Essentials: Master Your Sleep & Be More Alert When Awake

00:00:00.000 | - Welcome to Huberman Lab Essentials,

00:00:02.320 | where we revisit past episodes

00:00:04.380 | for the most potent and actionable science-based tools

00:00:07.560 | for mental health, physical health, and performance.

00:00:10.320 | I'm Andrew Huberman,

00:00:12.880 | and I'm a professor of neurobiology and ophthalmology

00:00:15.840 | at Stanford School of Medicine.

00:00:18.080 | Today's podcast episode is all about sleep.

00:00:21.440 | We're also going to talk about the mirror image of sleep,

00:00:24.420 | which is wakefulness.

00:00:26.200 | Now, these two phases of our life, sleep and wakefulness,

00:00:29.560 | govern everything about our mental and physical health.

00:00:33.960 | And we're not just gonna talk about

00:00:35.540 | what's useful about sleep.

00:00:37.540 | We're also gonna talk about how to get better at sleeping,

00:00:40.520 | and that will include how to get better at falling asleep,

00:00:43.240 | timing your sleep, and accessing better sleep quality.

00:00:47.320 | In doing so, we're also gonna discuss

00:00:49.000 | how to get more focused and alert in wakefulness.

00:00:53.000 | So if you're like most people, which includes me,

00:00:56.320 | you have some challenges with sleep,

00:00:58.160 | at least every third or fifth night or so,

00:01:00.520 | and maybe even more often.

00:01:02.120 | So we're really gonna go tool heavy today

00:01:04.000 | and talk about tools that can help you fall asleep,

00:01:07.440 | sleep better, and emerge from sleep feeling more rested.

00:01:11.020 | So what determines how well we sleep

00:01:13.560 | and the quality of our wakeful state?

00:01:16.700 | Turns out that's governed by two forces.

00:01:19.200 | The first force is a chemical force.

00:01:21.840 | It's called adenosine.

00:01:24.120 | Adenosine is a molecule in our nervous system and body

00:01:27.380 | that builds up the longer we are awake.

00:01:30.260 | So if you've just slept for eight or nine

00:01:33.120 | or 10 really deep restful hours,

00:01:35.920 | adenosine is gonna be very low in your brain and body.

00:01:39.380 | If however, you've been awake for 10, 15 or more hours,

00:01:43.440 | adenosine levels are going to be much higher.

00:01:46.200 | Adenosine creates a sort of sleep drive or a sleep hunger.

00:01:50.840 | And a good way to remember this and think about adenosine

00:01:54.080 | is to think about caffeine.

00:01:56.540 | Caffeine for most people wakes them up.

00:01:59.440 | It makes them feel more alert.

00:02:01.640 | Caffeine acts as an adenosine antagonist.

00:02:06.240 | What that means is that when you ingest caffeine,

00:02:09.200 | whether or not it's coffee or soda or tea

00:02:11.380 | or in any other form, it binds to the adenosine receptor.

00:02:15.720 | It sort of parks there just like a car would park

00:02:18.140 | in a given parking slot.

00:02:19.440 | And therefore adenosine can't park in that slot.

00:02:22.900 | Now, when caffeine parks in the adenosine receptor slot,

00:02:26.180 | nothing really happens downstream of that receptor.

00:02:30.080 | The receptor can't engage the normal cellular functions

00:02:32.920 | of making that cell and you feel sleepy.

00:02:36.520 | So the reason caffeine wakes you up

00:02:39.320 | is because it blocks the sleepiness receptor.

00:02:43.080 | It blocks the sleepy signal.

00:02:44.800 | And this is why when that caffeine wears off,

00:02:47.480 | adenosine will bind to that receptor

00:02:49.560 | sometimes with even greater what we call affinity.

00:02:52.560 | And you feel the crash.

00:02:53.840 | You feel especially tired.

00:02:55.840 | Caffeine has a lot of health benefits.

00:02:58.700 | It also, for some people, can be problematic for health.

00:03:01.820 | It can raise blood pressure, et cetera.

00:03:03.920 | Caffeine increases this molecule

00:03:06.200 | that's a neuromodulator that we call dopamine.

00:03:08.760 | We discussed this in episode one,

00:03:10.680 | which tends to make us feel good, motivated,

00:03:13.120 | and give us energy.

00:03:14.720 | Because as you may have learned in episode one,

00:03:17.880 | dopamine is related to another neuromodulator

00:03:20.800 | called epinephrine, which gives us energy.

00:03:22.920 | In fact, epinephrine is made from dopamine.

00:03:25.360 | So let's just take a step back

00:03:26.640 | and think about what we're talking about

00:03:28.400 | when we're talking about sleepiness.

00:03:30.160 | If you've ever pulled an all-nighter,

00:03:31.920 | you'll notice something interesting.

00:03:33.800 | As morning rolls around,

00:03:35.480 | you'll suddenly feel an increase

00:03:37.160 | in your energy and alertness again,

00:03:39.080 | even though adenosine has been building up

00:03:41.880 | for the entire night.

00:03:44.200 | Why is that?

00:03:45.740 | The reason that is is because there's a second force,

00:03:48.280 | which is governing when you sleep and when you're awake.

00:03:51.380 | And that force is a so-called circadian force.

00:03:55.320 | Circadian means about a day or about 24 hours.

00:04:00.040 | And inside all of us is a clock

00:04:02.760 | that exists in your brain and my brain

00:04:05.080 | and the brain of every animal that we're aware of

00:04:08.480 | that determines when we want to be sleepy

00:04:11.560 | and when we want to be awake.

00:04:13.380 | That block of sleep and when it falls

00:04:16.240 | within each 24-hour cycle

00:04:18.400 | is governed by a number of different things.

00:04:21.680 | But the most powerful thing that's governing

00:04:23.400 | when you want to be asleep

00:04:24.800 | and when you want to be awake is light.

00:04:28.520 | And in particular, it's governed by sunlight.

00:04:31.140 | Now, I can't emphasize enough how important

00:04:33.560 | and how actionable this relationship is

00:04:36.460 | between light and when you want to sleep.

00:04:39.280 | It's quite simple on the face of it,

00:04:43.160 | and it's quite simple to resolve,

00:04:44.800 | but people tend to make a big mess

00:04:46.640 | of this whole circadian literature, frankly.

00:04:49.200 | So let's just break it down from the standpoint

00:04:52.000 | of what's going on in your brain and body

00:04:54.920 | as you go through one 24-hour day.

00:04:58.120 | Let's start with waking.

00:04:59.560 | So regardless of how well you slept at night

00:05:01.680 | or whether or not you were up all night,

00:05:03.080 | most people tend to wake up sometime

00:05:05.920 | around when the sun rises.

00:05:08.280 | When you wake up in the morning,

00:05:10.020 | you wake up because a particular hormone called cortisol

00:05:13.680 | is released from your adrenal glands.

00:05:15.960 | Your adrenal glands sit right above your kidneys,

00:05:18.120 | and there's a little pulse of cortisol.

00:05:20.080 | There's also a pulse of epinephrine,

00:05:23.040 | which is adrenaline, from your adrenals

00:05:25.960 | and also in your brain, and you feel awake.

00:05:29.280 | Now, that pulse of cortisol and adrenaline

00:05:32.000 | and epinephrine might come from your alarm clock.

00:05:34.200 | It might come from you naturally waking up.

00:05:36.840 | But it tends to alert your whole system in your body

00:05:40.120 | that it's time to increase your heart rate,

00:05:41.720 | it's time to start tensing your muscles,

00:05:43.240 | it's time to start moving about.

00:05:45.640 | It's very important that that cortisol pulse

00:05:48.720 | come early in the day,

00:05:50.800 | or at least early in your period of wakefulness.

00:05:53.560 | When you wake up in the morning

00:05:54.680 | and you experience that rise in cortisol,

00:05:57.880 | there's a timer that starts going,

00:06:00.440 | and these are cellular timers,

00:06:01.920 | and they're dictated by the relation

00:06:03.640 | between different organs in your body,

00:06:05.520 | that says to your brain and body

00:06:08.080 | that in about 12 to 14 hours, a different hormone,

00:06:12.280 | this hormone we're calling melatonin,

00:06:14.200 | will be released from your pineal gland.

00:06:17.160 | So there's two mechanisms here,

00:06:18.560 | a wakefulness signal and a sleepiness signal.

00:06:21.280 | And the wakefulness signal triggers the onset of the timer

00:06:25.080 | for the sleepiness signal.

00:06:26.800 | Okay, so the rhythm of cortisol and melatonin

00:06:31.120 | is what we call endogenous.

00:06:32.760 | It's happening in us all the time

00:06:34.800 | without any external input.

00:06:36.720 | In fact, if we were in complete darkness,

00:06:39.080 | living in a cave with no artificial lights whatsoever,

00:06:42.240 | these rhythms of cortisol and melatonin would continue.

00:06:46.080 | So if you were in complete darkness,

00:06:48.240 | it would happen once per 24-hour cycle,

00:06:51.360 | but it would be somewhat later and later each day.

00:06:56.040 | Whereas under normal circumstances,

00:06:59.280 | what happens is you wake up,

00:07:01.600 | and what happens when you wake up?

00:07:03.400 | You open your eyes.

00:07:04.720 | When you open your eyes, light comes into your eyes.

00:07:08.160 | Now, the way this system works

00:07:09.880 | is that you have a particular set of neurons

00:07:12.120 | in your eye, they're called retinal ganglion cells.

00:07:14.240 | When light comes into the eye,

00:07:15.880 | there's a particular group of retinal ganglion cells

00:07:18.880 | or type of retinal ganglion cells

00:07:21.200 | that perceives a particular type of light

00:07:24.400 | and communicates that to this clock

00:07:26.480 | that resides right above the roof of your mouth

00:07:28.320 | called the suprachiasmatic nucleus.

00:07:30.800 | And the suprachiasmatic nucleus has connections

00:07:34.720 | with essentially every cell and organ of your body.

00:07:38.340 | Now, it's vitally important

00:07:40.080 | that we get light communicated to this central clock

00:07:43.400 | in order to time the cortisol and melatonin properly.

00:07:47.400 | When I say properly, I can say that with confidence

00:07:50.280 | because we know based on a lot of evidence

00:07:52.800 | that if you don't get your cortisol

00:07:55.200 | and melatonin rhythms right,

00:07:57.520 | there are tremendously broad and bad effects

00:08:02.520 | on cardiovascular health, metabolic effects,

00:08:05.760 | learning, depression, dementia.

00:08:08.280 | So let's think about what happens

00:08:10.360 | when we do this correctly and how to do it correctly.

00:08:12.940 | When we wake up, our eyes open.

00:08:15.220 | Now, if we're in a dark room,

00:08:17.600 | there isn't enough light to trigger the correct timing

00:08:21.680 | of this cortisol melatonin thing, these rhythms.

00:08:25.700 | You might say, well, why won't any light do it?

00:08:28.780 | Well, it turns out that these neurons in our eye

00:08:32.020 | that set the circadian clock

00:08:33.680 | and then allow our circadian clock

00:08:35.460 | to set all the clocks of all the cells and organs

00:08:37.740 | and tissues of our body,

00:08:39.340 | responds best to a particular quality of light

00:08:43.800 | and amount of light.

00:08:45.120 | And those are the qualities of light

00:08:48.680 | and amount of light that come from sunlight.

00:08:51.760 | So these neurons, what they're really looking for,

00:08:56.440 | although they don't have a mind of their own,

00:08:58.400 | is the sun at what we call low solar angle.

00:09:01.840 | The eye and the nervous system don't know anything

00:09:03.480 | about sunrises or sunsets.

00:09:05.260 | It only knows the quality of light that comes in

00:09:08.720 | when the sun is low in the sky.

00:09:10.320 | The system evolved so that when the sun is low in the sky,

00:09:14.240 | there's a particular contrast between yellows and blues

00:09:17.640 | that triggers the activation of these cells.

00:09:20.280 | However, if you wake up a few hours after the sunrise,

00:09:23.480 | which I tend to most days personally,

00:09:26.420 | you still want to get outside and view sunlight.

00:09:30.120 | You don't need the sunlight beaming you

00:09:31.960 | directly in the eyes.

00:09:33.080 | There's a lot of photons, light energy,

00:09:35.460 | that's scattered from sunlight at this time.

00:09:38.060 | But the key is to get that light energy from sunlight,

00:09:42.720 | ideally into your eyes.

00:09:44.300 | It's critically important that you get outside

00:09:46.420 | to get this light.

00:09:47.980 | I had a discussion with a colleague of mine,

00:09:49.840 | Dr. Jamie Zeitzer,

00:09:50.900 | who's in the Department of Psychiatry and Behavioral

00:09:53.580 | Sciences at Stanford, a world expert in this.

00:09:58.020 | And he tells me that it's 50 times less effective

00:10:03.480 | to view this sunlight through a window,

00:10:07.040 | through a car windshield, or through a side window of a car,

00:10:10.660 | than it is to just get outside with no sunglasses

00:10:13.660 | and view light early in the day.

00:10:16.060 | Once the sun is overhead, the quality of light shifts

00:10:19.500 | so that you miss this opportunity

00:10:21.580 | to time the cortisol pulse.

00:10:23.460 | And that turns out to be a bad thing to do.

00:10:26.920 | You really want to time that cortisol pulse properly

00:10:30.100 | because, we'll get into this a little bit more later,

00:10:33.260 | but a late shifted cortisol pulse,

00:10:36.420 | in particular a 9 p.m. or 8 p.m. increase in cortisol,

00:10:40.480 | is one of the consequences and maybe one of the causes

00:10:45.480 | of a lot of anxiety disorders and depression.

00:10:48.460 | So it's kind of a chicken egg thing.

00:10:49.580 | We don't know whether or not it's the correlated with,

00:10:51.560 | it's the cause or the effect,

00:10:53.540 | but it's a signature of depression and anxiety disorder.

00:10:56.800 | Bringing that cortisol pulse earlier in your wakeful period,

00:11:00.640 | earlier in your day, has positive benefits,

00:11:03.940 | ranging from blood pressure to mental health, et cetera.

00:11:07.440 | I'm not going to list them all off

00:11:08.480 | 'cause there's just so many of them,

00:11:10.160 | but many, many positive things happen

00:11:12.360 | when you are getting the cortisol early in the day,

00:11:15.560 | far away from your melatonin pulse.

00:11:18.320 | Okay, so how long should you be outside?

00:11:21.020 | Well, this is going to vary tremendously

00:11:23.220 | because some people live in environments

00:11:24.800 | where it's very bright.

00:11:25.640 | So let's say it's Colorado in the middle of winter,

00:11:29.480 | there's a snow field,

00:11:30.580 | there's no cloud cover and you walk outside,

00:11:32.960 | there's going to be so much photon light energy

00:11:36.140 | arriving on your retina

00:11:37.640 | that it probably only takes 30 to 60 seconds

00:11:39.800 | to trigger the central clock

00:11:41.400 | and set your cortisol and melatonin rhythms properly

00:11:44.040 | and get everything lined up nicely.

00:11:47.080 | Whereas if you're in Scandinavia in the depths of winter

00:11:50.920 | and you wake up at 5 a.m.

00:11:52.120 | and the sun is just barely creeping across the horizon

00:11:54.680 | then goes back down again a few hours later,

00:11:57.120 | you probably are not getting enough sunlight

00:12:00.860 | in order to set these rhythms.

00:12:03.180 | So many people find that they need to use

00:12:06.480 | sunlight simulators in the form of particular lights

00:12:10.000 | that were designed to simulate sunlight.

00:12:11.760 | You could say, well, the lights in my house or my phone

00:12:14.620 | are really, really bright, right?

00:12:16.120 | Everyone's telling us to stay off our phones at night

00:12:17.920 | because they're really bright, but guess what?

00:12:20.320 | It turns out that early in the day,

00:12:22.520 | your retina is not very sensitive,

00:12:25.440 | which means you need a lot of photons

00:12:28.320 | ideally coming from sunlight to set these clock mechanisms.

00:12:31.480 | So looking at your phone or artificial lights is fine

00:12:33.760 | if you wake up before sunrise,

00:12:36.040 | but it's not going to work to set these clock mechanisms.

00:12:40.600 | So you want to use sunlight.

00:12:42.160 | If you can't see sunlight because of your environment,

00:12:45.300 | then you are going to have to opt for artificial light.

00:12:48.600 | And in that case, you're going to want an artificial light

00:12:51.140 | that either simulate sunlight or has a lot of blue light.

00:12:55.000 | Now, without going off course here, you might be saying,

00:12:57.840 | wait, I've heard blue light is bad for me.

00:12:59.820 | Actually, blue light is great for this mechanism

00:13:02.740 | during the day.

00:13:04.120 | A lot of people will say,

00:13:04.960 | oh, I should be wearing blue blockers throughout the day.

00:13:07.040 | No, that's the exact wrong thing.

00:13:09.460 | That should be reserved for late in the evening

00:13:12.300 | because light suppresses melatonin.

00:13:15.680 | Sunlight inhibits the pineal.

00:13:18.460 | It prevents it from releasing melatonin.

00:13:21.560 | Darkness allows the pineal to release melatonin.

00:13:25.480 | So the pineal is not the gland or the organ of sunlight.

00:13:29.260 | It is the gland of darkness.

00:13:31.160 | In fact, melatonin can be thought of as a sleepiness signal

00:13:34.480 | that's correlated with darkness.

00:13:36.240 | So get up each morning, try and get outside.

00:13:39.340 | I know that can be challenging for people,

00:13:41.000 | but anywhere from two to 10 minutes of sunlight exposure

00:13:45.400 | is going to work well for most people.

00:13:47.160 | If you can't do it every day,

00:13:48.320 | or you sleep through this period of the early day,

00:13:50.720 | low solar angle, don't worry about it.

00:13:53.140 | The systems in the body,

00:13:54.520 | these hormone systems and neurotransmitter systems

00:13:57.060 | that make you awake at certain periods of the day

00:13:59.560 | and sleepy at other times are operating by averaging

00:14:04.520 | when you view the brightest light.

00:14:06.900 | Some of you, many of you might be asking,

00:14:10.860 | what else can help set this rhythm?

00:14:12.660 | Well, it turns out that light

00:14:14.220 | is what we call the primary zeitgeber,

00:14:16.580 | the time giver.

00:14:18.680 | But other things can help establish this rhythm of cortisol

00:14:23.640 | followed by melatonin 12 to 16 hours later as well.

00:14:27.220 | The other things besides light are timing of food intake,

00:14:31.740 | timing of exercise,

00:14:33.660 | as well as various drugs or chemicals that one might ingest.

00:14:38.100 | Not illegal drugs,

00:14:39.180 | although those will impact circadian mechanisms as well.

00:14:42.760 | The other thing is sunset.

00:14:44.700 | When the sun is also at low solar angle,

00:14:47.880 | low close to the horizon,

00:14:49.540 | by viewing sunlight at that time of day in the evening

00:14:53.740 | or afternoon, depending on what time of year it is

00:14:55.620 | and where you are in the world,

00:14:57.540 | these melanopsin cells, these neurons in your eyes

00:15:00.060 | signal the central circadian clock

00:15:02.180 | that it's the end of the day.

00:15:04.500 | There was a really nice study that showed

00:15:07.420 | that viewing sunlight around the time of sunset

00:15:11.540 | doesn't have to be just crossing the horizon,

00:15:13.940 | but circa sunset within an hour or so of sunset

00:15:17.820 | prevents some of the bad effects of light

00:15:22.560 | in preventing melatonin release later that same night.

00:15:26.500 | So let me repeat this.

00:15:27.420 | Viewing light early in the day is key.

00:15:28.960 | Viewing light later in the day when the sun is setting

00:15:32.140 | or around that time can help protect these mechanisms,

00:15:36.580 | your brain and body,

00:15:37.920 | against the negative effects of light later in the day.

00:15:41.460 | So let me talk about how you would do that.

00:15:43.940 | You'd go view the sunset

00:15:45.260 | or you would go outside in the late afternoon or evening.

00:15:48.460 | Again, if you want to do this through a window at work,

00:15:50.340 | that's fine, but it'll take 50 times longer.

00:15:52.740 | So the best thing to do is just to get outside

00:15:54.900 | for a few minutes,

00:15:55.740 | anywhere from two to 10 minutes also in the afternoon.

00:15:58.420 | Having those two signals arriving to your central clock

00:16:01.780 | that your body, your internal world

00:16:04.220 | knows when it's morning and knows when it's evening

00:16:06.420 | is tremendously powerful.

00:16:08.080 | There's always a lot of questions about how long,

00:16:11.180 | how much, how do I know if I've had enough?

00:16:12.780 | You'll know because your rhythm will start to fall

00:16:15.960 | into some degree of normalcy.

00:16:18.100 | You'll start to wake up at more or less the same time

00:16:20.100 | each day.

00:16:20.940 | You'll fall asleep more easily at night.

00:16:22.260 | Generally, it takes about two or three days

00:16:23.980 | for these systems to align.

00:16:25.660 | So if you've not been doing these behaviors,

00:16:27.900 | it's going to take a few days,

00:16:29.140 | but they can have tremendous benefits

00:16:31.260 | and sometimes rather quickly on a number of different

00:16:33.860 | mental and physical aspects of your health.

00:16:35.980 | Now let's talk about the bad effects of light

00:16:39.860 | because light is not supposed to arrive in our system

00:16:44.380 | at any time.

00:16:45.580 | And nowadays, because of screens and artificial light,

00:16:48.500 | we have access to light at times of day and night

00:16:52.600 | that normally we wouldn't.

00:16:54.620 | Now, earlier I said that you need a lot of light

00:16:57.320 | in particular sunlight to set these clock mechanisms.

00:17:00.340 | That's true, but there's a kind of diabolical feature

00:17:03.140 | to the way all this works,

00:17:04.260 | which is the longer you've been awake,

00:17:08.020 | the more sensitive your retina and the cells are to light.

00:17:12.100 | So that if you've been awake for 10, 12, 14 hours,

00:17:15.860 | it becomes very easy for even a small amount of light

00:17:18.780 | coming from a screen or from an overhead light

00:17:23.500 | to trigger the activation of the clock

00:17:25.820 | and make you feel like you want to stay up later,

00:17:27.700 | make it harder to fall asleep

00:17:28.940 | and disrupt your sleep pattern.

00:17:31.100 | Okay, so the simple way to think about this

00:17:33.500 | is you want as much light as is safely possible

00:17:36.300 | early in the day, morning and throughout the day,

00:17:38.660 | including blue light.

00:17:40.060 | And you want as little light coming into your eyes,

00:17:43.060 | artificial or sunlight after say 8 p.m.

00:17:46.780 | And certainly you do not want to get bright light exposure

00:17:49.740 | to your eyes between 11 p.m. and 4 a.m.

00:17:51.820 | And here's why.

00:17:53.020 | Light that arrives to the eyes

00:17:56.900 | between 11 p.m. and 4 a.m. approximately

00:18:00.720 | suppresses the release of dopamine,

00:18:04.180 | this neuromodulator that makes us feel good

00:18:06.100 | as sort of an endogenous antidepressant

00:18:09.660 | and can inhibit learning

00:18:10.880 | and create all sorts of other detrimental effects.

00:18:14.460 | It does this through a mechanism,

00:18:16.140 | for those of you who want to know the neural pathways,

00:18:18.320 | that involves light to the eyes

00:18:19.740 | that's then signaled to a structure called the habenula.

00:18:22.400 | When that habenula gets activated,

00:18:24.340 | it's actually called the disappointment nucleus

00:18:27.100 | because it actually makes us feel less happy

00:18:31.060 | and more disappointed

00:18:32.160 | and can lead to certain forms of depression

00:18:34.660 | in the wakeful state.

00:18:36.140 | Now, if you wake up in the middle of the night

00:18:37.460 | and you need to use the bathroom

00:18:38.420 | or you're on an all night flight

00:18:39.740 | and you need to read or whatever it is, fine.

00:18:44.300 | Every once in a while, it's not going to be a problem

00:18:47.300 | to get bright light exposure to your eyes

00:18:49.380 | in the middle of the night.

00:18:50.820 | But if you think about our lifestyle nowadays

00:18:53.500 | and being up late looking at phones,

00:18:55.100 | even if you dim that screen,

00:18:56.780 | you're triggering this activation

00:18:58.660 | because your retinal sensitivity

00:19:00.140 | and the sensitivity of these neurons

00:19:01.500 | has gone up late in the day.

00:19:03.000 | For those of you that are experiencing challenges with mood,

00:19:06.100 | those of you that have anxiety, learning problems,

00:19:08.200 | issues focusing, the questions I usually get

00:19:10.180 | are how can I focus better?

00:19:11.380 | One of the best ways you can support your mechanisms

00:19:13.980 | for good mood, mental health,

00:19:15.900 | learning, focus, metabolism, et cetera,

00:19:18.740 | is to take control of this light exposure behavior at night

00:19:23.100 | and not get much or any bright light exposure

00:19:26.220 | in the middle of the night.

00:19:27.140 | These cells in our eye, these neurons

00:19:29.740 | that signal the central clock reside mostly,

00:19:33.220 | not exclusively, but mostly in the bottom half

00:19:35.640 | of our retina.

00:19:36.880 | And because we have a lens in front of our retina

00:19:39.320 | and because of the optics of lenses,

00:19:41.420 | that means that these cells are actually viewing

00:19:43.960 | our upper visual field.

00:19:45.600 | This is probably not coincidental

00:19:48.200 | that these cells were essentially designed

00:19:51.620 | to detect sunlight, which is overhead, of course.

00:19:55.460 | So if you want to avoid improper activation of these neurons,

00:20:00.460 | it's better to place lights that you use in the evening

00:20:06.300 | low in your physical environment.

00:20:08.140 | So on desktops or even the floor,

00:20:10.300 | if you want to go that way, as opposed to overhead lights.

00:20:15.300 | So overhead fluorescent lights would be the worst.

00:20:18.260 | That would be the worst case scenario.

00:20:20.660 | Lights that are overhead that are a little bit softer

00:20:23.100 | of the sort of yellow or reddish tints

00:20:25.380 | would be slightly better.

00:20:26.420 | But dim lights that are set low in the room

00:20:29.020 | are going to be best

00:20:30.060 | because they aren't going to activate these neurons

00:20:33.540 | and therefore shift your circadian clock.

00:20:36.180 | But let's talk about what light can do

00:20:39.480 | in terms of shifting us in healthy ways.

00:20:42.700 | So the way to think about this whole system,

00:20:45.380 | again, is you've got adenosine building up

00:20:47.100 | depending on how long you've been awake

00:20:49.220 | and it's making you sleepy.

00:20:50.300 | And then you've got the circadian mechanisms

00:20:51.940 | that are timing your wakefulness

00:20:53.620 | and timing when you want to be asleep.

00:20:55.220 | Mainly through cortisol and melatonin.

00:20:57.540 | But there are a bunch of other things

00:20:58.620 | that are downstream of cortisol and melatonin.

00:21:00.700 | Like we tend to be hungrier during our wakeful period

00:21:05.220 | than late at night.

00:21:06.180 | Some people like to eat it late at night.

00:21:07.940 | But if you're finding that you can't become a day person

00:21:10.840 | or a morning person, shifting your light exposure,

00:21:14.060 | exercise and food intake to the daytime will help.

00:21:17.380 | Jamie Zeitzer and colleagues did a beautiful study

00:21:20.420 | showing that if you turn on the lights before waking up,

00:21:25.420 | so around 45 minutes to an hour before waking up,

00:21:28.840 | even if your eyelids are closed,

00:21:30.360 | provided you're not under the covers,

00:21:32.660 | after doing that for a few days,

00:21:35.740 | that increases your total sleep time

00:21:38.420 | and shifts forward the time at which you feel sleepy.

00:21:41.380 | It makes you want to go to bed earlier each night.

00:21:44.700 | Now, in a kind of a diabolical way,

00:21:47.180 | they did this with teenagers who are notorious

00:21:49.740 | for wanting to wake up late and stay up late.

00:21:51.500 | And what they found was bright light flashes,

00:21:53.940 | just turning on the lights in their environment,

00:21:55.420 | overhead lights, 'cause they're trying

00:21:56.820 | to activate the system.

00:21:58.060 | And that's why they're using overhead lights.

00:22:00.520 | Even through the eyelids, before these kids woke up,

00:22:04.120 | then made those kids naturally want to go to bed earlier

00:22:06.680 | and they ended up sleeping longer.

00:22:08.220 | So that's something you could try.

00:22:09.220 | You could put your lights on a timer to go on

00:22:12.300 | early in the day before you wake up.

00:22:15.000 | You could open your blinds so that sunlight

00:22:17.060 | is coming through.

00:22:18.260 | Now, again, if you curl up under the covers,

00:22:20.580 | then it's not going to reach these neurons,

00:22:23.300 | but it's remarkable the light can actually penetrate

00:22:25.420 | the eyelids, activate these neurons,

00:22:27.140 | and go to the central clock.

00:22:28.540 | That study illustrates a really important principle

00:22:31.940 | of how you're built, which is you have the capacity

00:22:35.080 | for what are called phase advances and phase delays.

00:22:39.040 | And I don't want to complicate this too much.

00:22:41.180 | So the simplest way to think about phase advances

00:22:44.540 | and phase delays is that if you see light late in the day,

00:22:49.540 | and in particular, in the middle of the night,

00:22:51.900 | your brain and body, for reasons that now you understand,

00:22:56.320 | will think that that's morning light,

00:22:58.420 | even though it's not sunlight,

00:22:59.560 | because you have this heightened sensitivity,

00:23:01.140 | and it will phase delay, it will delay your clock.

00:23:03.900 | It will essentially make you want to get up later

00:23:06.020 | and go to sleep later.

00:23:07.620 | So the simple way to think about this

00:23:09.940 | is if you're having trouble waking up early

00:23:12.100 | and feeling alert early in the day,

00:23:14.900 | you're going to want to try and get bright light exposure

00:23:17.500 | even before waking up, because it will advance your clock.

00:23:20.780 | It's sort of like turning the clock forward.

00:23:23.420 | Whereas if you are having trouble waking up early,

00:23:25.940 | you definitely don't want to get too much light exposure

00:23:29.140 | or any light exposure to your eyes late in the evening

00:23:32.620 | and in the middle of the night,

00:23:33.460 | because it's just going to delay your clock more and more.

00:23:36.180 | And what you're trying to do is provide them anchors.

00:23:38.940 | You're trying to provide them consistent, powerful anchors

00:23:42.380 | so that your cortisol, your melatonin,

00:23:45.740 | and then everything that cascades down from that,

00:23:48.920 | like your metabolism and your ability to learn

00:23:51.660 | and your sense of alertness, your dopamine, your serotonin,

00:23:54.740 | all that stuff is timed regularly.

00:23:58.100 | One of the reasons why there's so much challenge out there

00:24:03.100 | with focus and anxiety and depression,

00:24:06.460 | there are a lot of reasons for that,

00:24:07.780 | but one of the reasons is that people's internal mechanisms

00:24:11.900 | aren't anchored to anything regular.

00:24:13.740 | These systems, again, will average,

00:24:15.260 | but if you can provide them consistent light anchors

00:24:18.380 | early in the day and in the evening

00:24:20.260 | and avoiding light at night,

00:24:21.820 | you will be amazed at the tremendous number

00:24:24.180 | of positive effects that can come from that

00:24:26.500 | at the level of metabolic factors, hormones,

00:24:29.460 | and just general feelings of wellbeing.

00:24:31.560 | And this is why whenever people ask me, what should I take,

00:24:35.060 | which is one of the most common questions I get,

00:24:36.800 | what supplements should I take?

00:24:37.860 | What drugs should I be taking?

00:24:39.020 | What things should I be taking?

00:24:40.600 | The first question I always ask them is, how's your sleep?

00:24:45.600 | And 90% of the time, they tell me they either have trouble

00:24:48.800 | falling asleep or staying asleep,

00:24:50.100 | or they don't feel rested throughout the day.

00:24:52.700 | A brief note about naps.

00:24:54.920 | Naps, provided that they're less than one ultradian cycle,

00:24:57.900 | for either 20 minutes or 30 minutes, or even an hour,

00:25:00.860 | can be very beneficial for a lot of people.

00:25:02.940 | You don't have to take them,

00:25:04.580 | but many people naturally feel a dip in energy and focus

00:25:07.880 | late in the afternoon.

00:25:08.940 | In fact, if we were going to look at wakefulness,

00:25:11.080 | what we would find is that you get

00:25:12.320 | that morning light exposure, hopefully,

00:25:13.760 | your cortisol goes up, people start feeling awake,

00:25:15.840 | and then around two or three or four in the afternoon,

00:25:18.160 | there's a spike in everything from alertness

00:25:21.740 | to ability to learn, some metabolic factors drop,

00:25:24.760 | and then it just naturally comes back up,

00:25:26.880 | and then it tapers off as the night goes on.

00:25:29.520 | So for some of you, naps are great.

00:25:32.040 | I love taking naps.

00:25:33.640 | Some people, they wake up from naps feeling really groggy.

00:25:36.740 | That's probably because they're not sleeping as well

00:25:39.640 | as they should at night, or as long as they should at night,

00:25:42.020 | and so they're dropping into REM sleep

00:25:44.660 | or deeper forms of sleep in the daytime,

00:25:47.380 | and then they wake up and they feel kind of disoriented.

00:25:49.580 | Other people feel great after a nap.

00:25:51.180 | So that's another case where, just like with caffeine,

00:25:53.780 | you sort of have to evaluate for yourself.

00:25:55.900 | Okay, so naps are going to be good for some people,

00:25:57.820 | not for others.

00:25:58.660 | I personally like to take a nap around three or 4 p.m.,

00:26:01.820 | but there's a practice that I've adopted

00:26:03.920 | in the last five years

00:26:05.520 | that I've found to be immensely beneficial

00:26:08.080 | that is sort of like napping, but isn't napping.

00:26:11.040 | It's a thing that they call yoga nidra.

00:26:14.440 | Yoga nidra actually means yoga sleep,

00:26:16.720 | and it's a sort of meditation that you listen to.

00:26:19.320 | Meditation and yoga nidra scripts

00:26:21.660 | have been immensely helpful for me

00:26:23.680 | in terms of accelerating the transition to sleep.

00:26:27.000 | So they involve taking a few minutes,

00:26:29.840 | 10 to 30 minutes or so, just like you would for a nap,

00:26:32.540 | and just listening to a script, almost passively.

00:26:35.620 | And it has you do some particular patterns of breathing

00:26:38.800 | and some other kind of body scan-like things

00:26:41.700 | that can really help people learn to relax,

00:26:44.220 | not just in that moment,

00:26:45.740 | but get better at relaxing and turning off thinking

00:26:48.600 | in order to fall asleep when they want to do that at night.

00:26:51.260 | In other words, they're always good for you

00:26:53.220 | because it's a training mechanism

00:26:54.860 | by which you self-train your nervous system

00:26:57.100 | to go from a state of heightened alertness

00:26:59.640 | that you don't want to heightened relaxation

00:27:02.420 | that you do want.

00:27:03.780 | And so it's really teaching you to hit the brake.

00:27:06.660 | And that brings us to an even more important point perhaps,

00:27:09.340 | which is we've all experienced

00:27:11.900 | that we can stay up if we want to, right?

00:27:14.740 | If we want to stay up late on New Year's

00:27:17.260 | or we want to push an all-nighter,

00:27:18.660 | some people can do that more easily than others,

00:27:21.160 | but we're all capable of doing that.

00:27:23.720 | But it's very hard to make ourselves fall asleep.

00:27:26.260 | And so there's a sort of asymmetry

00:27:28.060 | to the way our autonomic nervous system,

00:27:30.000 | which governs this alertness calmness thing,

00:27:32.200 | the sympathetic and parasympathetic nervous system.

00:27:34.680 | There's an asymmetry there

00:27:35.940 | where we are more easily able to engage wakefulness

00:27:39.840 | and drive wakefulness.

00:27:40.880 | We can force ourselves to stay awake.

00:27:43.040 | Then we are able to force ourselves to fall asleep.

00:27:46.840 | And one of the things that I say over and over again,

00:27:49.720 | and I'm going to continue to say over and over again,

00:27:51.840 | is it's very hard to control the mind with the mind.

00:27:54.820 | When you have trouble falling asleep,

00:27:56.640 | you need to look to some mechanism that involves the body.

00:27:59.620 | And all the things I described,

00:28:01.020 | meditation, hypnosis, yoga nidra,

00:28:03.820 | all involve exhale-emphasized breathing,

00:28:07.100 | certain ways of lying down and controlling the body.

00:28:10.140 | We're going to get into breathing

00:28:11.460 | in real depth at another time.

00:28:13.460 | But all of those involve using the body to control the mind

00:28:16.980 | rather than trying to, you know,

00:28:19.300 | wrestle your mind into a certain pattern of relaxation.

00:28:22.940 | And when we're having trouble controlling the mind,

00:28:25.060 | I encourage people to look towards the body,

00:28:27.540 | look toward sunlight, avoid sunlight and bright light

00:28:30.660 | if that happens to be late at night.

00:28:32.520 | So there's a theme that's starting to emerge,

00:28:34.700 | which is in order to control this thing

00:28:36.040 | that we call the nervous system,

00:28:37.440 | we have to look back to some of the things

00:28:39.660 | we discussed earlier, like sensation, perception, et cetera.

00:28:42.880 | But we have to ask, what can we control?

00:28:45.080 | Well, I'm talking about controlling light exposure,

00:28:47.120 | controlling your breathing and body,

00:28:49.360 | non-sleep deep rest,

00:28:51.120 | or what hereafter we will refer to as NSDR,

00:28:55.720 | non-sleep deep rest,

00:28:57.400 | as a way to reset one's ability to be awake

00:29:01.640 | after you emerge from NSDR.

00:29:03.440 | So to get some more wakefulness and ability to attend,

00:29:05.920 | some emotional stability reset,

00:29:08.880 | as well as make it better and easier to fall asleep

00:29:13.000 | when you want to go to sleep at night.

00:29:14.800 | Now, non-sleep deep rest

00:29:16.360 | does have some research to support it.

00:29:18.500 | There's a beautiful study done out of a university

00:29:21.520 | in Denmark, I will later provide a link to that study,

00:29:25.000 | that showed that this meditation

00:29:27.720 | and yoga nidra type meditation

00:29:30.560 | allows dopamine and other neuromodulators

00:29:33.440 | in an area of the brain called the striatum,

00:29:35.100 | that's involved in motor planning and motor execution,

00:29:38.360 | to reset itself.

00:29:39.720 | In other words, this NSDR can reset our ability

00:29:43.200 | to engage in the world in a way that's very deliberate.

00:29:46.680 | Okay, so what about things that we can

00:29:49.100 | and maybe should or should not take

00:29:51.060 | in order to control and access better sleep

00:29:54.340 | and better wakefulness?

00:29:55.420 | There are a couple of things that are directly in line

00:29:57.940 | with the biology related to falling and staying asleep

00:30:00.400 | and directly in line with the biology of wakefulness.

00:30:03.420 | There's a whole category of things like stimulants,

00:30:06.940 | cocaine, amphetamine, and prescription stimulants

00:30:10.420 | that are the prescription ones

00:30:12.020 | were designed for the treatment of narcolepsy.

00:30:13.940 | So things like modafinil or armadafinil

00:30:17.260 | that are designed to create wakefulness.

00:30:18.660 | They are all essentially chemical variants

00:30:23.180 | of things that increase epinephrine and dopamine.

00:30:26.100 | Now, of course, I'm of the standpoint

00:30:28.620 | that things like cocaine and amphetamine

00:30:30.140 | are just across the board bad.

00:30:31.660 | They have so many addictive and terrible effects.

00:30:34.560 | In the proper setting prescribed by the proper professional,

00:30:38.580 | things like modafinil for narcolepsy might be appropriate.

00:30:42.800 | I know that a lot of people out there take Adderall,

00:30:46.080 | even though they haven't been prescribed Adderall

00:30:48.580 | in order to increase wakefulness.

00:30:50.880 | That is essentially, well, it's illegal for one,

00:30:54.540 | but it's also, it's abusing the system in the sense

00:30:57.060 | that you're pushing back on the adenosine system

00:30:59.240 | slightly differently than you do caffeine.

00:31:01.620 | It will make you feel more alert.

00:31:02.860 | There tends to be a heavy rebound

00:31:04.060 | and they do have an addictive potential.

00:31:05.860 | There are also some other effects of those

00:31:07.420 | that can be quite bad,

00:31:08.260 | but there are some supplements and some things

00:31:10.280 | that are safer, certainly safer.

00:31:13.660 | And that in cases where you're doing

00:31:16.520 | all the right behaviors,

00:31:17.580 | you're exercising and eating correctly,

00:31:20.100 | and you're still having trouble with sleep,

00:31:21.800 | that can be beneficial for falling and staying asleep.

00:31:25.420 | Now, I want to be very clear.

00:31:26.460 | I am not pushing supplements.

00:31:27.900 | I'm just pointing you towards some things

00:31:30.140 | that have been shown in peer-reviewed studies

00:31:32.700 | to have some benefit.

00:31:33.760 | The first one is magnesium.

00:31:37.220 | There are many forms of magnesium,

00:31:38.720 | but certain forms of magnesium can have positive effects

00:31:42.100 | on sleepiness and the ability to stay asleep,

00:31:44.240 | mainly by way of increasing neurotransmitters like GABA.

00:31:49.140 | There are a lot of forms of magnesium out there,

00:31:50.940 | but one in particular is magnesium threonate,

00:31:53.620 | T-H-R-E-O-N-A-T-E,

00:31:56.440 | which you have to check to see if this is right for you.

00:31:59.740 | Check with your doctor.

00:32:00.820 | The other thing is theanine,

00:32:02.600 | T-H-E-A-N-I-N-E,

00:32:08.480 | theanine.

00:32:09.780 | 100 to 200 milligrams of theanine, for me,

00:32:12.140 | also helps me turn off my mind and fall asleep.

00:32:15.020 | Interestingly, theanine is now being introduced

00:32:17.420 | to a lot of energy drinks

00:32:19.380 | in order to take away the jitters

00:32:21.600 | that are associated with drinking too much caffeine

00:32:23.980 | or with some other things that are in the energy drinks.

00:32:26.120 | So just a consideration.

00:32:28.340 | Again, I'm not here to tell you what to do or not do,

00:32:30.300 | but just want to arm you with information.

00:32:32.500 | The thing about theanine and magnesium is taken together.

00:32:38.200 | They do, for some people,

00:32:39.800 | they can make them so sleepy and sleep so deeply

00:32:42.600 | that they actually have trouble waking up in the morning.

00:32:44.380 | So you have to play with these things and titrate them

00:32:46.540 | if you decide to use them.

00:32:47.640 | Again, if you decide to go this route.

00:32:49.180 | I would not start by taking supplements.

00:32:51.460 | I would start by getting your light viewing behavior correct

00:32:54.820 | and then think about your nutrition

00:32:56.400 | and then think about your activity

00:32:57.700 | and then think about whether or not you want a supplement.

00:33:00.160 | We already talked about melatonin earlier.

00:33:02.260 | There's another supplement that could be quite useful,

00:33:04.220 | which is apigenin, A-P-I-G-E-N-I-N,

00:33:08.100 | which is a derivative of chamomile.

00:33:10.060 | 50 milligrams of apigenin also can augment

00:33:13.780 | or support this kind of creation of a sleepiness

00:33:17.540 | to help fall asleep and stay asleep.

00:33:19.460 | As a important point,

00:33:21.680 | apigenin is a fairly potent estrogen inhibitor.

00:33:25.340 | So women who want to keep their estrogen levels high

00:33:29.080 | or at whatever levels they happen to be at

00:33:31.020 | should probably avoid apigenin altogether.

00:33:33.540 | And men take that into consideration as well.

00:33:37.140 | Men need estrogen also.

00:33:38.380 | You don't want to completely eliminate your estrogen.

00:33:40.740 | That can create all sorts of bad effects

00:33:42.420 | on libido and cognition, et cetera.

00:33:45.020 | So apigenin in some people

00:33:47.040 | is going to be a pretty strong estrogen inhibitor.

00:33:48.880 | So keep that in mind.

00:33:50.560 | So thank you so much for your time and attention.

00:33:52.500 | And above all, thank you for your interest in science.

00:33:55.260 | [upbeat music]

00:33:57.840 | (upbeat music)

Essentials: Master Your Sleep & Be More Alert When Awake

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