- Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. I decided that we would hold office hours. Office hours in the university setting are when students come to the professor's office, or you meet outdoors on campus, or in the classroom, to review the material and questions from lecture in more detail.

Now, unfortunately, we don't have the opportunity to meet face-to-face in real life, but nonetheless, you've been sending your questions, putting them in the comments section on YouTube, et cetera, and I've prepared a number of answers to the questions that have shown up most frequently. Now, in order to provide context and structure to the way that we will address these questions, I've arranged the science and science-based protocols that relate to various aspects of life, such as mood, exercise, sleep, waking, anxiety, creativity, et cetera, into the context of a day.

Selecting the unit of a day in order to deliver this science information and protocols is not a haphazard decision on my part. It's actually the case that every cell in our body, every organ in our body and our brain is modulated or changes across the 24-hour day in a very regular and predictable rhythm.

And so selecting the unit of the day is not just a practical one, but it's one that's related to our deeper biology. So let's talk about how to apply quality, peer-reviewed science to your day, and how to optimize everything from sleep to learning, creativity, meal timing, et cetera. I'm going to do this in the context of my day and what I typically do.

I tend to wake up sometime around 6:00 AM, 6:30. The first thing I do after I wake up is I take the pen that's on my nightstand and the pad of paper on my nightstand, and I write down the time in which I woke up. The reason for writing down what time I wake up is because I want to know what's called my temperature minimum.

I don't care what my actual temperature is. I care when my lowest temperature is. And I know that that lowest temperature is approximately two hours before my average wake-up time. The second thing I do after I wake up is to get into forward ambulation, which is just nerd speak for taking a walk.

There's a phenomenon whereby when we generate our own forward motion, forward ambulation, visual images pass by us on our eyes, so-called optic flow. Experiencing visual flow has a powerful effect on the nervous system. The effect it has is essentially to quiet or reduce the amount of neural activity in this brain structure called the amygdala.

And many of you have probably heard about the amygdala for its role in anxiety and fear and threat detection. And indeed, the amygdala is part of the network in the brain that generates feelings of fear and threat and anxiety. It does a bunch of other things too, but that's one of its primary functions.

Forward ambulation, walking or biking or running, and generating optic flow in particular, has this incredible property of lowering activity in the amygdala and thereby reducing levels of anxiety. That walk is a particularly important protocol each day because it really serves to push my neurology in the direction that I'd like it to go, which is alert, but not anxious.

I want to have a high degree of focus and alertness because I'm soon going to move into a bout of work. I need to lean into the day. So in order to do that, I make sure that the walking is done outdoors. I do it outdoors because I also want sunlight in my eyes.

Getting sunlight in your eyes first thing in the morning is absolutely vital to mental and physical health. Even if there's cloud cover, more photons, light information are coming through that cloud cover than would be coming from a very bright indoor bulb. So getting outside for a 10 minute walk or a 15 minute walk will basically ensure that you're getting adequate stimulation of these neurons in the eye that are called the melanopsin, intrinsically photosensitive ganglion cells.

These are neurons that convey to the brain that it's daytime and it's time to be alert. And it sets in motion a huge number of biological cascades within every cell and organ of your body, from your liver, to your gut, to your heart, to your brain. Early in the day, we experience a natural and healthy bump in a hormone called cortisol and promotes wakefulness.

It actually promotes a healthy immune system. It's very important that that pulse of cortisol arrive early in the day. That pulse of cortisol is going to happen once every 24 hours, no matter what. It's going to happen and you get to time it. How do you time it? Primarily by when you view bright sunlight.

You can combine it with the forward ambulation with the walk and the optic flow that I talked about before. And that's what I do each morning to generate a sense of alertness in my body and brain to generate a sense of calm yet alert. So now we have our first protocol, which is to write down the time of day that you wake up.

The second protocol is to take a walk first thing in the morning. And the third protocol is woven in with that walk, at least for me, which is to get that sunlight exposure. I'm a big believer based on quality peer review data, that hydration is essential for mental performance.

As many of you know, neurons require ionic flow. What that means is neurons need sodium. They need magnesium and they need potassium in order to function. We do tend to get dehydrated at night. I try and make sure that I'm hydrated early in the day before I begin any work.

So I make myself drink this water with a little bit of sea salt. How much sea salt, if you really want to get detailed, I suppose it's about half a teaspoon. It's not much. At that point, I start craving caffeine, but I don't drink that caffeine yet. I purposely delay my caffeine intake to 90 minutes to 120 minutes after I wake up.

The reason I delay caffeine is because one of the factors that induces a sense of sleepiness is the buildup of adenosine. The buildup of adenosine accumulates the longer we are awake. When you wake up in the morning, your adenosine levels are likely to be very low. However, caffeine is an adenosine blocker.

It's actually a competitive antagonist for you aficionados. It sort of parks in the receptor that adenosine normally would park at and prevents adenosine from acting on that receptor. That's why you feel more alert. The reason for delaying caffeine intake 90 minutes to two hours after waking is I want to make sure that I don't have a late afternoon or even early afternoon crash from caffeine.

One of the best ways to ensure a caffeine crash is to drink a bunch of caffeine, block all those adenosine receptors, and then by early or late afternoon, when that caffeine starts to wear off and gets dislodged from the receptors, a lower level of adenosine is able to create a greater level of sleepiness.

Delaying caffeine in 90 minutes to two hours optimizes this relationship between adenosine and wakefulness and sleepiness in a way that really provides a nice consistent arc of energy throughout the day and brings energy down as I'm headed toward sleep and falling asleep. My primary objective early in the day is to get into a mode of being focused yet alert so that I can get work done.

I found that the best way for me to achieve that state is through fasting. So I don't eat anything until about 11:00 AM or 12:00 noon. Fasting increases levels of adrenaline, also called epinephrine in the brain and body. And when our levels of epinephrine and adrenaline are increased, we learn better, we can focus better.

You don't want epinephrine, AKA adrenaline, too high. That feels like stress and panic. You get jittery, you can't focus. But in its optimal range, adrenaline really provides a heightened sense of focus and the ability to encode, meaning bring in and retain, remember information. Next, I want to talk about what I'm doing while I'm working.

A couple of things for optimizing workspace that are grounded in neuroscience and physiology. I've talked before about the fact that when our eyes are directed upward, it creates a state of heightened alertness. And this has a relationship to the brainstem neurons that create alertness and their control over the muscles of the eye, and believe it or not, the eye lids.

The point here is that you can optimize your workstation in a physical way that leverages this aspect of the visual system and your level of alertness. Try and position your screen or your tablet, whatever device you happen to be working on, at least at eye level and ideally slightly higher.

Most people are looking down at their computer or tablet or are angling their eyes at their screen at about 30 degrees. When we look down, when our eyelids are slightly closed, it tends to decrease our levels of alertness and increase our levels of sleepiness. So we're now at the description of my day and these protocols in which I would do a 90 minute bout of work.

Now why 90 minutes? Well, the brain is going through these 90 minutes, so-called ultradian cycles throughout the entire day and night. Every 90 minutes, we shift over from being very alert to being less alert and then back to alert again. Here's how it works. At the start of one of these 90 minute ultradian cycles, my brain is not quite engaged in whatever it is I'm trying to do, but I set a timer for 90 minutes and I try and get a strong bout of work done inside of that 90 minutes with the full understanding that the entire 90 minutes is not going to be uniform in terms of my ability of focus.

So the goal is to get into what I call the tunnel, to really get into a tunnel of quality work. The brain loves that state, but it's very hard for many of us to access. My phone is absolutely off. It's not on airplane mode. It's absolutely off during this time.

In addition, I use low level white noise. White noise, which is essentially all frequencies of sound. We're all frequencies of sound that we can perceive mixed up kind of randomly. There's no structure to it. Turned on at a low volume puts the brain into a state that's optimal for learning and workflow.

So everything about this 90 minute block from the low levels and white noise to the position of my computer, how I'm standing and where my eyes are positioned is geared towards putting me in this tunnel of work. And I have to say that while it can be a challenge to try and achieve this state and this tunnel of work, some days you start to get kind of addicted to it.

It feels really good. It's like a workout for the mind. And it is something that as you exit that 90 minutes, you really feel like you've accomplished a lot because often you have, and it just feels deeply satisfying. And I'm convinced that that's because of the release of neuromodulators like dopamine and the norepinephrine that's circulating in your system.

And I want to be clear that I'm not perfect about this 90 minutes. Occasionally I get drawn away, but I really try and achieve this most, if not every day that I'm alive, because for me, that work session is kind of holy. There's a powerful way in which you can place the timing of this 90 minute work bout in an optimal way.

You have access to a very important piece of data that dictates when this bout should start more or less and when it should end. That piece of data is your temperature minimum. If you're somebody who wakes up on average at 7 a.m., well, then your temperature minimum is 5 a.m.

you can be reasonably sure that your best work is going to be done anywhere from four to six hours after your temperature minimum. How do I know this? How do I know this relationship between temperature minimum and focused cognition? Well, temperature minimum defines the trough, the nadir, as they say, of your temperature across the 24-hour cycle.

And immediately after that, your temperature will start to rise. That temperature rise is actually what triggers the initial cortisol release that you experience and wakes you up further. And then of course, that sunlight that you're getting is going to further enhance that healthy release of cortisol. That cortisol will then provide fuel, if you will, for that increase in temperature.

And your body will continue to increase in temperature throughout the day toward the afternoon. What you're trying to do in this idea of optimizing this 90 minute work bout to a particular time of day is catch the portion of the steepest slope of that temperature rise. So if you're somebody who wakes up at 8 a.m.

each morning, your temperature minimum is 6 a.m., chances are you're going to want to start this work bout somewhere around 10 a.m. or 11 a.m. Now, some people wake up and feel very alert first thing in the morning. They can really do their best work first thing in the morning.

Please, if that's you, continue to do that. Leverage that time. Use that time. But if you're somebody who struggles to find focus, definitely let your physiology and this rise in your body temperature support your efforts to focus, rather than trying to do your best work at times of day when your physiology is actually directing your body and your brain toward defocus and towards being more lethargic.

It just is setting yourself up for success when you try and capture this rising phase of your temperature. Data going back to the 1990s supports the idea that physical movement of particular kinds can support brain health and brain function, both in the immediate term and in the long term.

So after I've finished a bout of work, this 90-minute bout of work, I force myself to do some sort of physical exercise that is going to be supportive of my brain health and brain function and organ health and bodily function in general. Now, there are various forms of physical activity or what we call exercise, but those can generally be batched into two categories.

First is strength and hypertrophy work. So physical movements that are designed to make you stronger and or make your muscles larger. There's also endurance work, physical exercise and movements that are designed to allow you to do more work over time or to extend the amount of time that you can do work of any kind, both physical and mental.

The data all point to the fact that working out hard for longer than an hour can actually be detrimental because of the way that it raises cortisol, and cortisol can be a good thing if it's appropriately timed and in the appropriate low levels, but you don't want to have your cortisol levels up throughout the day or have big spikes of cortisol repeatedly.

So keeping workouts relatively short can definitely help with that. Endurance work and strength training or hypertrophy training done in combination, meaning not necessarily in the same workout, but done across the week, is immensely beneficial for the production of things like brain-derived nootrophic factor, for limiting inflammatory cytokines like IL-6, for promoting anti-inflammatory cytokines like IL-10, provided that exercise is of the proper duration and that it's not so intense that you're actually creating damage to the various systems of the body.

What about the structure of the actual workouts? Well, approximately 80% of the resistance training you do should be resistance training that doesn't go to what they call failure, where you can't actually move the resistance anymore. The other 20% can be of the higher intensity to failure type training. That 80-20 rule of less than failure and work to failure in the resistance exercise regime can be transported or translated to the endurance exercise portion by focusing on that thing that we're familiar with, which is the burn.

When we're running hard or cycling hard, we'll experience a kind of burning of the muscles that's associated with the lactate system. And actually, the lactate system is its own form of fuel for the brain. And so there's increasing interest in generating the lactate or pushing past that lactate threshold for small portion, 20% or so of endurance work in order to support brain health and function.

So on any given day, I finish that work block and I train. I do some sort of resistance or endurance training. I put those on alternate days or different days rather. So we've now talked about the arc that spans all the way from waking to a morning bout of focused work to physical training.

I have not mentioned ingesting anything or nutrients. One of the most common questions I get are, what should I eat for my brain? Well, ironically enough, one of the best things you can do for your brain is to not eat. But of course, we all have to eat sooner or later.

So let's talk about food timing first. As I mentioned, I eat my first meal sometime around noon, plus or minus an hour. However, the volume of food is also important. If you eat a large volume of anything, because it diverts blood to your gut, you will feel lethargic and you will have less blood going to your brain.

That seems like a simple and trivial fact, but if you want to be able to think, you can't ingest large volumes of anything into your gut. So for lunch, I do emphasize slightly lower carbohydrate or low carbohydrate intake for the simple reason that adrenaline and dopamine and their associated neuromodulators are going to support alertness.

So for me, I fast up until about noon. Then I eat a lunch that consists of some sort of protein thing, like some meat or some chicken or some salmon and some vegetables, et cetera. And if I've exercised previously, which I do, as I mentioned, five days a week, then I will ingest some starches.

I'll ingest some bread or bread, excuse me, or rice or oatmeal and butter and nuts and things like that. But I will keep the total amount of carbohydrate a little bit on the low side. Or if I haven't trained, I won't have any carbohydrate at all. Not because I'm ketogenic, but because starches cause the release of serotonin in the brain and lend themselves to a state of sleepiness.

Now, what about components of foods that are not about alertness, but are about mood? We did an entire episode on mood and food. And it's very clear based on now dozens of studies that ingesting sufficient levels of omega-3 fatty acids is going to support healthy mood and even can act as an antidepressant.

Ingesting at least 1,000 milligrams per day of the EPA form of essential fatty acid is as effective as prescription antidepressants in relieving depression. And if you're somebody who requires prescription antidepressants, Prozac, Zoloft, et cetera, it can allow people to take lower doses of those medications. A key aspect to the midday meal, if you want that meal to benefit you, is to take a brief walk afterwards.

It turns out that brief walks of five to 30 minutes after ingesting food can accelerate metabolism and actually can accelerate and improve nutrient utilization, which is essentially the same as metabolism. But nonetheless, that's something that I do after I finish my noon meal. I do force myself to stand up and go outside and take a brief walk.

That also gets me again into optic flow. It also has another benefit, which is that I am giving my brain and thereby my body more information about light and time of day, which is always better than less information about light and time of day. A key protocol for sleep health and wakefulness and metabolism and hormone health is viewing light in the afternoon.

So here's the reason for doing this. As we progress into the evening hours, there's a phenomenon where our retina, our eyes become very sensitive to light, such that if we view bright lights or even not so bright lights between the hours of 10 p.m. and 4 a.m., that is strongly disruptive, very disruptive for our dopamine production.

It can really screw up our sleep. But if you can get outside and see the sun as it arcs down, or if you can't see the sun directly, get some sunlight in your eyes in the afternoon hours, so maybe 4 p.m.-ish, what it does is it lowers the sensitivity of your retina in the late evening hours, which allows you to buffer yourself against the negative effects of bright light later at night.

Now, we haven't talked too much about melatonin, but melatonin is a hormone that is inhibited by light. Melatonin is the hormone that allows you to fall asleep easily. Now, I'm not talking about supplementing melatonin. I'm talking about melatonin that you naturally produce from your pineal. So, the protocol is very simple.

Get outside in the afternoon or evening for 10 to 30 minutes. Take your sunglasses off, so get that afternoon light. So, what you'll probably notice is that the optimal protocols for optimizing your brain and body health, and performance, and sleep, etc., are actually really simple. But just because they're simple does not mean that they are not powerful.

In fact, they are very powerful because they leverage the most powerful technology that exists, which is your nervous system. What we are talking about today are really basic things that we can all do that can steer our neurology and our biology in the directions that are going to support workflow, that are going to support hormones, that are going to support brain function.

So, at some point in the evening, I eat that thing that we call dinner. And while it feels sort of strange to talk about my dinner, the reason I want to talk about my dinner and what I eat for dinner is that, for me, dinner, of course, is about eating, but also about optimizing the transition to sleep.

So, my dinner generally is comprised of things that are going to support rest and deep sleep, and that means starchy carbohydrates. It's absolutely clear that one of the major ways that we can increase serotonin, which helps in the transition to sleep, is by ingesting starchy carbohydrates. So, my dinner is carbohydrates and some protein, so maybe some chicken or fish or something like that, maybe some eggs, or sometimes just pasta or just rice and vegetables.

And that's because I enjoy those foods, but also because I want to increase the amount of serotonin in my brain so that I can actually fall asleep that night. Many people who are on low-carbohydrate diets struggle with falling and staying asleep, and that's because it's hard to achieve heightened levels of serotonin, which are necessary to enter sleep.

I should also mention that melatonin and serotonin fall in the same pathway. They are related hormones and neuromodulators. Essentially, what we're talking about is a system that's biasing us towards rest and relaxation as opposed to wakefulness. You might ask, "Well, can't I just take serotonin? Can't I just take 5-HTP or a precursor to serotonin or tryptophan?" And indeed, you can.

However, many people, including myself, find that when they supplement with serotonin in the evening or at night, that can cause problems in the architecture or the structure of sleep. It can cause a lot of people, including me, to fall asleep very fast, sleep very deeply for three or four hours, and then wake up and have a terrible time falling back asleep.

And that effect, at least for me, can last several days. It's really disruptive. So I don't like to supplement with anything that is directly dopamine or a precursor to dopamine at any time, or directly serotonin or a precursor to serotonin. Rather, there are other things that can enhance the transition to sleep safely, which we will talk about in a few minutes.

But the evening meal consists largely of carbohydrates for that specific purpose of generating a sense of calm. And of course, carbohydrates are delicious. And because I'm doing some physical training, and presumably you are as well, or I hope you are, because it's so beneficial to one's health, that's also going to replenish my glycogen stores, which is one of the primary fuel sources for moving one's muscles and moving around and doing exercise, as well as for the brain and for cognitive function.

So let's talk about sleep and how to access sleep. One way to do that is to leverage the drop in temperature that's necessary to fall and stay asleep. So as I mentioned earlier, in the early parts of the day after waking, our body temperature is rising, and that continues throughout the day.

And then sometime late in the afternoon, our temperature peaks, and then it starts to drop. That drop in temperature of one to three degrees is vitally important for us to be able to fall asleep easily. One way that we can decrease our transition time into sleep is to accelerate that drop in temperature.

And one way to accelerate that drop in temperature, somewhat counterintuitively, is to use hot baths, hot showers, or if you have access to one, a sauna. Now this is counterintuitive, but actually if you are to get into a sauna or a hot shower or a hot bath and then get out, your body is going to engage particular mechanisms for cooling itself off that are going to allow you to drop your temperature more quickly and fall asleep more easily.

It is absolutely true that keeping the room very dark is beneficial. The other thing is keeping the room cool. The reason keeping the room cool is useful for getting into and staying asleep is that throughout the night, there are phases of sleep where you are paralyzed, so-called REM sleep.

That's a healthy paralysis, presumably so you can't act out your dreams, but there are portions of the night where you can move. And one of the more important movements that you do in the middle of the night is put your hand out or your foot out, or you take your face out from under the covers as a means to cool yourself.

You're actually allowing cooling of the body through what are called AVAs. Arteriovenous astimoses is the technical name that are in the palms, the upper half of the face and the bottoms of the feet. Now, there are things that one can take to enhance the transition to sleep. Three compounds that can be very beneficial for aiding the transition to sleep and for which there are wide safety margins, although please do check with your physician before taking anything, are specific forms of magnesium, something called apigenin and theanine.

Magnesium comes in many forms. Magnesium threonate, that's T-H-R-E-O-N-A-T-E, threonate, and magnesium biglycinate, have transporters that allow them to cross the blood-brain barrier more readily than other forms of magnesium. And there within the brain, they promote the release of a neurotransmitter called GABA, which is an inhibitory neurotransmitter, which shuts off the forebrain to some extent.

It doesn't shut off completely, but it essentially shuts down thinking, rumination, planning, and what we call executive function. So for many people taking 300 to 400 milligrams of magnesium biglycinate or magnesium threonate 30 to 60 minutes before sleep can aid them in falling asleep when coupled with apigenin and theanine provide a sort of synergy or a sleep cocktail that seems to be very effective in aiding the transition to sleep.

So apigenin is the substance that's found in chamomile and 50 milligrams of apigenin taken 30 minutes before sleep can act as another way to shut off the forebrain and reduce rumination, reduce anxiety, and allow people to fall and stay asleep. And then the third compound is theanine, T-H-E-A-N-I-N-E. Theanine is a compound that can also increase GABA, but also increases activation of something called chloride channels.

Chloride channels are another way in which neurons lower their levels of activity. So magnesium threonate or biglycinate, apigenin, and theanine in combination can be very effective for aiding the transition to sleep. Now, what if you wake up in the middle of the night? This is a very common occurrence, and there are two general themes around waking up in the middle of the night that one can use tools to counteract.

The first theme is if you're somebody who is tired in the evenings and you're kind of pushing yourself to stay awake. So you're going to the party or you're pushing yourself to study your work when, in fact, you'd like to get into bed at 8, 30, or 9, and then you're falling asleep around 10, 30, or 11, and waking up at 2, 30, or 3 in the morning and you can't fall back asleep.

Chances are that your melatonin pulse was initiated early in the night. So that melatonin pulse started probably around 8, 30, or 9, but you're staying up. You're battling that melatonin. You may not like this advice, but one of the things that you can do to offset that is to simply go to bed earlier.

The other thing is many people wake up in the middle of the night because of anxiety or because they have to use the restroom. It's perfectly fine to flip on the lights, but keep the lights dim. But if you flip on those lights, try and flip them off as soon as possible and try and get back into bed.

So now we've essentially traveled around the clock, so to speak, from the time where one wakes up until the time they get to sleep, maybe wake up, get back to sleep, etc. I want to emphasize that although people's schedules vary, most people are doing more than one or two work bouts per day.

And indeed, I'm doing more than one or two work bouts per day. I really emphasize that morning 90-minute work block because I think most people would agree that there's a portion of each day in which we need to do the hardest thing or the most important thing or the thing that demands the most of our cognitive self.

I position that early in the day, and I position everything around that in order to ensure that it happens and that it happens with the highest degree of efficiency, even though that morning 90-minute work block is so vital. Of course, there's a second work block. So combined, that's just three hours of focused work, which may not seem like a lot.

But if you were to dissect your day and kind of look at the arc and structure of your day, I'd be willing to bet that if we added up the total period of time in which you were in deep work, really focused, dedicated work, that it would probably amount to about three or four hours.

And of course, throughout the day, there are other things happening outside of those 90-minute work blocks. I'm checking my text messages, I'm checking my email, I'm responding to various demands, I'm working and tending to life. So while I've carved some boundaries or delineated some boundaries around those work blocks, and I'm certain that if you do too, you will benefit from them, of course, please adapt and modify what I've described today in ways that best serve you and your schedule.

What I've tried to do is provide you scientific support, specific protocols and regimens, because people are always asking me for more specificity and detail, and an example of one way, just one way, in which these various tools and protocols that are grounded in science could be leveraged in one's own life.

And last but not least, thank you for your interest in science. Thank you for your interest in science.