.880 | Food is going to affect a teenager very differently

01:29:23.720 | than it's going to affect a full grown person.

01:29:26.000 | So, in general, starchy carbohydrates, white meats,

01:29:31.000 | such as turkey, some fish, increased tryptophan,

01:29:33.900 | therefore serotonin, therefore more lethargic states,

01:29:37.400 | more calm.

01:29:38.340 | Meat, nuts, and there are probably some plant-based foods

01:29:42.640 | that I'm not aware of, and I apologize,

01:29:44.560 | I should read up on this,

01:29:45.980 | that also are high in tyrosine that can increase things

01:29:50.000 | like dopamine, norepinephrine, epinephrine, alertness.

01:29:53.840 | So, you can vary these however you like.

01:29:56.420 | Most people, I think, are eating a variety

01:29:58.360 | of these things in given meals.

01:30:00.320 | And there are other parameters of nutrition

01:30:02.580 | that are important too.

01:30:03.800 | Volume of food for the reasons I mentioned before,

01:30:05.920 | the volume of food in the gut,

01:30:08.040 | less food in the gut, whether or not it's empty

01:30:09.980 | or a small amount of food will tend to correlate

01:30:12.000 | with wakefulness.

01:30:12.940 | Large volumes of food of any kind will tend to correlate

01:30:18.120 | and drive the calming response,

01:30:21.000 | and that's by way of this nerve pathway called the vagus.

01:30:23.080 | We actually have sensory fibers in the gut

01:30:25.100 | that communicate to a little protrusion of neurons

01:30:27.800 | that sit right next to the juggler

01:30:28.840 | called the nodose ganglia, N-O-D-O-S-E.

01:30:32.460 | Unlike Costello, it's nodose, right now he's aldose.

01:30:37.020 | Nodose actually means having many protrusions,

01:30:39.840 | and it's like kind of a lumpy collection of neurons.

01:30:42.380 | A ganglia is just a collection of neurons,

01:30:43.700 | and then it goes into the brain stem

01:30:46.240 | and then forward in the brain to the areas of the brain

01:30:48.400 | that are involved in production of various neuromodulators.

01:30:52.780 | So what we eat and the volume of food

01:30:57.160 | are both signaling to the brain.

01:30:59.240 | It's not just one or the other.

01:31:01.180 | And then there's also this eating-induced thermogenesis,

01:31:04.240 | and now you know from the discussion about temperature

01:31:06.160 | that if you're eating early in the day,

01:31:08.040 | you're tending to shift your rhythm earlier

01:31:10.040 | so that you'll want to wake up earlier the next day

01:31:13.420 | if you're eating very late in the day,

01:31:15.320 | even if you can fall asleep after that,

01:31:17.580 | there's a tendency for you to want to sleep

01:31:19.180 | later the next day.

01:31:20.680 | Now, this of course is all going to be constrained

01:31:23.280 | by when your kids need to eat

01:31:24.720 | and when your spouse needs to eat

01:31:25.840 | and when your friends need to eat,

01:31:26.760 | or if you live alone or what other things you're doing.

01:31:28.860 | If you're like me and you kind of don't eat until noon

01:31:31.340 | then eat sometime around noon

01:31:32.600 | and then I'm terrible about meals,

01:31:33.880 | I just start eating the ingredients

01:31:35.200 | while I'm supposed to be cooking

01:31:36.160 | and then eventually they're all gone,

01:31:37.600 | and I guess that's a meal.

01:31:39.120 | It varies.

01:31:41.360 | Some people are neurotically attached

01:31:43.200 | to a particular meal schedule.

01:31:45.280 | Some people are not.

01:31:46.100 | I take my light exposure schedule far more seriously

01:31:49.220 | than I take my meal schedule.

01:31:50.860 | Although in general, I try and eat healthy foods

01:31:53.080 | for the most part, croissants included.

01:31:55.080 | I was asked several times whether or not

01:31:58.280 | men and women or males and females differ

01:32:01.040 | in terms of these neurotransmitter phenotypes

01:32:03.100 | and the rhythms of sleep and temperature.

01:32:05.840 | We could probably devote a whole month

01:32:09.360 | and we probably will devote an entire month

01:32:11.080 | to what are called sex differences

01:32:13.120 | because those tend to be related to things

01:32:14.960 | we absolutely know like XX or XY chromosomes

01:32:18.020 | or XYY in some cases or XX chromosomes

01:32:20.360 | as opposed to gender, sex and karyotype as we call it,

01:32:24.920 | genetic makeup is crystal clear.

01:32:27.040 | There are things that correlate with one or the other

01:32:32.080 | but it's complicated and it's not something

01:32:34.400 | that's been explored in what I think is enough detail.

01:32:38.180 | Actually recently, I guess it was about five years ago,

01:32:42.200 | the National Institutes of Health made it a mandate

01:32:45.240 | that all studies use sex as a biological variable

01:32:48.780 | and actually explore both sexes of mice,

01:32:51.360 | both sexes of humans when doing any kind of study

01:32:53.500 | because there was a bias towards only using male animals

01:32:56.340 | or male subjects prior to that time.

01:32:58.680 | So a lot of data are now coming out

01:33:00.200 | revealing important sex differences

01:33:02.600 | that I think are going to have powerful impact

01:33:05.160 | on health practices, et cetera, response to drugs,

01:33:07.720 | response to different sleep schedules, et cetera.

01:33:10.740 | Perhaps the most salient and obvious one

01:33:13.220 | is that during pregnancy,

01:33:14.580 | females experience a whole range

01:33:18.420 | of endocrine and neural effects

01:33:21.020 | and we definitely will devote a month

01:33:23.000 | to pregnancy and childbirth and child rearing.

01:33:25.620 | And for that, I'd really like to bring in some experts.

01:33:29.040 | I've got terrific colleagues at Stanford and elsewhere

01:33:31.060 | that work on these things

01:33:32.100 | so that we can go into those in more depth.

01:33:33.560 | So I'm not blowing off those questions,

01:33:35.660 | I'm just kind of pushing them down the road a little bit

01:33:38.220 | where I can give you a more thorough answer.

01:33:42.320 | So as we finish up,

01:33:43.760 | I just want to offer you the opportunity

01:33:46.160 | to do an experiment.

01:33:48.040 | We've talked about a lot of variables

01:33:49.800 | that can impact sleep and wakefulness.

01:33:51.920 | And in keeping with the theme of the podcast,

01:33:53.800 | we are going to continue

01:33:55.280 | to talk about sleep and wakefulness and tools for those

01:33:58.340 | and the science behind those tools as we go forward.

01:34:01.580 | But there are really just four simple parameters

01:34:05.120 | that you have control over

01:34:07.440 | that you can immediately start to record and take note of,

01:34:12.440 | just to see how you're doing with these things.

01:34:15.300 | With no judgment or perhaps no change

01:34:18.520 | to what you're actually doing.

01:34:20.120 | It might be interesting, just a suggestion,

01:34:22.820 | to write down for each day

01:34:26.240 | when you went outside to get sunlight

01:34:28.980 | and when you did that relative to waking.

01:34:30.980 | So you would write down,

01:34:31.920 | like the way I do this in my calendar is I'll write down

01:34:34.280 | that I don't get exact about it.

01:34:36.120 | I might say I woke up at 6.15

01:34:39.360 | and then I guess I'll put a W 6.15

01:34:41.840 | and then SL for sunlight.

01:34:44.860 | Now you will sometimes get outside right away.

01:34:46.720 | Other times I'm less good at that

01:34:48.080 | and I'll go out around, I don't know, let's say seven.

01:34:51.000 | And for how long?

01:34:52.480 | Maybe like 10, 15 minutes or so.

01:34:54.980 | And then I'll put a little check

01:34:56.680 | at roughly the times that I eat my so-called meals.

01:34:59.840 | Although as I mentioned,

01:35:00.680 | sometimes my meals are a bunch of small checks

01:35:02.640 | that just kind of extend through the late hours of the day.

01:35:05.200 | Yours might be more confined to certain times.

01:35:09.840 | And then you might just take note of when you exercised,

01:35:14.160 | just put down an E for when you exercise,

01:35:16.300 | weight training or aerobic exercise.

01:35:19.400 | And you might note when you might've felt chilled or cold,

01:35:23.060 | if you do, or you might've felt particularly hot,

01:35:25.760 | or if you woke up in the middle of the night

01:35:26.920 | when you felt particularly hot.

01:35:27.960 | And then the last thing you might want to do

01:35:29.680 | is just write down if and when you did

01:35:31.980 | a non-sleep deep rest protocol, NSDR protocol,

01:35:34.640 | that could be meditation, that could be yoga nidra,

01:35:37.040 | that could be hypnosis.

01:35:38.520 | Anything that you're using to deliberately

01:35:43.160 | teach your nervous system how to go from more alertness

01:35:45.920 | to more calmness in the waking state,

01:35:48.040 | even if it's waking up in the middle of the night

01:35:49.400 | and doing an NSDR protocol or in the afternoon

01:35:52.100 | or first thing in the morning to recover some sleep

01:35:54.600 | and ability to perform DPOs that you might've lost

01:35:57.400 | from a minimal or poor night's sleep.

01:35:59.500 | So you're going to write down when you woke up,

01:36:01.620 | when you viewed sunlight,

01:36:03.320 | that might be in the morning and the evening

01:36:04.720 | or just the morning,

01:36:05.800 | hopefully it's the morning and the evening,

01:36:07.480 | when you exercised, when you ate your meals.

01:36:10.440 | And using a simple record keeping scheme

01:36:12.620 | like W for waking, SL for sunlight,

01:36:16.280 | maybe you come up with a system where it's a check

01:36:18.100 | or an X or something for exercise.

01:36:20.240 | This is not designed to make you neurotically attached

01:36:22.880 | to tracking all your behaviors and everything you do.

01:36:27.880 | I, for instance, don't track what I eat in particular,

01:36:30.680 | I kind of know what works for me

01:36:32.440 | and I just try and stay within that range.

01:36:35.640 | But by doing this, you can start to reveal

01:36:38.080 | some really interesting patterns.

01:36:39.840 | Patterns that no answer that I could provide you

01:36:42.920 | about any existing tool or protocol could counter.

01:36:46.800 | It's really about taking the patterns of behaviors

01:36:51.480 | of waking and light viewing and eating and exercise

01:36:54.840 | and superimposing that on what you're learning

01:36:58.800 | in this podcast and elsewhere, of course,

01:37:01.040 | and what you already know.

01:37:02.400 | And trying to see where certain problems

01:37:05.640 | or pain points might be arising.

01:37:07.000 | Maybe you're eating really late in the day

01:37:08.720 | and you're waking up in the middle of the night really warm.

01:37:10.520 | Well, now you would say, well, that could be due

01:37:12.680 | to kind of an increase in temperature

01:37:14.840 | that is extending my day.

01:37:17.400 | Or maybe you start to find that using cold exposure

01:37:21.220 | early in the day is great for you, but using it late,

01:37:24.080 | if it's too late in the day, that's not great.

01:37:25.920 | Or if you're into the sauna or it's even like some people,

01:37:30.160 | including myself, if I take a hot shower

01:37:31.880 | or sit in a hot tub or a sauna late at night,

01:37:34.420 | well, then I get a compensatory decrease in body temperature

01:37:37.680 | and I sleep great provided I hydrate well enough

01:37:40.280 | 'cause that can be kind of a dehydrating thing

01:37:42.000 | to sit in hot conditions.

01:37:44.280 | But if I do the sauna early in the day,

01:37:46.640 | unless I exercise immediately afterward,

01:37:49.720 | then I tend to get the temperature drop, which makes sense

01:37:52.360 | because when you get in the sauna, you get vasodilatation,

01:37:55.320 | you throw off a lot of heat,

01:37:56.440 | and then you generally get a compensatory drop

01:37:58.140 | in temperature.

01:37:58.980 | If you do that early in the day,

01:37:59.800 | that's right about the time that that temperature

01:38:02.280 | is trying to entrain the circadian clocks of your body.

01:38:04.960 | That's what happens to me.

01:38:06.320 | Other people, it might be slightly different.

01:38:08.080 | And some people have more resilient systems than others.

01:38:12.440 | So I just encourage you to start becoming scientists

01:38:15.760 | of your own physiology, of your own brain and body

01:38:19.320 | and seeing how the various tools

01:38:20.640 | that you may or may not be using

01:38:22.640 | are affecting your patterns of sleep,

01:38:25.400 | your patterns of attention and wakefulness.

01:38:27.720 | It's vitally important that if you do this,

01:38:30.360 | that you know that it's not about trying to get

01:38:32.840 | onto an extremely rigid schedule.

01:38:35.760 | It's really about trying to identify variables

01:38:38.320 | that are most powerful for you

01:38:40.320 | and that push you in the direction that you want to go

01:38:42.560 | and changing the variables that are pushing your body

01:38:45.720 | and your mind in the directions that you don't want to go.

01:38:47.880 | Self-experimentation is something

01:38:49.640 | that should be done slowly, carefully.

01:38:52.200 | You don't want to be reckless about this.

01:38:54.000 | And this is where I would say manipulating one

01:38:57.600 | or two variables at a time is really going to be best

01:38:59.860 | as opposed to changing a dozen things all at once

01:39:02.640 | to really identify what it is that's most powerful for you.

01:39:05.760 | As always, thank you so much for your questions.

01:39:09.840 | We are going to continue to answer questions.

01:39:11.980 | I certainly didn't get to all of them,

01:39:13.220 | but we tried to get to most all of the ones

01:39:15.440 | that were frequently asked.

01:39:17.680 | Episode four of the podcast,

01:39:19.400 | I'm going to get into shift work, jet lag

01:39:22.400 | and age dependent changes in sleeping

01:39:26.320 | and wakefulness and cognition.

01:39:28.420 | So for those of you with kids,

01:39:30.480 | for those of you that are kids,

01:39:32.060 | for those of you with older relatives

01:39:35.000 | or who might be older, meaning probably when you start

01:39:38.800 | to get into late sixties, seventies and eighties

01:39:40.920 | is when there's some marked biological shifts

01:39:43.200 | in temperature regulation and things that relate to sleep.

01:39:46.100 | And for those of you that travel,

01:39:49.240 | we're going to talk about jet lag.

01:39:50.720 | The shift work discussion might seem only relevant

01:39:53.360 | to those that work nights, but actually that's not the case.

01:39:56.480 | Most people, because of the way they're interacting

01:39:58.600 | with devices, are actually in a form of shift work now

01:40:03.040 | where the days are certainly not nine to five

01:40:05.600 | so-called banker's hours.

01:40:07.000 | And then the lights are out at nine

01:40:08.680 | and they're asleep until 5 a.m.

01:40:10.560 | Some people have that schedule, most people do not.

01:40:12.820 | So episode four, we will go deeply into shift work,

01:40:16.640 | jet lag, age dependent changes in sleep alertness

01:40:19.560 | and cognition, and I will touch back

01:40:21.720 | on a few of your questions,

01:40:22.840 | but don't think that if your question wasn't answered

01:40:24.720 | during these office hours that we won't get to it.

01:40:26.880 | I absolutely will at some point.

01:40:28.840 | In addition to that, several of you have graciously asked

01:40:33.760 | how you can help support the podcast

01:40:35.520 | and we very much appreciate that.

01:40:37.600 | You can support the podcast by liking it on YouTube,

01:40:41.840 | by subscribing on YouTube,

01:40:43.780 | by recommending the YouTube videos to others,

01:40:46.480 | as well as subscribing and downloading the podcast on Apple

01:40:50.100 | where you can also leave a review and on Spotify

01:40:53.560 | or all three if you like.

01:40:55.800 | You can also help us by supporting our sponsors.

01:40:58.040 | So check out some of the sponsor links

01:40:59.500 | that were described at the beginning of the episode.

01:41:02.080 | And in general, recommending the podcast to people

01:41:04.660 | that you know and that you think would benefit

01:41:06.080 | from the information would be terrific.

01:41:08.300 | As always, I will be continuing to post on Instagram.

01:41:12.000 | You can expect another podcast episode out next Monday

01:41:15.320 | about the topics that we've been discussing this month.

01:41:17.940 | And above all, thank you for your interest in science.

01:41:20.840 | (upbeat music)

01:41:23.420 | (upbeat music)

Using Science to Optimize Sleep, Learning & Metabolism

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