Time Perception & Entrainment by Dopamine, Serotonin & Hormones

00:00:00.320 | - Welcome to the Huberman Lab Podcast,

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

00:00:04.880 | for everyday life.

00:00:05.900 | I'm Andrew Huberman,

00:00:10.140 | and I'm a professor of neurobiology and ophthalmology

00:00:12.960 | at Stanford School of Medicine.

00:00:14.920 | Today, we are talking about time perception.

00:00:18.040 | Our perception of time is perhaps the most important factor

00:00:21.920 | in how we gauge our life.

00:00:24.040 | That is, whether or not we think we are being successful,

00:00:26.960 | whether or not we are failing,

00:00:28.500 | whether or not we live in fear,

00:00:30.280 | whether or not we live in relation to things

00:00:32.440 | in a way that's positive.

00:00:33.680 | And the reason for that is that our perception of time

00:00:37.040 | is directly linked to the neurochemical states

00:00:39.840 | that control mood, stress, happiness, excitement,

00:00:44.040 | and of course, it frames the way

00:00:46.080 | in which we evaluate our past.

00:00:48.680 | So whether or not we think of our past

00:00:50.640 | as successful or unsuccessful, it frames our present,

00:00:54.640 | whether or not we think we are on track or off track,

00:00:57.380 | and it frames our sense of the future,

00:00:59.840 | whether or not we think we have a bright future,

00:01:02.480 | a dim future, or whether or not the future

00:01:04.520 | is very uncertain or not.

00:01:07.240 | Today, we're going to talk about

00:01:08.260 | the science of time perception,

00:01:10.260 | and we are going to talk about tools and protocols

00:01:13.200 | that you can use that can enhance your ability

00:01:17.000 | to dilate and contract time.

00:01:19.020 | What do we mean by dilate and contract time?

00:01:21.920 | We can control the speed at which we experience life.

00:01:25.460 | We can slow things down or we can speed

00:01:28.140 | our experience of life up,

00:01:29.880 | and we can do that in a very direct and dynamic way.

00:01:32.960 | It's actually not that hard

00:01:34.440 | once you understand how time perception works.

00:01:36.640 | So that's where we're headed.

00:01:37.520 | I think you're going to come away from today's episode

00:01:39.680 | with a lot of new knowledge,

00:01:41.800 | and certainly with many tools that you can try

00:01:44.400 | in your daily life, whether or not that's work, sport,

00:01:46.760 | relational, emotional, and so on.

00:01:49.400 | Before we begin our discussion about time perception,

00:01:52.400 | I'd like to answer some questions that I received

00:01:54.960 | related to the episode on fasting

00:01:57.060 | and time-restricted feeding.

00:01:58.860 | If you haven't seen that episode,

00:02:00.080 | this information should still be of use to you.

00:02:02.840 | Time-restricted feeding involves eating

00:02:05.000 | for a particular period of time in each 24-hour cycle

00:02:08.120 | that's fairly regular.

00:02:09.700 | So this would be an eight-hour most often

00:02:12.180 | or a 10-hour block.

00:02:13.260 | Some people do shorter feeding windows,

00:02:15.940 | but regardless, that feeding window is supposed to fall

00:02:18.040 | at more or less the same period within each 24-hour day.

00:02:20.800 | This has a number of positive effects on gene expression

00:02:23.800 | that regulate a number of positive effects

00:02:25.480 | on the different tissues of the body.

00:02:27.000 | And for some people, not all,

00:02:28.840 | but for some people makes weight loss easier

00:02:31.920 | because of the way that they are not eating

00:02:34.040 | for large periods of each 24-hour cycle.

00:02:36.800 | In any event, one of the major questions I got

00:02:39.460 | after that episode was do supplements break a fast?

00:02:44.000 | And during that episode, I talked about what breaks a fast

00:02:46.740 | is highly contextual.

00:02:48.260 | It basically boils down to whether or not

00:02:50.560 | something you ingest, whether it be liquid or food,

00:02:54.540 | increases your resting blood glucose,

00:02:56.460 | how much it increases that resting blood glucose,

00:02:58.980 | and how long that increase lasts.

00:03:01.760 | So you can check out the episode

00:03:02.960 | for more about what breaks a fast,

00:03:05.460 | but to address this issue about supplements

00:03:08.200 | and whether or not supplements a particular break of fast,

00:03:10.920 | many of the questions were about Athletic Greens.

00:03:13.560 | Athletic Greens is a sponsor of this podcast.

00:03:16.480 | It is also a terrific supplement that I had been taking

00:03:19.040 | for more than a decade before this podcast launched,

00:03:21.960 | and many people have been using

00:03:24.320 | and continue to use Athletic Greens.

00:03:26.840 | Does Athletic Greens break a fast?

00:03:28.920 | Well, that will somewhat depend on whether or not

00:03:31.040 | your resting blood glucose tends to run high or low,

00:03:34.240 | but for most people, including me, because I've measured it,

00:03:37.120 | ingesting Athletic Greens does not break a fast,

00:03:39.580 | and if it happens to break a fast,

00:03:41.180 | it would be a very transient break in fast.

00:03:43.800 | So without knowing your resting blood glucose levels

00:03:46.560 | on an individual basis, there's no way I can say for sure

00:03:49.040 | that it doesn't break a fast, but chances are it does not,

00:03:51.880 | because it doesn't contain much carbohydrate or sugar,

00:03:55.360 | and it doesn't tend to therefore pull you

00:03:58.680 | out of the molecular milieu

00:04:00.560 | associated with low blood glucose states.

00:04:04.240 | The other question I get is whether or not

00:04:05.960 | things like fish oil break a fast,

00:04:07.780 | and once again, this will be contextual,

00:04:10.960 | but because fish oil is a fat,

00:04:13.880 | mainly essential fatty acids, in particular EPA and DHA,

00:04:17.180 | those don't tend to raise blood glucose very much.

00:04:20.900 | In my case, having measured using

00:04:23.000 | a continuous glucose monitor, my resting blood glucose,

00:04:25.920 | fish oil does not in any way change

00:04:27.700 | my resting blood glucose.

00:04:29.640 | Chances are it won't do that for most people as well.

00:04:32.140 | So does fish oil break a fast?

00:04:33.840 | Chances are it does not.

00:04:36.200 | And of course, people wanted to know

00:04:37.840 | about pill type supplements, you know,

00:04:39.840 | caffeine and things that raise dopamine

00:04:41.960 | and their vitamins and minerals, in general,

00:04:44.220 | if something doesn't contain sugar

00:04:46.220 | or much carbohydrate of any kind,

00:04:49.280 | it's not going to raise blood glucose very much.

00:04:51.500 | Now, of course, protein can raise blood glucose

00:04:53.480 | and fat can too as well, although to a lesser extent.

00:04:57.240 | So again, this is all contextual,

00:04:59.000 | but at least by the logic that I just spelled out,

00:05:02.100 | athletic greens, fish oil, and most forms of supplements,

00:05:05.780 | provided they don't have any sugar or protein content,

00:05:08.700 | should not quote unquote break a fast.

00:05:11.720 | Before we begin, I'd like to emphasize

00:05:13.520 | that this podcast is separate from my teaching

00:05:15.760 | and research roles at Stanford.

00:05:17.540 | It is however, part of my desire and effort

00:05:19.800 | to bring zero cost to consumer information about science

00:05:22.400 | and science related tools to the general public.

00:05:25.000 | In keeping with that theme,

00:05:26.040 | I'd like to thank the sponsors of today's podcast.

00:05:28.840 | Our first sponsor is Roca.

00:05:30.920 | Roca makes eyeglasses and sunglasses

00:05:33.000 | that are of the absolute highest quality.

00:05:35.640 | I've spent a lifetime working on the visual system.

00:05:38.040 | And one of the key things about our visual system

00:05:40.040 | is that it's designed so that when you move into areas

00:05:42.960 | where it's sunny or where there are shadows,

00:05:45.640 | you can still see things with crystal clarity.

00:05:48.820 | Many sunglasses out there have the problem

00:05:50.980 | that you have to keep taking them off

00:05:52.640 | and putting them back on depending on the overall

00:05:55.160 | so-called ambient environment that you're in.

00:05:57.460 | Roca sunglasses have solved this problem.

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00:06:13.560 | So unlike a lot of performance glasses out there

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00:06:21.300 | and you can wear them running and cycling

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00:06:25.140 | If you'd like to try Roca glasses,

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00:06:29.280 | and enter the code Huberman to save 20% off your first order.

00:06:33.260 | Today's episode is also brought to us by Athletic Greens.

00:06:36.180 | Athletic Greens is an all-in-one vitamin mineral

00:06:38.460 | probiotic drink.

00:06:40.120 | I started using Athletic Greens way back in 2012,

00:06:43.140 | and so I'm delighted that they're sponsoring the podcast.

00:06:45.780 | The reason I started using Athletic Greens

00:06:47.700 | and the reason I still take Athletic Greens

00:06:49.220 | once or twice every day is that it covers

00:06:51.860 | all of my foundational needs for vitamins,

00:06:53.980 | minerals, and probiotics.

00:06:55.780 | In fact, when people ask me what supplements

00:06:58.060 | they should take, if I were going to recommend

00:07:00.260 | just one supplement, it would be Athletic Greens

00:07:02.340 | because of the enormous number of biological factors

00:07:05.640 | that it impacts in a positive way.

00:07:07.740 | As I mentioned, vitamins and minerals,

00:07:09.580 | the probiotics are really important

00:07:11.000 | for the gut microbiome and gut health,

00:07:13.180 | which is important for the immune system

00:07:15.380 | and for brain health and for mood

00:07:17.200 | and a number of other important factors,

00:07:19.100 | including hormones and so on.

00:07:20.920 | If you'd like to try Athletic Greens,

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00:07:43.580 | including blood lipid profiles and a number of other things.

00:07:46.560 | Again, go to athleticgreens.com/huberman

00:07:49.400 | to get the Athletic Greens, the five free travel packs,

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00:09:26.100 | So let's talk about time perception.

00:09:28.020 | And the most fundamental aspect of time perception

00:09:30.540 | is something called entrainment.

00:09:32.700 | Entrainment is the way in which your internal processes,

00:09:36.600 | your biology and your psychology,

00:09:39.040 | are linked to some external thing.

00:09:42.300 | And the most basic form of entrainment

00:09:44.420 | that we are all a slave to all year round

00:09:48.660 | for our entire life are so-called circannual rhythms.

00:09:53.720 | We have neurons, nerve cells in our eye, in our brain,

00:09:58.400 | and in our body that are marking off the passage of time

00:10:03.240 | throughout the year,

00:10:04.380 | literally a calendar system in your brain and body.

00:10:07.160 | And the way this works is beautifully simple.

00:10:09.960 | Light seen by your eyes inhibits,

00:10:15.440 | meaning it reduces the amount of a hormone

00:10:17.920 | released in your brain called melatonin.

00:10:21.360 | Melatonin has two major functions.

00:10:23.880 | One function is to make you sleepy at night,

00:10:26.140 | and the other is to regulate

00:10:27.540 | some of the other hormones of the body,

00:10:29.700 | in particular, testosterone and estrogen.

00:10:31.740 | When we view light,

00:10:35.060 | we reduce the amount of melatonin released.

00:10:37.060 | In fact, if you wake up in the middle of the night,

00:10:38.900 | when melatonin typically is pretty high

00:10:41.000 | in your brain and body,

00:10:42.180 | and you flip on a bright light in the bathroom,

00:10:44.580 | your melatonin levels crash down to almost zero

00:10:47.820 | and stay there.

00:10:49.500 | Light is a very powerful modulator of melatonin,

00:10:52.820 | and light inhibits melatonin.

00:10:54.940 | Throughout the year, depending on where you live,

00:10:59.020 | day length varies, and as a consequence,

00:11:02.060 | the amount of light from the sun

00:11:04.820 | that is available to you varies.

00:11:07.260 | So when days are long,

00:11:09.580 | the amount of melatonin in your brain and body

00:11:11.760 | that's released tends to be less.

00:11:14.380 | There's less of it,

00:11:15.240 | and it's released for shorter amounts of time, okay?

00:11:18.340 | Because light inhibits melatonin.

00:11:20.460 | When days are very short,

00:11:22.320 | the amount of melatonin that's released

00:11:24.400 | and the duration that that melatonin exists

00:11:26.600 | in your brain and body tends to be much longer.

00:11:29.320 | So melatonin correlates with day length,

00:11:32.780 | and if we are viewing more light,

00:11:36.100 | we have less melatonin, we view less light,

00:11:38.580 | we have more melatonin.

00:11:40.440 | You see different amounts of light each day,

00:11:45.440 | but we have a process in our brain and body

00:11:48.880 | that averages the amount of light that you're seeing,

00:11:51.260 | both from artificial sources and from sunlight,

00:11:53.960 | and measures that off.

00:11:55.640 | And it's so exquisitely precise

00:11:58.640 | that for a given, say, eight-hour day in the spring,

00:12:03.180 | because spring in the Northern Hemisphere or elsewhere,

00:12:05.860 | days are getting longer,

00:12:07.240 | that means that the amount of melatonin

00:12:11.140 | is getting progressively less and less,

00:12:13.400 | and that signal is conveyed to all the systems

00:12:15.660 | of your brain and body.

00:12:17.060 | And this is why most people, not all,

00:12:18.860 | but most people feel like they have more energy

00:12:21.240 | in the spring.

00:12:22.860 | Conversely, when you have an eight-hour day in the winter,

00:12:27.700 | the amount of melatonin that corresponds

00:12:29.860 | to that eight-hour day

00:12:31.660 | is getting progressively greater and greater,

00:12:34.460 | because why?

00:12:35.460 | Days are getting shorter,

00:12:36.580 | so melatonin is increasing from day to day to day.

00:12:40.480 | Every cell and system of your body pays attention to this,

00:12:42.880 | and as a consequence, most people, not all,

00:12:44.660 | but most people feel they have a little less

00:12:46.940 | or sometimes a lot less energy

00:12:48.580 | and a slightly lower mood in the winter months.

00:12:51.480 | Now, there are exceptions to this, of course,

00:12:53.780 | but the melatonin signal is the way

00:12:56.620 | in which your internal state, your mood,

00:13:00.220 | your sense of energy, even your appetite,

00:13:03.340 | is entrained, is matched to some external event.

00:13:07.180 | In this case, the event is the rotation of the Earth

00:13:09.980 | around the sun.

00:13:11.340 | There are other forms of entrainment,

00:13:13.560 | meaning the matching of your brain and body

00:13:16.040 | to things that are happening in your external environment.

00:13:18.800 | One particularly interesting example of this

00:13:20.820 | was published last year by Perik et al.

00:13:23.080 | in "Cell Report," "Cell Press Journal," excellent journal,

00:13:25.960 | showing that across the calendar year,

00:13:28.740 | the amount of testosterone and estrogen

00:13:31.280 | that human beings make varies,

00:13:33.740 | such that in longer days,

00:13:35.820 | they tend to make more testosterone and estrogen

00:13:38.280 | than in shorter days,

00:13:39.420 | and this was correlated with things like

00:13:41.800 | desire to seek out romantic partners

00:13:43.740 | or have romantic interactions with their existing partners,

00:13:47.140 | even aggression, although not violent aggression,

00:13:50.820 | but sense of kind of willingness to argue

00:13:52.980 | and to get into kind of combative states

00:13:56.180 | and overall energy and mood.

00:13:58.340 | This is something that had been hypothesized

00:13:59.980 | for a long time,

00:14:00.820 | but it had never really been cleanly demonstrated,

00:14:02.940 | and what they showed was that it's actually the skin

00:14:06.660 | that's taking information about the amount of light

00:14:08.960 | and converting it into these increases

00:14:10.940 | in testosterone and estrogen.

00:14:12.700 | Light exposure to the skin turns out about two hours a day.

00:14:17.500 | This was sunlight in this case to the upper body.

00:14:19.380 | These people weren't naked.

00:14:20.280 | They were wearing clothes, but their arms were exposed.

00:14:22.980 | Their upper back and neck and face were exposed.

00:14:25.140 | They were not wearing hats.

00:14:27.060 | Resulted in large increases,

00:14:29.840 | significant increases in testosterone and estrogen.

00:14:32.700 | Now, you could probably export a tool from that if you liked.

00:14:35.580 | That's not really what this podcast is about,

00:14:37.260 | but it's very clear that because the skin is acting

00:14:40.680 | as an endocrine organ, excuse me,

00:14:42.900 | as kind of a hormone influencing organ,

00:14:46.120 | that getting light on the skin, not just to the eyes,

00:14:49.080 | can influence our sense of wellbeing

00:14:51.580 | by these hormone pathways.

00:14:53.000 | And the threshold there, again,

00:14:54.600 | seemed to be about two hours a day.

00:14:55.960 | It doesn't have to be very bright outside.

00:14:57.660 | There can be cloud cover and so on.

00:14:59.320 | Many people will probably ask,

00:15:00.820 | will sunscreen inhibit this effect?

00:15:03.600 | And it doesn't appear that it does.

00:15:05.600 | Obviously, prioritize skin health and avoiding skin cancer.

00:15:09.960 | Sunscreen is kind of a controversial topic nowadays.

00:15:12.640 | Maybe the topic for another podcast episode at some point.

00:15:16.340 | But nonetheless, what the Perik et al study shows,

00:15:19.460 | and that's most relevant to today's podcast,

00:15:21.360 | is that we are entrained,

00:15:23.480 | we are matched to the external light-dark cycle.

00:15:26.400 | And as the day length changes, our hormones change.

00:15:29.600 | And we can override that with exposure to bright lights.

00:15:33.240 | People go sit on tanning beds.

00:15:35.360 | That's not a practice I particularly myself engage in,

00:15:38.440 | but there are a number of different ways

00:15:39.560 | that people can override these processes.

00:15:41.720 | But the point is very simple.

00:15:44.240 | The point is that our perception of time is both conscious,

00:15:49.240 | it's waiting, watching the clock tick down,

00:15:52.040 | and there are these slower, what we call oscillatory,

00:15:54.720 | meaning up and down repeatedly,

00:15:56.280 | slower oscillatory events related to day length

00:15:59.280 | that are influencing our hormones,

00:16:01.280 | like melatonin, testosterone, and estrogen,

00:16:03.160 | and therefore our mood, our outlook,

00:16:05.000 | and even our behavior.

00:16:06.400 | The next level of time or bin of time, as we say,

00:16:10.600 | that we are all entrained or matched to

00:16:14.920 | is the so-called circadian time cycle,

00:16:17.600 | which is 24-hour rhythm.

00:16:20.040 | This is perhaps the most powerful rhythm

00:16:23.560 | that we all contain and that none of us can escape from.

00:16:26.840 | We all have this circadian clock

00:16:30.900 | that resides over the roof of our mouth,

00:16:32.760 | the cells in that circadian clock fire,

00:16:35.600 | meaning they release chemicals into our brain and body

00:16:39.940 | on a very regular rhythm.

00:16:41.280 | So across the 24-hour cycle,

00:16:44.040 | they will be very active at some periods

00:16:46.320 | and less active at others.

00:16:48.220 | Not surprisingly, there are periods of every 24-hour cycle

00:16:52.240 | when we are very active and we tend to be alert

00:16:54.880 | and others when we are asleep.

00:16:57.040 | Now, I've talked a lot about circadian rhythms

00:16:58.800 | and sleep on this podcast previously,

00:17:01.080 | and so I don't want to repeat too much of that information

00:17:03.280 | in detail, but I'm just going to give a summary

00:17:05.100 | of how circadian entrainment works

00:17:07.120 | because I haven't really covered that

00:17:10.020 | in the context of time perception.

00:17:11.720 | We have the circadian clock.

00:17:15.140 | It oscillates, it goes up and down once every 24 hours

00:17:18.680 | and then repeats.

00:17:19.800 | Every cell of our body has a 24-hour oscillation

00:17:22.800 | in the expression of various genes.

00:17:24.800 | How that works is actually really simple,

00:17:26.720 | elegant, and interesting.

00:17:29.160 | DNA genes make RNA.

00:17:32.360 | RNA is converted into proteins.

00:17:34.520 | Every cell in our body has this beautiful 24-hour timer

00:17:39.880 | where a gene is expressed.

00:17:42.100 | And the important thing to understand about a given gene

00:17:45.600 | in this context is that that gene is inhibited,

00:17:49.220 | meaning it's reduced by a particular protein,

00:17:52.720 | by a little biological molecule in that cell.

00:17:55.800 | So the gene gets expressed when there's very little

00:17:59.400 | of that other molecule around.

00:18:01.320 | DNA then becomes RNA, RNA is translated into a protein,

00:18:06.320 | and that protein goes way, way up and the gene shuts down.

00:18:09.680 | But as that protein gets used up

00:18:12.400 | and its levels eventually drop low, low, low, low, low

00:18:14.620 | to zero, the gene cycle kicks in again

00:18:17.460 | and the gene gets expressed,

00:18:18.520 | the RNA gets expressed in the protein again.

00:18:21.260 | This all happens on a 24-hour cycle.

00:18:23.560 | So it's a little built-in timer in each and every one

00:18:25.860 | of our cells.

00:18:26.700 | And I didn't list off the genes,

00:18:27.880 | but for the aficionados out there,

00:18:29.240 | they go by names like per, for period, be, mal, clock,

00:18:32.400 | and all these different things.

00:18:33.220 | We call them the clock genes.

00:18:34.280 | And those clock genes regulate a number

00:18:35.860 | of different functions.

00:18:36.700 | So every cell in our body has a 24-hour cycle

00:18:39.360 | of gene and protein expression.

00:18:41.480 | And the earth rotates once every 24 hours.

00:18:44.820 | And the processes that are happening in every cell

00:18:47.560 | of our body are linked.

00:18:49.700 | They are entrained, as we say,

00:18:51.520 | to the outside light-dark cycle because morning sunlight,

00:18:56.420 | evening sunlight, and the lack of light

00:19:00.640 | in the middle of the night make sure that the changes,

00:19:05.160 | these oscillations that are occurring within the cells

00:19:07.780 | of our brain and body are matched

00:19:09.840 | to the outside light-dark cycle.

00:19:11.560 | And I want to go into all the details of how that happens,

00:19:13.640 | but there's some very simple tools that one can use

00:19:16.120 | to ensure that your entrainment,

00:19:18.620 | your circadian entrainment is precise.

00:19:21.580 | And I cannot emphasize enough how important it is

00:19:24.660 | that your circadian entrainment be precise.

00:19:27.540 | Why?

00:19:29.240 | Because disruptions in circadian entrainment

00:19:31.840 | cause huge health problems.

00:19:33.260 | They increase cancer risk.

00:19:34.780 | They increase obesity.

00:19:36.460 | They increase mental health issues.

00:19:38.820 | They decrease wound healing.

00:19:41.200 | They decrease physical and mental performance.

00:19:43.420 | They disrupt hormones.

00:19:44.740 | You want your cells to be linked to the circadian cycle

00:19:48.600 | that's outside you.

00:19:49.440 | And the circadian cycle outside you mainly consists

00:19:52.180 | of when there's sunlight and when there is not.

00:19:54.920 | And that's why the simple protocols to fall out

00:19:58.120 | of this whole discussion about circadian entrainment

00:20:00.580 | are the following.

00:20:01.680 | View 10 to 30 minutes of bright light, ideally sunlight,

00:20:04.720 | within an hour of waking,

00:20:06.400 | assuming that you're waking early in the day,

00:20:07.840 | especially you wake up early in the day,

00:20:09.600 | get outside, see sunlight.

00:20:10.840 | Do that again in the afternoon or around evening,

00:20:14.000 | 10 to 30 minutes, depending on how bright it is outside.

00:20:16.980 | Artificial lights throughout the day,

00:20:19.100 | or if you want to be awake and you wake up early

00:20:21.940 | and there's no sunlight outside,

00:20:23.540 | you can of course turn on artificial lights

00:20:25.380 | if you want to be awake,

00:20:26.280 | but basically you want as much bright light,

00:20:28.240 | ideally from sunlight,

00:20:29.600 | coming in through your eyes throughout the day.

00:20:31.640 | And then in the evening,

00:20:32.960 | you want as little bright light coming in through your eyes.

00:20:36.320 | I've said this over and over and over again on this podcast.

00:20:38.740 | There's always a lot of negotiations,

00:20:40.240 | but I want to make a few things clear.

00:20:41.940 | Try not to wear sunglasses.

00:20:43.120 | If you can do it safely,

00:20:44.240 | find to wear eyeglasses or contacts.

00:20:46.340 | That's not going to be a problem.

00:20:48.040 | The light viewing that you do

00:20:51.120 | and the avoidance of light at night,

00:20:53.140 | set the fundamental layer of your time perception.

00:20:58.140 | One of the best ways to disrupt your perception of time

00:21:02.440 | in the ways that we're going to talk about

00:21:03.920 | in the subsequent portions of the podcast

00:21:06.240 | is to disrupt your circadian clock.

00:21:07.960 | And that is not a good thing

00:21:09.440 | for a number of different reasons.

00:21:11.400 | There are other ways to so-called entrain

00:21:13.320 | your circadian clock.

00:21:14.280 | One of the best ways to do that

00:21:16.060 | is to engage in physical activity

00:21:18.960 | at fairly regular times of day.

00:21:20.680 | You don't have to do it every day,

00:21:21.740 | but if you're going to exercise,

00:21:23.360 | try and exercise at a fairly consistent time of day.

00:21:25.980 | Probably better to exercise than to not exercise,

00:21:29.040 | even if you have to move that time of day.

00:21:31.360 | But light, activity, and we'll talk about the third

00:21:34.720 | in a minute, food, are the major ways

00:21:36.920 | that you entrain your internal perception of time

00:21:40.140 | to the external events of the world,

00:21:43.640 | meaning that the turning of the earth

00:21:45.520 | and therefore the exposure to sunlight or not.

00:21:48.680 | So in addition to the sunlight viewing in the morning

00:21:52.840 | and throughout the day and avoiding bright light at night

00:21:54.720 | of any kind, not just blue light,

00:21:56.740 | trying to get your activity, your exercise at fairly regular

00:22:00.080 | within plus or minus two hours from each day to the next

00:22:04.000 | is going to have a very positive effect

00:22:05.880 | on so-called circadian entrainment.

00:22:08.080 | And also eating at fairly regular times.

00:22:10.760 | However, this is exciting.

00:22:13.200 | The data mainly point to the fact that you need to eat

00:22:15.680 | within more or less the same time window each day,

00:22:18.860 | not that you always need to eat your meals

00:22:20.900 | at exactly the same time.

00:22:22.720 | So you don't necessarily have to eat lunch at noon

00:22:26.000 | and a snack at four and dinner at eight

00:22:28.300 | in order to keep your circadian entrainment aligned or sharp.

00:22:33.300 | You could, for instance, have a small snack at noon

00:22:35.520 | and then eat at two and then have dinner at six

00:22:37.620 | and then a small snack at eight.

00:22:38.760 | It doesn't so much matter when the exact meals fall,

00:22:42.480 | so much as that they fall more or less

00:22:44.080 | within a consistent period or phase of each 24 hour cycle.

00:22:48.540 | What happens when this circadian clock

00:22:53.200 | starts getting disrupted?

00:22:54.320 | I mean, this is after all an episode about time perception.

00:22:57.160 | It's not an episode about circadian rhythms and entrainment.

00:23:00.340 | Well, there's a classic study by Ashoff done in 1985

00:23:05.340 | that's now been repeated many times

00:23:07.600 | where they had people go into environments

00:23:10.080 | where they didn't have clocks and they didn't have windows

00:23:12.480 | and they didn't have watches.

00:23:14.020 | And they were sometimes even in constant dark

00:23:15.740 | or constant light.

00:23:17.180 | And they evaluated how well people perceive

00:23:21.500 | the passage of time on shorter timescales.

00:23:24.200 | And what they found was really interesting.

00:23:25.760 | What they found is that people underestimate

00:23:28.160 | how long they were in these isolated environments.

00:23:30.160 | So after 42 days or so, they'd ask people,

00:23:33.300 | how long do you think you've been in here?

00:23:34.460 | And people would say 28 days or 36 days.

00:23:38.140 | They generally underestimated how long they had been

00:23:41.140 | in this very odd environment with no clocks or watches

00:23:43.820 | or exposure to sunlight or regular rhythms

00:23:46.540 | of artificial light.

00:23:48.300 | In addition, they found that their perception

00:23:51.740 | of shorter time intervals was also really disrupted.

00:23:55.380 | So if they asked them to measure off two minutes,

00:23:58.400 | normally people are pretty good

00:23:59.720 | at measuring off two minutes.

00:24:00.740 | People come within five to 15 seconds at most.

00:24:05.060 | If you kind of had to sit there and just wait,

00:24:07.460 | you have a pretty good idea of when two minutes is up,

00:24:09.300 | you say two minutes is up.

00:24:10.620 | Well, when people's circadian clocks

00:24:13.100 | or circadian entrainment, I should say, was disrupted,

00:24:16.060 | their perception of time measurement on shorter timescales

00:24:20.780 | of minutes or even seconds was greatly disrupted.

00:24:24.180 | And as we'll see in a couple of minutes,

00:24:25.700 | that actually causes great problems

00:24:28.380 | for how you contend with work,

00:24:30.260 | how you contend with challenges of different kinds.

00:24:33.060 | You want your circadian entrainment to be pretty locked in

00:24:37.900 | or pretty entrained to the outside light dark cycle

00:24:40.860 | so that your perception of time on shorter time intervals

00:24:45.060 | can be precise because the ability to perceive time

00:24:48.100 | accurately for the given task or given thing

00:24:51.220 | that you're involved in turns out to be one

00:24:53.340 | of the most fundamental ways that predicts how well

00:24:56.700 | or poorly you perform that thing or task.

00:24:59.580 | So we've talked about circadian entrainment,

00:25:02.460 | the matching of the cells and tissues

00:25:04.220 | and organs of our body to the 365 day journey

00:25:08.340 | that the earth takes around the sun each year.

00:25:11.320 | And we talked about circadian entrainment,

00:25:13.820 | the way that the 24 hour genetic and protein clocks

00:25:18.200 | of each and every one of our cells is matched

00:25:20.940 | to the rotation of the earth on its axis

00:25:23.700 | and the exposure or lack of exposure to the sun

00:25:28.180 | because of that rotation on its axis.

00:25:30.940 | Next, I'd like to talk about so-called

00:25:33.060 | ultradian entrainment.

00:25:34.780 | Ultradian rhythms are rhythms of about 90 minutes or so.

00:25:38.900 | And all of our existence is broken up

00:25:41.620 | into these 90 minute ultradian cycles.

00:25:44.180 | When you go to sleep at night,

00:25:45.420 | whether or not you sleep six hours or four hours

00:25:47.180 | or eight hours or 10 hours,

00:25:49.020 | that entire period of sleep is broken up

00:25:51.700 | into these 90 minute ultradian cycles.

00:25:54.260 | Early in the night, you tend to have more slow wave sleep.

00:25:56.260 | Later in the night, you tend to have more REM sleep.

00:25:58.320 | But nonetheless, your sleep is broken up

00:26:00.700 | into these 90 minute cycles.

00:26:02.400 | However, when you wake up in the morning,

00:26:04.660 | many of the things that you do are governed

00:26:07.780 | by these ultradian rhythms.

00:26:09.920 | For instance, if you were to work,

00:26:14.100 | meaning do math or try and learn a language

00:26:17.280 | or do physical work of any kind or work out,

00:26:19.740 | the 90 minute time block seems to be the one

00:26:23.780 | in which the brain can enter a state of focus

00:26:27.100 | and alertness and do hard work and focus, focus, focus.

00:26:29.640 | And then at about 90 minutes,

00:26:32.680 | there's a significant drop in your ability

00:26:35.100 | to engage in this mental or physical work.

00:26:38.060 | Now, everybody from the self-help literature

00:26:42.380 | to the business literature to the pop psychology literature

00:26:45.380 | has tried to leverage these ultradian cycles

00:26:48.020 | by saying if you're going to do something hard

00:26:50.700 | and you want to focus on it,

00:26:51.740 | limit it to 90 minutes or less.

00:26:53.100 | And I am one of those people

00:26:54.140 | who's also joined that conversation.

00:26:55.860 | And indeed I use 90 minute work cycles.

00:26:58.100 | And I think they are extremely powerful.

00:27:00.700 | One should never expect that you're going to drop

00:27:02.540 | immediately into a state of high focus at the beginning

00:27:05.660 | and then remain there for 90 minutes.

00:27:07.620 | We all struggle to varying degrees to achieve focus

00:27:10.860 | and motivation and drive within those 90 minute cycles.

00:27:13.580 | But it is true, meaning there is ample literature

00:27:17.500 | to support the idea that after about 90 minutes,

00:27:21.720 | we tend to go into a state of less ability to focus.

00:27:25.440 | So while this isn't time perception per se,

00:27:28.900 | it is again, an example of entrainment.

00:27:31.760 | What are we in training to, right?

00:27:34.180 | Just because we can focus for 90 minutes

00:27:36.020 | and then not so well at 100 minutes or 120 minutes,

00:27:39.560 | what are we in training to?

00:27:40.640 | Well, what you're in training to

00:27:41.780 | is the release of particular neurochemicals,

00:27:44.800 | in this case, acetylcholine and dopamine

00:27:47.180 | that allow your brain to focus

00:27:49.140 | for particular periods of time, 90 minutes or so.

00:27:52.240 | And after about 90 minutes or so,

00:27:55.500 | the amount of those chemicals that can be released

00:27:57.620 | tends to drop very low,

00:27:58.600 | which is why your ability to focus becomes diminished.

00:28:02.760 | If one would like to explore more about the kind of backbone

00:28:05.600 | and basis of these ultradian rhythms,

00:28:08.640 | it goes by a different name.

00:28:09.880 | This was originally called the basic rest activity cycle.

00:28:13.960 | This was proposed many years ago by Nathaniel Kleitman.

00:28:17.620 | It was established to be true within sleep states,

00:28:20.940 | as I mentioned before.

00:28:21.920 | Then it was debated for a long time

00:28:23.440 | whether or not these 90-minute cycles

00:28:25.440 | also control our ability to focus and perform work

00:28:29.000 | in wakeful states, and it turns out that they do.

00:28:31.000 | Now there's a lot of literature to support that.

00:28:33.800 | I always get the question,

00:28:34.840 | how do you know when the 90-minute cycle begins?

00:28:37.160 | In other words, let's say you wake up at 8 a.m.

00:28:40.200 | and you just finished a 90-minute sleep cycle.

00:28:42.340 | Does that mean that your next 90-minute cycle

00:28:45.100 | where you could do work begins right at 801?

00:28:47.680 | No.

00:28:48.740 | The interesting thing about these basic rest activity cycles,

00:28:51.720 | these ultradian rhythms,

00:28:53.040 | is that you can initiate them whenever you want.

00:28:56.100 | This is not like a circadian rhythm,

00:28:57.820 | which is a hardwired, unerring signal of 24 hours.

00:29:02.820 | The ultradian rhythms that occur during sleep

00:29:06.220 | are hardwired, unerring.

00:29:08.820 | You don't get the option of making your sleep cycles

00:29:11.200 | at 120 minutes or five minutes.

00:29:13.480 | You don't get that option.

00:29:15.640 | But if you decide that you want to apply

00:29:17.700 | ultradian rhythms to work and performance,

00:29:20.140 | you can set a clock and decide,

00:29:21.940 | okay, now the focus begins.

00:29:24.240 | Now the work begins, and this 90-minute cycle

00:29:26.880 | is the period in which I'm going to do work.

00:29:28.660 | And I actually do this.

00:29:30.240 | Mid-morning and sometimes twice a day,

00:29:32.000 | I do a 90-minute cycle where I limit all distraction

00:29:35.720 | as much as possible, put away my phone,

00:29:37.340 | often turn off the internet as well.

00:29:38.760 | I talked about this in an episode

00:29:40.540 | on kind of an optimal workday, at least for me,

00:29:44.520 | just to give an example of how this might work.

00:29:46.700 | But I want to emphasize again

00:29:48.860 | that these ultradian rhythms are ones that you set.

00:29:52.040 | So you decide I'm going to work for 90 minutes.

00:29:54.600 | What you can't negotiate, however,

00:29:56.640 | is that at about 100 minutes or 120 minutes,

00:29:59.760 | no matter who you are,

00:30:00.720 | you're going to see a diminishment in performance.

00:30:03.680 | You're not going to focus as well.

00:30:05.900 | And that's, again, because of the way

00:30:07.260 | that these 90-minute cycles are linked

00:30:09.260 | to the ability of the neurons

00:30:10.720 | that release acetylcholine and dopamine

00:30:12.680 | and to some extent norepinephrine,

00:30:14.080 | the things that give us narrow focus, motivation, and drive,

00:30:17.020 | the way that these 90-minute cycles

00:30:18.800 | are involved in those circuits.

00:30:21.920 | After about 90 minutes,

00:30:23.040 | those circuits are far less willing to engage,

00:30:25.660 | and therefore it's much harder

00:30:27.440 | to continue to focus to a high degree.

00:30:30.640 | Some people like to do multiple 90-minute cycles

00:30:32.960 | per day of focus.

00:30:33.840 | In that case, you need to separate them out.

00:30:35.580 | You can't do one 90-minute cycle,

00:30:37.220 | then go right into another 90-minute cycle then.

00:30:39.200 | Go down to the 90-minute cycle.

00:30:40.160 | You can't cheat these circuits related

00:30:42.360 | to acetylcholine and dopamine and norepinephrine,

00:30:45.040 | unfortunately.

00:30:46.240 | I suggest that people do no more than three,

00:30:49.180 | and ideally it would be two or just one

00:30:52.260 | of these 90-minute cycles.

00:30:53.340 | Why did I say ideally?

00:30:54.440 | Well, they are very taxing.

00:30:56.580 | You are in a very narrow tunnel of focus.

00:30:59.320 | So for me, I can do one mid-morning,

00:31:01.960 | and I can probably do another one in the afternoon.

00:31:04.240 | This is not the kind of work that's like checking email

00:31:06.360 | or text messaging or social media.

00:31:07.840 | This is very focused, hard work,

00:31:09.800 | and it's working on hard problems of various kinds,

00:31:12.680 | and this will be different for everybody.

00:31:14.720 | So I recommend that they be spaced

00:31:16.240 | by at least two to four hours,

00:31:18.600 | and most people probably won't be able

00:31:20.640 | to handle more than two per day.

00:31:22.900 | There are probably some mutants out there

00:31:24.240 | that could do three or four, but that's exceedingly rare.

00:31:27.220 | I think even one a day is going to feel

00:31:29.200 | like a significant mental investment,

00:31:31.480 | and afterwards you're going to feel pretty taxed.

00:31:33.820 | So now we've talked about circannual,

00:31:35.780 | circadian, and ultradian rhythms,

00:31:39.020 | but we haven't really talked about time perception per se.

00:31:42.360 | We've mainly talked about the subconscious,

00:31:44.900 | slow oscillatory ways in which we are entrained

00:31:48.260 | or matched to the year or to the day,

00:31:50.800 | and these ultradian cycles that we can impose on our work

00:31:55.360 | and that we can leverage toward more focus if we like.

00:31:59.080 | But what about the actual perception of time?

00:32:02.020 | What actually controls how fast or how slowly

00:32:05.760 | we perceive time going by?

00:32:08.260 | There are basically three forms of time perception

00:32:11.040 | that we should all be aware of.

00:32:12.800 | One is our perception of the passage of time in the present,

00:32:15.720 | how quickly or slowly things seem to be happening for us.

00:32:19.480 | This is kind of like an interval timer, ticking off time,

00:32:22.620 | tick, tick, tick, tick, tick, tick.

00:32:24.360 | It's either fine slicing like that or tick, tick, tick.

00:32:29.360 | We have interval timers.

00:32:31.440 | I'll discuss the basis of those interval timers.

00:32:33.720 | We also engage in what's called prospective timing,

00:32:36.420 | which is like a stopwatch,

00:32:37.660 | measuring off things as they go forward.

00:32:40.220 | That might sound a little bit like what I just described,

00:32:42.140 | but it's actually a little bit different.

00:32:44.240 | For instance, if I told you to start measuring off

00:32:48.840 | a two-minute time interval into the future,

00:32:51.800 | you could do that pretty well.

00:32:53.820 | But if I told you you had to measure

00:32:55.960 | a five-minute time interval into the future

00:32:58.360 | and you couldn't use any clocks or watches or your phone

00:33:00.760 | or anything like that, you would have to set the tick marks.

00:33:05.320 | You would have to decide how many times

00:33:08.080 | you were going to count off

00:33:09.240 | during that five-minute time block.

00:33:11.920 | There's also retrospective time,

00:33:14.060 | which is how you measure off time in the past.

00:33:17.680 | So if I say, "Last week, I know you went to the park.

00:33:21.740 | You did some things with friends.

00:33:23.040 | You went out in the evening."

00:33:25.320 | How long was it between lunch

00:33:28.000 | and when you went to dinner with friends?

00:33:29.300 | You probably then go, "Okay, well, I remember.

00:33:30.880 | I went to dinner at seven and we had lunch right around two."

00:33:33.840 | You're using memory to reconstruct

00:33:36.760 | certain sets of events in the past

00:33:38.560 | and get a sense of their relative positioning within time.

00:33:42.360 | So we have retrospective,

00:33:43.760 | current time interval measurements,

00:33:45.280 | and then a prospective time measurement into the future.

00:33:48.280 | The beauty of time perception in the human nervous system

00:33:54.660 | is that it boils down to a couple of simple molecules

00:33:59.140 | that govern whether or not we are fine slicing time

00:34:03.160 | or whether or not we are batching time in larger bins.

00:34:06.360 | Those molecules go by names that maybe you've heard,

00:34:09.960 | things like dopamine and norepinephrine,

00:34:12.160 | neuromodulators, called neuromodulators,

00:34:14.280 | because they modulate,

00:34:15.240 | they change the way that other neural circuits work.

00:34:18.600 | Also things like serotonin.

00:34:21.200 | Serotonin is released from a different site in the brain

00:34:23.660 | than dopamine and norepinephrine is,

00:34:25.880 | and has a different effect on time perception.

00:34:29.080 | So just to give you an example

00:34:30.400 | of how things like dopamine and serotonin

00:34:33.400 | can modulate our perception of time,

00:34:36.320 | I want to focus on a little bit of literature

00:34:38.940 | that now has been done, fortunately, in animals and humans,

00:34:41.860 | and which essentially shows that the more dopamine

00:34:46.180 | that's released into our brain,

00:34:49.420 | the more we tend to overestimate the amount of time

00:34:52.580 | that has just passed.

00:34:54.180 | Let me repeat that.

00:34:55.040 | The more dopamine that is released into our brain,

00:34:58.440 | the more we tend to overestimate how much time has passed.

00:35:02.020 | These experiments are very straightforward, excuse me,

00:35:04.960 | and they're very objective, which is really nice,

00:35:07.000 | which is you can give people or an animal a drug

00:35:10.560 | that increases the amount of dopamine,

00:35:12.780 | and then ask them to measure off

00:35:15.240 | without any measurement device, like a watch or a clock,

00:35:18.440 | when one minute has passed.

00:35:20.860 | As dopamine levels rise in the brain,

00:35:23.520 | people tend to think that the minute is up before a minute.

00:35:28.520 | So at the 38-second mark, they'll say,

00:35:31.080 | "Okay, I think a minute is up."

00:35:32.160 | So they've overestimated how much time has passed, okay?

00:35:35.960 | The higher the level of dopamine,

00:35:37.560 | the more people tend to overestimate.

00:35:39.680 | Now, it's also true that norepinephrine,

00:35:43.140 | also called noradrenaline, plays a role,

00:35:45.400 | and its role is very similar to that of dopamine.

00:35:47.960 | And that's because norepinephrine and dopamine

00:35:49.880 | are close cousins.

00:35:51.000 | As some of you may recall that they are actually manufactured

00:35:55.080 | from one another, okay?

00:35:56.400 | So dopamine can actually make epinephrine

00:35:59.480 | and norepinephrine.

00:36:00.360 | Biochemically, there's a cascade in which dopamine

00:36:03.960 | can be made into norepinephrine and epinephrine,

00:36:06.400 | which is remarkable.

00:36:07.960 | How does having elevated levels of dopamine

00:36:09.960 | and norepinephrine cause one to overestimate

00:36:12.720 | how much time has passed?

00:36:14.540 | Well, it does it because of the way

00:36:16.800 | that it causes fine slicing of your time bins.

00:36:21.360 | So fine slicing of time bins is like increasing

00:36:24.400 | the frame rate on your camera, right?

00:36:27.220 | Slow motion is achieved in movies and elsewhere

00:36:32.220 | by increasing the frame rate.

00:36:34.400 | So if you take a movie at 30 frames per second and watch it,

00:36:39.200 | it will appear to have a certain speed, right?

00:36:41.160 | 'Cause those are just snapshots, 30 frames per second.

00:36:44.700 | In contrast, if you took that same movie

00:36:47.220 | at 4,000 frames per second, you are fine slicing

00:36:50.500 | and you're going to see every little detail.

00:36:51.780 | And as you play each one of those frames,

00:36:53.780 | it's going to look like it moved slower, okay?

00:36:56.980 | Whatever, so the kind of jump shot in basketball

00:36:59.540 | that's done slowly, any slow motion is the consequence

00:37:03.060 | of higher frame rate.

00:37:04.780 | So dopamine and norepinephrine increase frame rate.

00:37:09.340 | And as a consequence, they tend to lead us

00:37:12.420 | to overestimate the amount of time that's passed.

00:37:15.520 | Conversely, the neuromodulator serotonin causes people

00:37:21.100 | to underestimate the amount of time that's passed.

00:37:24.560 | So they've done these experiments.

00:37:26.220 | They actually have done these experiments using in humans

00:37:29.220 | with drugs that increase serotonin.

00:37:30.820 | They've also done them with cannabis,

00:37:32.620 | which increases serotonin among other things,

00:37:34.820 | including the cannabinoid receptor activation.

00:37:38.940 | And when people have elevated levels of 5-HT

00:37:43.220 | or whether or not they've ingested cannabis,

00:37:44.980 | they tend to underestimate how much time has passed.

00:37:47.520 | You do the equivalent experiment.

00:37:48.660 | You tell people that they have to guess

00:37:51.060 | or tell you when five minutes, for instance, has passed,

00:37:54.380 | just to use five minutes as an example this time,

00:37:56.500 | and generally they will miss the five-minute mark.

00:37:59.460 | They will think, they'll let six minutes pass

00:38:01.900 | and it looks like it was five minutes

00:38:03.380 | when they've underestimated how much time has passed.

00:38:06.140 | And that's because serotonin and some of the related

00:38:09.740 | molecules in the brain tend to lead to slower frame rates.

00:38:14.740 | They take the frame rate from, in the example I used before,

00:38:17.880 | from 4,000 frames per second down to say 20 frames per second

00:38:22.300 | So this is very interesting.

00:38:24.320 | It's interesting in terms of how pharmacology can be used

00:38:28.400 | to adjust time perception, but it's also interesting

00:38:31.160 | in the context of that circadian rhythm.

00:38:34.260 | There's some emerging evidence that throughout

00:38:36.660 | the 24-hour cycle, there are robust changes

00:38:39.900 | in the amount of dopamine, norepinephrine, and serotonin

00:38:42.380 | that are present in the brain and bloodstream and body,

00:38:45.680 | depending on time of day within the circadian cycle.

00:38:50.680 | Now I'm not talking about during sleep.

00:38:53.700 | During sleep, there are definitely variations

00:38:55.620 | in things like dopamine, norepinephrine, and serotonin.

00:38:57.700 | I talked about that in the episodes on sleep.

00:39:00.060 | Here I'm just talking about the role of these molecules

00:39:03.360 | in time perception during wakefulness.

00:39:05.900 | So much of the evidence points to the fact

00:39:09.100 | that in the first half of the day,

00:39:11.020 | approximate first half of the day,

00:39:12.940 | dopamine and norepinephrine are elevated in the brain,

00:39:15.580 | body, and bloodstream much more than is serotonin.

00:39:19.860 | And that in the second half of the day,

00:39:21.340 | and in particular towards evening and nighttime,

00:39:23.100 | serotonin levels are going up.

00:39:25.500 | I think that's fairly well-established now.

00:39:27.800 | What that means based on what we just discussed

00:39:30.440 | about the role of dopamine, norepinephrine, and serotonin

00:39:32.780 | in setting the frame rate of time perception

00:39:36.220 | is that our perception of the passage of time

00:39:38.940 | will be very different in the early part of the day

00:39:41.360 | and in the latter half of the day.

00:39:43.360 | And there's starting to be some evidence to support this,

00:39:46.060 | that early in the day,

00:39:47.980 | people tend to overestimate how much time has passed.

00:39:51.080 | And later in the day,

00:39:51.920 | they tend to underestimate how much time has passed.

00:39:54.020 | And this is independent of taking any kind of substance

00:39:56.200 | that would increase or decrease dopamine or serotonin.

00:39:59.200 | Now, this is important in terms of how one thinks

00:40:01.960 | about structuring their day,

00:40:03.160 | because I know many people are thinking about

00:40:05.200 | the various tasks that they need to do

00:40:07.000 | throughout their day.

00:40:08.760 | Many, or I should say all of the literature at least

00:40:12.220 | that I can find on productivity and things of that sort

00:40:15.400 | point to the idea that we should be doing the hardest task,

00:40:18.860 | the thing that we want to do the least

00:40:20.460 | or the most important task early in the day

00:40:23.440 | as a kind of a psychological tool for getting it done

00:40:26.780 | and feeling as if we accomplished something.

00:40:28.680 | And I think that's an excellent protocol, frankly.

00:40:31.760 | But I'm not sure it's an excellent protocol

00:40:33.520 | because of the way that we sense accomplishment,

00:40:37.340 | or at least it's not only an excellent protocol

00:40:39.760 | because of the way that we sense accomplishment.

00:40:42.040 | Another reason to move something that's very hard

00:40:44.880 | into the early part of the day

00:40:46.880 | is that if indeed the dopaminergic and noradrenergic circuits

00:40:51.880 | are more active at that time,

00:40:54.580 | we are actually in a better position cognitively

00:40:57.880 | to parse that hard problem

00:40:59.840 | because of the way that we are able to fine slice

00:41:03.480 | our perception of time

00:41:04.720 | and fine slice all the perceptual events outside us.

00:41:07.840 | So what I'm really saying is that early in the day

00:41:09.960 | you are a much more high resolution camera, so to speak,

00:41:13.900 | than you are later in the day.

00:41:15.660 | Now, different types of tasks and different types of things

00:41:18.840 | require different frame rates

00:41:21.000 | or different ways of perceiving time.

00:41:23.160 | And indeed this also lends itself to a tool

00:41:25.960 | whereby for activities that involve more kind of

00:41:30.040 | creative thinking that aren't as constrained

00:41:32.920 | by particular answers or outcomes,

00:41:35.480 | and in which we need to kind of blend different aspects

00:41:39.120 | of our memory, different aspects of task utilization,

00:41:43.720 | in other words, for creative works, for brainstorming,

00:41:47.000 | for things that are a bit more fluid, so to speak,

00:41:49.900 | the more serotonergic second half of the day,

00:41:53.400 | and because of the way the serotonergic

00:41:55.160 | second half of the day lends itself to our time perception,

00:41:58.440 | may actually be more beneficial for those sorts of tasks.

00:42:01.520 | And I'll put a reference to a couple of the studies

00:42:03.720 | that point to this idea

00:42:05.240 | that in these higher dopaminergic states,

00:42:08.340 | we are better at doing certain sorts of tasks,

00:42:11.800 | and in these more serotonergic states,

00:42:13.520 | we're better at doing other sorts of tasks,

00:42:15.840 | and how the dopamine tends to be earlier in the day

00:42:18.920 | and the serotonin later in the day, so to speak,

00:42:21.200 | these are broad, I'm painting with broad strokes here,

00:42:23.800 | but I think these lend themselves

00:42:25.280 | to some really excellent tools,

00:42:26.720 | because I think we all understand the value

00:42:29.020 | of doing something that's hard or challenging

00:42:30.880 | early in the day, but we should ask ourselves,

00:42:32.880 | hard or challenging how?

00:42:34.580 | What does that task actually really require

00:42:36.960 | in terms of time perception?

00:42:38.600 | Some people might appreciate some examples

00:42:40.240 | of how this might work.

00:42:41.360 | Basically what I'm saying is if you are doing work

00:42:43.760 | that involves adhering to some rigid rules,

00:42:47.000 | so math or a recipe or execution of musical scales

00:42:51.800 | or physical skills or accounting

00:42:55.420 | or something that requires a lot of precision

00:42:57.560 | where there's a right and wrong answer and it's hard,

00:43:00.960 | I would suggest that you do that

00:43:02.120 | in the early part of the day

00:43:03.300 | because of the way that dopamine and norepinephrine

00:43:05.840 | impact time perception.

00:43:08.400 | You are literally better at slicing up time.

00:43:11.680 | You are a higher resolution brain during those times,

00:43:15.040 | and so that's going to lend itself better

00:43:17.000 | to events and demands that require high resolution,

00:43:20.740 | whereas in the afternoon,

00:43:22.600 | in this more of what I'm calling serotonergic state,

00:43:25.200 | that's when you're going to be better at brainstorming

00:43:27.360 | and creative works where there's some flexibility

00:43:30.120 | in terms of how you're batching time and perceiving time,

00:43:33.200 | and there isn't so much rigid oversight

00:43:36.220 | of a right or wrong answer.

00:43:37.920 | And as an aside to support what I said,

00:43:40.280 | but also to take us back to this critical role

00:43:43.400 | of the circadian rhythm, there is a lot of evidence

00:43:46.840 | that when one's sleep is disrupted,

00:43:49.240 | when sleep is either too short or is fragmented

00:43:52.020 | or is not of high enough quality for enough days,

00:43:55.280 | one of the first things to happen

00:43:57.360 | is that there is a dysregulation

00:43:59.680 | of these dopaminergic, neurodegenergic,

00:44:02.240 | and serotonergic states throughout the day.

00:44:04.020 | They get kind of mish-mashed up.

00:44:07.780 | It's not that they're a total mess,

00:44:09.460 | but they aren't as cleanly defined.

00:44:12.280 | And I think this is one of the reasons

00:44:13.720 | why when we haven't slept well or we haven't slept enough,

00:44:17.080 | we tend to feel a little off, like we can't concentrate.

00:44:19.680 | Part of that lack of concentration is due to other things.

00:44:22.340 | But part of that concentration could be due to the fact

00:44:24.260 | that our sense of the passage of time is disrupted.

00:44:27.200 | So there seems to be some value

00:44:28.560 | in keeping the dopaminergic, neurodegenergic state

00:44:32.380 | kind of limited to the early part of the day

00:44:34.200 | and the serotonergic state, as we're calling it,

00:44:36.360 | kind of pushed towards the second half of the day.

00:44:38.840 | Now, there is a version of how dopamine and norepinephrine

00:44:41.820 | can impact our perception of the passage of time

00:44:44.440 | in ways that can be very disruptive or even maladaptive.

00:44:48.960 | And the best example that I'm aware of is trauma.

00:44:52.960 | Many people who have been in car accidents

00:44:55.640 | or who have experienced some other form of major trauma

00:44:58.960 | do what's called overclocking.

00:45:02.640 | Overclocking is when levels of dopamine and norepinephrine

00:45:07.440 | increase so much during a particular event.

00:45:10.440 | Our level of alertness has increased so much

00:45:13.920 | during a given event that we find slice.

00:45:18.080 | In other words, the frame rate is increased so much so

00:45:21.840 | that we perceive things as happening in ultra slow motion.

00:45:25.960 | Now, that might not seem like a bad thing overall,

00:45:30.120 | but the problem with overclocking is the way

00:45:33.800 | in which that information gets stamped down

00:45:35.960 | into the memory system.

00:45:37.640 | So the memory system, which involves areas of the brain

00:45:40.740 | like the hippocampus, but also the neocortex,

00:45:43.540 | is basically a space-time recorder.

00:45:46.420 | What do I mean by space-time recorder?

00:45:48.120 | Well, your nervous system, of course,

00:45:50.400 | is housed in the darkness of your skull.

00:45:52.980 | It doesn't have a whole lot of information

00:45:54.460 | about the outside world except light coming in

00:45:56.320 | through the eyes and whatever happens to hit our ears

00:45:58.620 | in terms of sound waves and skin and so forth.

00:46:02.280 | So it has to take all those neural signals

00:46:04.080 | and it has to create a record of what happened.

00:46:07.400 | Now, it doesn't create a record of everything that happened,

00:46:09.640 | but car accidents and trauma and things of that sort

00:46:13.140 | oftentimes are stamped down

00:46:14.480 | into our record of what happened.

00:46:17.320 | And what gets stamped down,

00:46:19.720 | what we actually mean by the phrase stamped down,

00:46:22.240 | is that the precise firing of the sequence of neurons

00:46:25.760 | that reflected some event,

00:46:28.000 | so let's say I'm in a car accident,

00:46:29.880 | certain neurons are firing because of the flipping

00:46:32.240 | of the car or there's screams or there's blood

00:46:35.320 | or things of that sort.

00:46:37.380 | All of that neural activity gets repeated

00:46:42.240 | in the hippocampus and then the sequence of the firing

00:46:46.160 | of those neurons is also remembered.

00:46:47.860 | So it's not just that neuron one, two, three, four fired

00:46:51.160 | in that sequence, it's also that neuron one, two, three, four

00:46:53.940 | fired at a particular rate.

00:46:55.420 | So it would be one, two, three, four during the actual event

00:46:57.920 | and then the memory is stored as firing of those neurons

00:47:01.000 | as one, two, three, four, right?

00:47:02.360 | If during the event it was one, two, three, four

00:47:05.020 | at that rate, the storage of the memory

00:47:07.820 | is not going to be one, two, three, four, okay?

00:47:12.200 | In other words, there's both a space code as we say,

00:47:15.680 | meaning the particular neurons that fire is important

00:47:18.640 | and there's a rate code, how quickly those neurons fire

00:47:22.200 | or the relative firing, the timing of the firing

00:47:24.920 | of those neurons is also part of the memory.

00:47:26.880 | This affords our memory system tremendous flexibility.

00:47:29.280 | What it means is that you can take the same set of neurons

00:47:31.760 | in the hippocampus and stamp down many, many more memories

00:47:35.560 | because all you have to do is use a match

00:47:39.540 | of the different rates of the different neurons

00:47:41.800 | that were firing in order to set that code, right?

00:47:44.920 | Otherwise, if you needed a different set of neurons

00:47:46.860 | for every memory, you need an enormous hippocampus,

00:47:49.000 | you need an enormous head.

00:47:50.180 | So I think you get the basic idea.

00:47:52.440 | Overclocking is a case in which the frame rate is so high

00:47:56.960 | that a memory gets stamped down

00:47:59.140 | and people have a very hard time shaking that memory

00:48:01.560 | and the emotions associated with that memory.

00:48:03.840 | And it's not the topic of today's conversation

00:48:06.040 | but we will cover trauma in a future episode in detail

00:48:09.080 | but many of the treatments for trauma, EMDR,

00:48:13.320 | nowadays there's a lot of excitement also

00:48:14.840 | about ketamine therapies, exposure therapies,

00:48:18.900 | like cognitive behavioral therapies,

00:48:20.740 | involve not just trying to reduce the amount

00:48:23.240 | of emotion associated with a memory

00:48:25.240 | but also a deliberate speeding up

00:48:28.320 | or slowing down of that memory.

00:48:30.360 | In other words, trying to allow the person

00:48:32.880 | who experienced the trauma to take control

00:48:34.780 | of the rate of the experience in their memory,

00:48:38.200 | not just whether or not the memory happened at all.

00:48:41.040 | In fact, one of the first things that trauma victims learn

00:48:44.640 | is that they aren't going to forget what happened.

00:48:47.340 | What's eventually going to happen,

00:48:48.840 | ideally with good treatment,

00:48:50.600 | is that the emotional weight of the experience

00:48:53.760 | will eventually be divorced

00:48:56.040 | from the memory of the experience.

00:48:57.960 | And that's done again by trying to reduce

00:49:00.360 | the amount of emotional activation

00:49:02.240 | during the recall of that experience.

00:49:03.880 | And one of the best ways to do that

00:49:05.600 | is to alter the rate of the memory playback.

00:49:10.020 | In other words, taking that firing of neurons

00:49:12.020 | that might've been one, two, three, four,

00:49:14.240 | again, it would be much more complicated,

00:49:15.880 | but one, two, three, four for the car crash,

00:49:17.720 | and getting the memory to play back at a rate of one,

00:49:21.520 | two, three, four, or even one, two, three, four,

00:49:25.800 | one, two, three, four.

00:49:27.360 | In other words, allowing the person

00:49:29.920 | or instructing the person to take control

00:49:32.640 | of the rate of the playback.

00:49:33.920 | And in that way, there seems to be

00:49:35.800 | still yet unknown mechanism

00:49:37.560 | by which people can uncouple some of the emotional weight

00:49:41.700 | that's associated with that memory.

00:49:43.480 | So overclocking is a kind of extreme example

00:49:48.400 | of where the dopaminergic and the noradrenergic system

00:49:51.120 | is ramped up so high that people have this,

00:49:54.280 | unfortunately, what seems like indelible mark

00:49:56.640 | in their brain of a particular event.

00:49:58.400 | But again, trauma treatment is designed

00:50:00.000 | to uncouple the emotional load of that event.

00:50:02.560 | Some of you are probably saying, why dopamine during trauma?

00:50:05.880 | I thought dopamine was the feel-good molecule.

00:50:08.320 | Well, in reality,

00:50:10.480 | dopamine is not necessarily a molecule of reward,

00:50:13.120 | it's a molecule of motivation, pursuit, and drive.

00:50:16.080 | And because of the close relationship

00:50:17.800 | between dopamine and norepinephrine,

00:50:19.520 | oftentimes they are co-released.

00:50:21.560 | So whether or not dopamine is released during car crashes

00:50:25.000 | or other forms of trauma, we don't know.

00:50:27.140 | But what we do know is that both the dopamine system

00:50:29.620 | and noradrenergic system, when we say noradrenergic,

00:50:32.200 | when we mean norepinephrine,

00:50:33.260 | those systems are greatly increased

00:50:35.200 | anytime there's a heightened state of arousal.

00:50:37.600 | And arousal can have negative valence,

00:50:39.880 | like meaning associated with an event that we really hate,

00:50:43.160 | that we would prefer not to be involved in,

00:50:45.080 | or it can have positive valence.

00:50:47.040 | But dopamine and norepinephrine

00:50:48.640 | are kind of the common hallmark

00:50:50.680 | of all things of elevated arousal.

00:50:53.440 | And so that's why we see evidence for dopamine

00:50:56.400 | being associated with these changes in time perception,

00:50:59.200 | both for positive events and for negative events.

00:51:03.020 | There's a very interesting relationship

00:51:04.880 | between arousal, dopamine, time perception, and blinking.

00:51:09.880 | And this is all supported by a really interesting paper.

00:51:13.360 | First author Terhune is the last name,

00:51:15.520 | T-E-R-H-U-N-E, is published in Current Biology,

00:51:18.360 | Cell Press Journal, excellent journal.

00:51:20.240 | The title of the paper is

00:51:21.080 | "Time Dilates After Spontaneous Blinking."

00:51:24.100 | So heightened states of arousal

00:51:25.360 | are associated with heightened levels of dopamine.

00:51:27.220 | You now know that dopamine leads

00:51:29.180 | to a kind of fine slicing of time.

00:51:32.440 | And one of the ways that we fine slice time is by blinking.

00:51:36.240 | You know, we think of blinking

00:51:37.180 | as just a thing to like lubricate our eyes

00:51:39.040 | or to limit the amount of light coming into our eyes,

00:51:41.440 | but it's a shutter on our experience.

00:51:44.020 | So much of the information

00:51:45.500 | that coming into the brain through our eyes

00:51:46.980 | impacts our attention.

00:51:47.980 | I've said it before on this podcast

00:51:49.500 | that cognitive attention follows visual attention,

00:51:51.760 | at least for sighted individuals.

00:51:53.700 | Well, it turns out that dopamine and increases in dopamine

00:51:57.920 | are associated with increases in spontaneous blink rate.

00:52:01.320 | So the more aroused we are, the more awake we are.

00:52:05.000 | There are a number of effects,

00:52:05.840 | pupils dilate, heart rate increases, et cetera,

00:52:08.080 | but also blink rate increases.

00:52:09.980 | And every time we blink, this study cleanly shows,

00:52:13.240 | we shift our perception of time,

00:52:16.040 | leading to, as I mentioned before, overestimations of time.

00:52:20.280 | So it seems as though in some way,

00:52:22.520 | blink rate is actually related to frame rate.

00:52:25.700 | And so this is very, very interesting.

00:52:27.840 | And the way that you could think about leveraging this

00:52:30.160 | would be if you wanted to actually slow down

00:52:33.960 | your perception of time, you would blink less.

00:52:36.880 | And if you want to speed up your perception of time,

00:52:39.440 | you would blink more.

00:52:40.440 | Now you'd have to think of a scenario

00:52:42.200 | in which that would be useful to you.

00:52:44.200 | Obviously, if you're going to blink,

00:52:45.100 | you're going to miss things as well.

00:52:46.900 | But I think it's a very interesting parameter

00:52:49.780 | of our visual attention as it relates to time perception,

00:52:53.140 | because what it really speaks to

00:52:54.700 | is that these neuromodulators like dopamine or serotonin

00:52:57.820 | that adjust frame rate,

00:52:58.780 | they're not doing it through some magical mechanism.

00:53:01.300 | In fact, there's no single brain area

00:53:03.500 | that we can say controls time perception.

00:53:06.140 | I haven't said today, oh, you know, it's the striatum.

00:53:08.860 | Well, it involves the striatum,

00:53:10.440 | but I'm not going to say, for instance,

00:53:12.220 | oh, it's the cerebellum.

00:53:13.340 | The cerebellum is definitely involved

00:53:14.940 | in timing of movement, something for a future podcast,

00:53:18.600 | but time perception is what we call a distributed phenomenon.

00:53:22.360 | It's a network of areas in the brain working together,

00:53:25.420 | but dopamine in the way that it relates

00:53:28.080 | to the shuttering of your eyes

00:53:30.940 | seems to be controlling the frame rate on your experience.

00:53:34.360 | Numerous times on this podcast,

00:53:35.780 | I've talked about cold exposure,

00:53:37.460 | and nowadays there's a lot of interest

00:53:39.240 | in things like cold showers, ice baths,

00:53:42.320 | submersion in cold water tanks,

00:53:45.140 | and lakes and oceans and things of that sort.

00:53:47.860 | There are a lot of different positive effects

00:53:49.780 | of cold exposure.

00:53:51.400 | Provided it's done properly,

00:53:52.500 | it can lead to increases in metabolism,

00:53:54.240 | brown fat stores, which are the good fat stores

00:53:56.220 | that you want.

00:53:57.060 | They're sort of like a furnace

00:53:58.500 | that allow you to heat yourself up,

00:53:59.700 | stay warm in cold environments to reduce inflammation,

00:54:03.740 | to increase resilience and so forth.

00:54:05.540 | There's a study published

00:54:07.780 | in the European Journal of Physiology

00:54:09.300 | showing that cold exposure can increase

00:54:12.420 | our baseline levels of dopamine robustly, 2.5X,

00:54:16.040 | and it's a long-lasting increase in dopamine,

00:54:18.080 | and it appears to be a healthy one,

00:54:19.300 | meaning it doesn't seem to be addictive.

00:54:20.940 | I'm sure there are some people out there addicted to ice baths

00:54:23.060 | but when you think about the range

00:54:24.940 | of dopamine-inducing behaviors that are addictive,

00:54:27.420 | it seems to be more on the health-promoting side.

00:54:29.860 | What's interesting is that

00:54:31.840 | because cold water exposure increases dopamine,

00:54:34.800 | it will also change your perception of time.

00:54:36.880 | And if you've ever done one of these cold water exposures,

00:54:38.960 | you've experienced this.

00:54:40.420 | You've experienced getting in and feeling like, wow,

00:54:43.360 | making it three minutes is a really, really long time.

00:54:45.920 | And you are fine slicing time.

00:54:47.580 | Your frame rate is going up.

00:54:49.020 | Part of that, just at a kind of a coarse level,

00:54:52.400 | as you're thinking, this is painful, I don't like this,

00:54:54.600 | I want to get out, right?

00:54:56.420 | But part of it is also that your dopamine levels

00:54:58.880 | are going up very quickly,

00:55:00.380 | and therefore your perception of that discomfort

00:55:03.300 | is also being fine sliced.

00:55:05.180 | And so you could leverage a tool, for instance,

00:55:07.820 | where you try and entrain your thinking

00:55:10.020 | to something other than your immediate experience, right?

00:55:12.980 | This is a kind of a controversy, if you will,

00:55:15.760 | in the cold exposure world.

00:55:18.420 | The question is, do you try and lean into the experience

00:55:21.360 | and really feel it, or do you try and distract yourself?

00:55:24.880 | Sing a song or count off from one to 100.

00:55:29.140 | Just know that whatever tactic you use

00:55:32.640 | to get through the cold exposure,

00:55:34.920 | that the dopamine level that's now increased in your system

00:55:38.680 | is going to cause you to fine slice

00:55:41.280 | or experience that at slow motion.

00:55:44.060 | So a minute is going to seem like a lot longer

00:55:46.300 | than a minute in reality.

00:55:48.980 | So you could, for instance,

00:55:51.380 | decide to pay attention to some external cue.

00:55:55.060 | Maybe it's a metronome that ticks once every 10 seconds.

00:55:59.540 | You could decide to think about something else.

00:56:02.320 | You could decide to sing a song in your head

00:56:04.300 | or sing a song out loud.

00:56:05.780 | All of that will divorce you from the sensation

00:56:08.340 | that you're experienced somewhat,

00:56:09.520 | but more so it will divorce you from the perception

00:56:13.380 | of your experience

00:56:14.740 | as governed by that dopamine increase in frame rate.

00:56:17.640 | If that isn't clear, just know this.

00:56:19.780 | When you're in the ice bath, your dopamine levels are high.

00:56:21.940 | When your dopamine levels are high,

00:56:23.700 | your experience of the discomfort of that ice bath

00:56:26.100 | is at higher resolution.

00:56:28.220 | Now, up until now, I've been talking about how dopamine

00:56:31.180 | and to some extent serotonin

00:56:33.740 | can differentially impact your perception of how fast

00:56:37.300 | or how slowly things are happening in the moment.

00:56:41.300 | But remember, we have prospective time,

00:56:43.820 | we have our experience of time in the moment,

00:56:46.100 | and we have retrospective time.

00:56:48.380 | And there are beautiful studies that have showed

00:56:51.180 | that the dopaminergic state changes the way,

00:56:56.040 | not just that we experience things now,

00:56:58.380 | but that it changes the way

00:57:00.740 | in which we remember things in the past

00:57:03.060 | and the rate at which those things occurred.

00:57:05.560 | And those are in opposite direction.

00:57:08.100 | So to make this very simple,

00:57:10.700 | if something that you experience is fun or varied,

00:57:15.520 | meaning it has a lot of different components in it,

00:57:18.620 | and is, in other words, is associated

00:57:20.660 | with an increase in dopamine in your brain,

00:57:23.060 | you will experience that as going by very fast.

00:57:29.200 | Now, this is different than the ice bath,

00:57:30.780 | which I just said you experience as going by very slowly,

00:57:32.980 | but here I'm talking about something that's fun

00:57:34.940 | and varied that you really like,

00:57:36.660 | and you'll feel like it goes by very, very fast.

00:57:38.780 | Imagine an amazing day for a kid in an amusement park.

00:57:42.280 | They can do a ton of things.

00:57:43.340 | It's all new.

00:57:44.280 | They're very excited,

00:57:45.760 | and they'll feel like it goes by very fast.

00:57:48.380 | But later, they will remember that experience

00:57:52.220 | as being very long,

00:57:54.580 | that it was a long day full of many, many events.

00:57:57.540 | And so there's this paradoxical relationship

00:58:00.340 | between how we perceive fun, exciting, varied events

00:58:03.440 | in the present and how we remember them in the past.

00:58:06.200 | For those of you who have gone on vacation,

00:58:08.340 | if you've had an amazing day on vacation,

00:58:10.040 | it'll seem like, or an amazing vacation overall,

00:58:12.280 | it will seem like it goes by very fast.

00:58:14.180 | The last day of vacation, you sort of go,

00:58:15.540 | whoa, it went by so fast 'cause there's so much happening.

00:58:18.680 | But in memory, six to eight months later, you remember,

00:58:21.700 | wow, that just went, you know, that was a long, long thing.

00:58:26.700 | We had this, then we had that, then we did this,

00:58:28.980 | then we had that.

00:58:29.820 | It tends to spool out in a longer memory

00:58:32.740 | than the actual experience.

00:58:34.740 | Conversely, if you are bored with something

00:58:38.460 | or it's something you really don't like,

00:58:40.280 | it's going to seem like it takes a long time

00:58:43.680 | to go through that experience in the moment.

00:58:46.180 | But retroactively, looking back,

00:58:48.060 | it will seem like that moment was very short.

00:58:50.260 | So if the other day I was waiting in the waiting room

00:58:52.940 | for the dentist, it was pretty boring.

00:58:54.800 | I was just kind of sitting there.

00:58:55.940 | There wasn't much going on.

00:58:57.740 | And it did seem like it was going on an awfully long time.

00:59:00.040 | But indeed, looking back, it just seems like,

00:59:01.820 | okay, I sat in that room, not much happened.

00:59:03.980 | And so it seems like a very short time been.

00:59:05.620 | This seems to be an efficiency

00:59:07.380 | of how the brain stores information.

00:59:09.240 | Dopamine being associated, of course,

00:59:12.320 | with fun and varied experiences

00:59:14.360 | and low dopamine being associated with kind of empty,

00:59:17.600 | boring, or what at the time seemed like long experiences.

00:59:22.000 | And this whole thing has been stamped down

00:59:24.420 | into the scientific literature by those earlier experiments

00:59:27.620 | where they take human beings

00:59:28.620 | and isolate them in certain environments.

00:59:30.620 | You know, take away all the clocks and watches and cues

00:59:33.380 | and about what time of day it is

00:59:35.420 | and what time of night it is

00:59:36.700 | and allow people to have a life

00:59:39.220 | where they can either read and work and do things

00:59:42.180 | or where they have very little to do.

00:59:44.140 | When people are isolated in very boring environments

00:59:47.540 | and they don't have access to time cues, time dilates.

00:59:51.420 | They tend to assume that time has gone on very, very long.

00:59:55.860 | And so the reason I bring this up is

00:59:58.100 | we aren't just driven by these circadian clocks

01:00:00.460 | and these circannual clocks and these ultradian clocks.

01:00:03.700 | We are driven by these timers

01:00:06.880 | that vary depending on our level of excitement.

01:00:10.660 | And they vary on depending on our level of excitement

01:00:13.480 | because of these neuromodulators, dopamine and serotonin.

01:00:16.100 | So the way I like to think about it

01:00:17.620 | is that you have two clocks, two stopwatches.

01:00:20.740 | One is a dopaminergic stopwatch

01:00:23.220 | that fine slices really closely.

01:00:25.200 | It's like counts off milliseconds

01:00:26.740 | and it's grabbing a movie of your experience

01:00:28.820 | at very high resolution.

01:00:30.180 | And then the other hand, you have a stopwatch

01:00:33.260 | that's gathering big time bins,

01:00:34.860 | big ticks along the hand is moving at bigger intervals,

01:00:39.860 | marking off time.

01:00:41.440 | And depending on whether or not you're excited

01:00:44.540 | or whether or not you're bored,

01:00:45.700 | you're using different stopwatches on time

01:00:48.740 | and therefore you're perceiving your experience differently.

01:00:51.980 | One very interesting aspect to the way that neuromodulators

01:00:55.420 | like dopamine and novelty interact with time perception

01:00:59.740 | and memory is how we perceive our relationship

01:01:03.820 | to places and people.

01:01:05.640 | So really interesting literature showing

01:01:08.720 | that the more novel experiences we have in a place,

01:01:11.560 | the more we feel we know that place obviously,

01:01:16.580 | but the longer we feel we've been there.

01:01:19.420 | So here's the kind of gedanken or thought experiment

01:01:21.780 | that illustrates what's in the literature.

01:01:24.280 | Let's say I were to move to New York City.

01:01:25.900 | I happen to really like New York City.

01:01:27.200 | I've never lived there,

01:01:28.040 | but let's say I lived there.

01:01:29.840 | I lived in a given apartment for a year

01:01:32.320 | and I would have a number of different experiences.

01:01:34.380 | In this mental experiment,

01:01:35.680 | let's say I had 100 different exciting and new experiences.

01:01:40.680 | I would, at the end of that year,

01:01:44.120 | feel as if I lived there a certain period of time, one year.

01:01:46.900 | I would actually know I lived there one year.

01:01:48.560 | If, however, I lived in three different places

01:01:50.540 | in New York City and I met three times as many people

01:01:53.260 | and I had three times as many novel experiences,

01:01:56.240 | I would actually feel as if I had been there much longer

01:01:59.800 | than had I only lived in one location.

01:02:01.980 | This is also true for social interactions.

01:02:04.580 | When we move to multiple or several novel environments

01:02:09.580 | with somebody else,

01:02:11.160 | we tend to feel as if we know that person much better

01:02:13.480 | and that they know us much better.

01:02:14.880 | Now, of course, we get the opportunity

01:02:16.140 | to interact with those people in different contexts

01:02:18.180 | and so indeed we do get the opportunity to see them,

01:02:21.140 | for instance, at the coffee shop, how they order coffee,

01:02:24.100 | you may be at the go to a sports event,

01:02:26.140 | how they act there, maybe how they interact with your family.

01:02:29.100 | You're getting a sense of them in different contexts.

01:02:32.040 | That's certainly playing a role,

01:02:34.680 | but it seems as if the more novelty you experience

01:02:37.760 | with somebody, not only the more familiar they are to you,

01:02:41.040 | but the more time you feel you've spent with them,

01:02:43.420 | even though the total amount of time

01:02:45.020 | can be exactly the same.

01:02:46.500 | And so that's a very interesting aspect

01:02:48.620 | of how our perception of time and these neuromodulators

01:02:51.180 | and novelty can shape the way,

01:02:53.000 | not just that we perceive a given event in our world,

01:02:56.900 | but how we relate to a place or relate to a person.

01:02:59.940 | So we've talked a lot about the different neurochemicals

01:03:02.840 | and how those neurochemicals

01:03:04.000 | can influence our perception of time.

01:03:06.020 | We haven't talked a lot about the neural circuits

01:03:08.120 | and the various areas of the brain that underlie this.

01:03:11.220 | I do want to touch on that

01:03:12.320 | by highlighting a really wonderful study.

01:03:15.300 | This was a study published in Neuron,

01:03:16.940 | also a cell press journal, excellent journal.

01:03:19.420 | The title of the paper is Behavioral, Physiological,

01:03:22.400 | and Neural Signatures of Surprise

01:03:24.780 | During Naturalistic Sports Viewing.

01:03:28.020 | This experiment is really cool.

01:03:29.100 | They did brain imaging on individuals

01:03:31.300 | who are watching basketball games.

01:03:33.820 | These were basketball games that actually took place,

01:03:36.460 | that were recorded.

01:03:37.800 | And the subjects watching these basketball games,

01:03:41.440 | in some cases, not all,

01:03:43.060 | had some interest in who would win or lose.

01:03:45.100 | And in some cases, not all,

01:03:46.780 | the subjects in these studies had some prior knowledge

01:03:49.760 | of which team they thought was better,

01:03:51.780 | which team was likely to win or not likely to win.

01:03:54.280 | The basic findings of the study

01:03:56.980 | were that they could measure surprise

01:04:00.120 | by the release of dopamine in two areas of the brain,

01:04:05.400 | part of what is called, excuse me,

01:04:07.440 | the mesolimbic reward pathway.

01:04:09.300 | So the two areas of the brain that are important here

01:04:10.860 | are the nucleus accumbens and the VTA,

01:04:13.340 | the ventral tegmental area.

01:04:14.580 | These are areas that release dopamine

01:04:17.500 | as kind of a token of reward

01:04:19.320 | any time something is surprising

01:04:21.620 | or a positive expectation is met, okay?

01:04:25.220 | So if I predict that my team dribbling down court

01:04:28.600 | is going to score on this drive

01:04:30.380 | and they get the ball in the basket,

01:04:31.940 | a little bit of dopamine is released.

01:04:33.260 | These two brain areas light up in the functional imaging,

01:04:37.080 | so-called fMRI, functional magnetic resonance imaging

01:04:40.260 | that they used in the study.

01:04:41.660 | What's really interesting about this study

01:04:44.860 | is not just that dopamine was released

01:04:47.820 | anytime that something the subject wanted to see happened,

01:04:52.060 | anytime they wanted to see their team score, they scored,

01:04:54.740 | but also during surprise.

01:04:56.620 | So if they thought, for instance,

01:04:58.740 | and they would hit a button to predict

01:05:01.060 | that their team was going to score on this particular drive

01:05:03.380 | and they didn't,

01:05:04.660 | well, then dopamine could also be released

01:05:07.120 | in response to that surprise.

01:05:09.020 | So this speaks again to dopamine

01:05:10.740 | being something that's important,

01:05:12.180 | not just for positive events, but for unexpected events.

01:05:16.060 | Now, that's all very interesting

01:05:18.100 | and speaks to the fact that dopamine

01:05:19.740 | is a kind of flexible currency in the brain.

01:05:22.420 | It's doled out, if you will, or released

01:05:25.540 | when something that one hopes will happen happens,

01:05:29.060 | and it's released when there's a surprise,

01:05:31.860 | even if it's kind of a negative surprise,

01:05:33.980 | it's not something that the subject wanted to happen.

01:05:37.220 | But the more interesting thing

01:05:39.060 | is how that relates to time perception.

01:05:42.200 | What they found was,

01:05:43.740 | regardless of what caused the dopamine release,

01:05:46.500 | the frequency of dopamine release

01:05:49.340 | predicted how the subjects parsed the time bins

01:05:53.460 | of the game they were watching.

01:05:55.700 | What do I mean by that?

01:05:56.660 | Well, when you watch a basketball game

01:05:58.340 | or you watch anything, children playing

01:06:00.420 | or talking to your spouse or whatever,

01:06:02.780 | you're batching time.

01:06:04.740 | How are you batching time?

01:06:06.500 | Well, you could batch a meal by the, I don't know,

01:06:09.580 | the appetizer, the main course, and the dessert,

01:06:12.200 | but it turns out that's not what you're doing.

01:06:14.640 | You're batching time according to the frequency

01:06:17.860 | of dopamine pulses, the frequency of dopamine release.

01:06:21.220 | And that's what they saw in this study.

01:06:23.000 | If they evaluated people's perceptions

01:06:25.220 | of the passage of time,

01:06:26.520 | what they found is that that matched,

01:06:28.260 | not whether or not it was a particular time point

01:06:31.920 | in the game, not whether or not their team

01:06:33.880 | was going down court or running back up court

01:06:36.140 | to play defense,

01:06:37.680 | but the dopamine release served as markers

01:06:42.340 | which would predict the frame rate

01:06:44.220 | of their perception of the experience.

01:06:45.960 | And if that sounds complicated,

01:06:47.400 | what I mean is how often and when you release dopamine

01:06:50.860 | is actually setting the frame rate

01:06:53.100 | on the entire perception of everything,

01:06:55.780 | not just for positive events or negative events.

01:06:58.740 | So what this means is as you were going through life,

01:07:01.380 | dopamine and the release of dopamine is saying,

01:07:07.140 | that's over and now you're in a new phase of your life,

01:07:10.120 | even if it's very short, right?

01:07:11.580 | So if I get up in the morning and I really need

01:07:13.900 | a cup of coffee, as you probably all know,

01:07:15.980 | I wait 90 minutes to 120 minutes before I drink my coffee,

01:07:19.980 | but then I get my coffee

01:07:20.940 | and surely there's a dopamine hit there, I promise you.

01:07:23.940 | I actually am starting to carve up my day

01:07:27.900 | according to dopamine hits.

01:07:29.520 | I am with consciously or subconsciously,

01:07:34.460 | I'm actually carving up my experience according

01:07:37.380 | to when I'm getting dopamine throughout my day.

01:07:39.820 | This governance over our perception of time

01:07:43.420 | that dopamine has points to a very clear,

01:07:47.040 | very actionable and very powerful tool.

01:07:50.500 | And that is a tool that many people have talked

01:07:52.540 | about before, which are habits.

01:07:54.660 | People have discussed habits in a variety of contexts,

01:07:58.700 | but in the context of dopamine reward

01:08:03.620 | and time perception, what this means is that placing

01:08:07.600 | specific habitual routines at particular intervals

01:08:12.600 | throughout your day is a very, not just convenient,

01:08:16.900 | but a very good way to incorporate the dopamine system

01:08:20.940 | so that you divide your day into a series

01:08:23.300 | of what I would call functional units.

01:08:25.100 | What would this look like?

01:08:26.180 | It would mean waking up and having one specific habit

01:08:28.520 | that you always engage in that causes a release of dopamine.

01:08:34.120 | You could say, well, great, that'll make me feel good.

01:08:36.920 | And I would agree, dopamine release generally makes us

01:08:40.080 | feel motivated, but it would have an additional effect

01:08:42.960 | of marking that time of day as the beginning

01:08:46.380 | of a particular time bin.

01:08:47.940 | Then inserting another habit, perhaps the beginning of,

01:08:50.960 | I don't know, your breakfast or something,

01:08:53.020 | but recognizing that that's a habit

01:08:54.760 | and being fairly habitual.

01:08:56.000 | You don't have to be obsessively precise about the timing,

01:09:00.060 | but that regular sequencing of things

01:09:04.460 | is going to lead not just to dopamine release

01:09:07.060 | as it relates to reward and motivation and feeling good,

01:09:09.980 | but it actually becomes the way in which we carve up

01:09:12.880 | our entire experience of our day.

01:09:15.260 | And this is almost a circular argument.

01:09:17.820 | You could say, well, of course, I do one thing,

01:09:19.760 | then I do the next, then I do the next,

01:09:21.380 | and that's how I perceive my day.

01:09:23.660 | That's my day, it's my list, it's my to-do list, et cetera.

01:09:27.200 | But what I'm saying is that on the basis of this study,

01:09:30.020 | I should mention the first author,

01:09:31.180 | his last name is Antony, it was Antony et al.,

01:09:34.020 | it was published in 2020, the study on basketball viewing,

01:09:39.020 | what it points to is that by engaging in specific habits

01:09:42.780 | that we know we can perform well,

01:09:45.040 | we are actually setting the frame rate on our day.

01:09:48.300 | And so I think there will soon come a time

01:09:50.560 | where human beings are not just thinking of,

01:09:52.680 | okay, my morning routine and my afternoon routine,

01:09:55.620 | I think that can be useful.

01:09:57.180 | And in fact, I used or mentioned a structure

01:09:59.660 | of that sort earlier in their episode,

01:10:01.520 | but rather thinking about what's actually going on

01:10:04.900 | at the level of our biology,

01:10:07.220 | which is that dopamine is marking time.

01:10:09.860 | Habits are a very clear way

01:10:11.740 | in which we can invoke dopamine release

01:10:14.180 | and therefore provide time markers.

01:10:16.420 | And what this means is that, for instance,

01:10:18.780 | during your morning, you might insert habit one

01:10:21.100 | and habit two at say, I don't know, 8 a.m. and 10 a.m.,

01:10:25.140 | and in doing that, that marks an epoch,

01:10:27.780 | a little batch of time in your morning routine

01:10:31.620 | that's distinct from the second half of your morning.

01:10:34.500 | In other words, habits serve as flankers or markers

01:10:38.620 | for the passage of your day.

01:10:40.860 | Now, if that seems kind of hyper neurotic

01:10:42.720 | or why would I want to structure my life like that,

01:10:44.980 | I would say that many people would do well

01:10:47.540 | to structure their life like that and to utilize habits,

01:10:50.380 | not just for sake of what you do during the habit,

01:10:52.800 | but because of the fact that the habits serve as a marker

01:10:56.100 | because of the way they can evoke dopamine release.

01:10:58.940 | And in doing that, you're able to segment your day

01:11:02.500 | into a bunch of smaller, if you want them to be smaller,

01:11:05.300 | or larger functional units.

01:11:07.380 | If anyone wants to experiment with this,

01:11:10.860 | the Huberman Lab podcast puts out a newsletter.

01:11:12.840 | It's called the Neural Network Newsletter.

01:11:14.380 | You can sign up for it at hubermanlab.com.

01:11:17.460 | We put it out each month.

01:11:18.460 | You can see the previous newsletters.

01:11:20.020 | They're zero cost.

01:11:20.960 | We have our privacy statement there.

01:11:22.360 | We don't share your email or anything.

01:11:24.080 | And there you'll find the 12 Steps to Improving Sleep

01:11:29.080 | was the first one.

01:11:30.040 | There's another, the second newsletter

01:11:31.680 | was all about neuroplasticity

01:11:33.080 | and using scientific literature

01:11:34.840 | to improve learning and teaching.

01:11:37.320 | And in the next newsletter,

01:11:39.000 | I intend to include a example protocol

01:11:41.760 | of how one could use habits

01:11:43.280 | and the relationship between habits and dopamine,

01:11:45.960 | dopamine and time perception to structure your day

01:11:48.640 | according to performance of particular types of tasks.

01:11:52.060 | Today, we covered a lot about time perception.

01:11:54.200 | We certainly didn't cover everything about time perception,

01:11:56.340 | but we covered things like entrainment,

01:11:57.920 | the role of dopamine, habits, and various routines

01:12:01.160 | that can adjust your sense of time

01:12:03.400 | for sake of particular goals.

01:12:05.400 | If you're interested in learning more about time perception,

01:12:08.440 | I'd like to point you to a really excellent book

01:12:10.880 | called "Your Brain is a Time Machine,

01:12:12.760 | "the Neuroscience and Physics of Time."

01:12:15.280 | The book was written by Professor Dr. Dean Buonamono,

01:12:18.080 | who's a professor at UCLA

01:12:19.480 | and a world expert in the neuroscience and physics of time.

01:12:23.440 | I do hope to get Dean on the podcast

01:12:25.580 | in the not too distant future.

01:12:27.400 | If you're learning from and/or enjoying this podcast,

01:12:29.940 | please subscribe to our podcast channel on YouTube.

01:12:32.560 | It's simply Huberman Lab on YouTube.

01:12:34.660 | And there, you can also leave us suggestions

01:12:37.520 | for future guests and topics

01:12:38.940 | and questions about the podcast episodes

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01:12:43.780 | In addition, please subscribe to our podcast

01:12:46.020 | on Apple and/or Spotify.

01:12:47.700 | And on Apple, you have the opportunity

01:12:49.320 | to leave us up to a five-star review.

01:12:52.040 | You can also follow us on Instagram.

01:12:53.960 | On Instagram, I do short neuroscience tutorials

01:12:56.640 | and tools and protocols.

01:12:57.880 | I cover recent papers,

01:12:59.400 | many of which are not included on the podcast.

01:13:02.220 | We also have a Patreon.

01:13:03.500 | It's patreon.com/andrewhuberman.

01:13:06.680 | And there, you can support the podcast

01:13:08.320 | at any level that you like.

01:13:10.080 | Not so much today, but on many previous episodes

01:13:12.320 | of the Huberman Lab Podcast, we discuss supplements.

01:13:15.020 | And while supplements aren't necessary for everybody,

01:13:17.920 | many people derive great benefit from supplements

01:13:20.200 | for sleep, for focus, and so forth.

01:13:22.840 | One issue with supplements, however,

01:13:24.240 | is that what's listed on the bottle of various supplements

01:13:27.120 | isn't always what's included in the bottle.

01:13:29.120 | And the quality of ingredients varies tremendously

01:13:31.720 | across different supplement manufacturers.

01:13:34.000 | For that reason, we've partnered with Thorne,

01:13:36.240 | that's T-H-O-R-N-E,

01:13:37.880 | because Thorne supplements have the highest levels

01:13:40.060 | of stringency of any supplement company out there

01:13:42.240 | that we are aware of.

01:13:43.360 | They work with all the major sports teams,

01:13:45.500 | they work with the Mayo Clinic,

01:13:46.620 | and so we're delighted that we partnered with them.

01:13:48.360 | If you'd like to see the supplements that I take,

01:13:50.260 | you can go to Thorne, that's T-H-O-R-N-E.com/u/huberman

01:13:55.260 | to see the supplements that I take,

01:13:57.140 | and you can get 20% off any of those supplements.

01:13:59.880 | If you enter the Thorne site through that portal,

01:14:02.220 | you can also get 20% off any of the supplements

01:14:04.920 | that Thorne makes.

01:14:06.160 | Thank you for your time and attention today.

01:14:08.160 | And last, but certainly not least,

01:14:10.340 | thank you for your interest in science.

01:14:12.300 | (upbeat music)

01:14:14.880 | (upbeat music)

Time Perception & Entrainment by Dopamine, Serotonin & Hormones | Huberman Lab Podcast #46

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