Welcome to the huberman Lab podcast, where we discuss science and science based tools for everyday life. I'm Andrew huberman, and I'm a professor of neurobiology and Ophthalmology at Stanford school of medicine. Today. I have the pleasure of introducing. Dr. Samaram guitar, as my guest on the huberman. Lab podcast. Dr. Hatake are is the chief of the section on light and circadian rhythms at the National Institute of Mental Health in Bethesda, Maryland, dr. Hunt.
Our has many important discoveries to his name. He was one of a handful of groups that discovered the light sensing neurons in the eye that set the circadian clock. This is a fundamental discovery made in the early 2000s that has led to an enormous number of additional discoveries on how light, regulates our sleep, our immune system, our mood mental health metabolism, feeding, and many other important processes.
If ever there was somebody who understands how all of these processes interact and can inform best practices for our daily behaviors. It's dr. Hurt our during our discussion today, dr. Hunt. Our answers questions that are absolutely essential for us to know about our health. And wellbeing, for instance, how to align our sleep schedule with our activity schedule such as exercise and how to align light activity and exercise with our feeding rhythms. He
And say new model of how light activity and feeding rhythms converge to support Optimal Health. And when those are not aligned correctly, how our mental and physical health can suffer. It's a discussion that is Rich with scientific mechanism made clearly, of course, so everybody can understand as well as specific protocols to deal with shifts in day length, shifts in activity. And in order to optimize sleep metabolism and well-being of various.
Kinds, I learned so much from Samurai as I always do. He is an absolute wealth of knowledge on all things related to light and circadian, rhythms physiology and Neuroscience. I don't think you'll find anyone else as knowledgeable about these topics as Samer. And so, I'm delighted that he joined us here on the podcast, to share this information. Before we begin. I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is however, part of my desire and effort to bring zero cost to Consumer information about science and science related tools to the
No public in keeping with that theme. I'd like to thank the sponsors of today's podcast. Our first sponsor is rokka rokka makes eyeglasses and sunglasses that are of the absolute highest quality. I've spent my career working on the science of the visual system and I can tell you that, one of the things that our visual system has to contend with is adjusting. So that when we go from a very bright area to a dim or shadowed area, we can still see things. Clearly, Roka eyeglasses and sunglasses were designed with the science of the visual system in mind. And so they make those transitions seamlessly.
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Too fast in the early part of the day. I tend to eat kind of low carb ish through the middle of the day. And then, in the evening, I eat carbohydrates. That's what works best for me and allows me to feel alert all day long and to sleep really well at Night. Magic spoon is a terrific snack for me because it tastes terrific. It's got some sweetness, but it doesn't take me out of that state that I want to be in during the day where i'm sort of Quito. Wish. I would say, I'm not actually in ketosis, but I'm following more or less a low-carb diet during the day, which keeps me alert. So, either fasting or low carbon.
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Work on how light impacts mood, learning, feeding, hunger, sleep, and these sorts of topics. So just to kick the ball out onto the field. So, to speak, how does light impact the way we feel? So when I get up in the morning, I have the opportunity to interact with light in certain ways or to avoid light. In certain ways. I have the opportunity to interact with sunlight, or with artificial light. Maybe you could just weighed us into
What the relationship is between light and these things, like mood and hunger, Etc.
Sure. So, I mean you do appreciate the effect of light for vision. So when you wake up in a beautiful area, beautiful ocean light is essential the sunrise, the sunset, Blue, Sky, beautiful mountains. So that's your conscious perception of light but light has a completely different aspect that is independent of conscious Vision or image.
Or
make functions, and that's how it regulates many important functions in your body. I think the best that is well, studied and well-known is your circadian clock and the word circadian comes from the word Circle, which is approximate and DNA's day. So it's an approximate day. Why is it an approximate day? Because if I put you or any other human being who have enormous circadian clock in a constant conditions, with no information about feeding time about sleep time.
About what time it is outside. You still have a daily Rhythm but it's not exactly, 24 hours. So it will shift out of the solar day because it's not exactly 24 hours and hence, the name
circadian. So just ask a quick question about that. When you say you have, this is about 24-hour Rhythm. How does that Rhythm show up in the tissues of our body?
Great. So great question. So it shows up at every level that we know, we studied it shows up at the level of the cell. It shows up.
At the level of the tissue and it shows up at your behavior. The most obvious for you is your sleep-wake cycle, you sleep, and you're awake and sleep at the 24-hour rhythms. And if you measure the sleep-wake cycle of a humans, who are maintaining constant conditions, you will see that the period length of the Sleep Rhythm on average is more than 24 hours in a human's is twenty four point two hours. So, you'll be drifting point two hours every day out of the solar day. If you don't get the sunlight, so the, the Sun,
Light adjust that approximate data, an exact day. So now your behavior is adjusted to the light dark environment or the solar
thing. Okay. So if I understand correctly, if I were to go into a cave, yeah, or I were to be in constant light. Yeah, and I didn't close my eyes in constant light that I would still sleep in one coherent bout. Yes, and I would still be awake for more or less one coherent bout maybe a now. But the total duration of
My day. So to speak would be a little bit longer than 24 hours -. But if I'm in in a condition, like most people are, where the sun goes up, when the Sun goes down. And I have some understanding of that sunrise and
sunset here. Then have to have the understanding. You don't have to have conscious understanding. You have the detection, right? So, circadian photo entrainment is the word. We use in training the circadian clock, to the for Tech environment is completely subconscious. You're not aware of it. It's not like
Vision where or image forming where you actually know what you're looking at. So it's all hypothetical make. It's part of the brain that is not consciously driven. So you actually do not know when it happens or it doesn't happen. And that what we'll get into and I tell you, why light affects your mood and why sometimes people don't know how to deal with like to improve their mood, for
example. Okay. So this is a subconscious Vision. Yes. Okay. Before you tell us about how light impacts mood. I'm curious. What is the relevance?
Of adjusting this clock from little bit longer than 24 hours to 24 hours. I mean, it seems like a small difference, 24 hours, and 40 minutes or 24 hours. Like what? What's, what's the relevance? I mean, why should we care about that? Short diverse?
So let's do the math. If you shift out point two hours a day in five days, you shifting out one hour. So you're literally one hour off in your social behavior in five days in 10 days, your two hours off. And if you're an organism, that is living in the
The wild shifting out of the right phase of the cycle. You could either Miss food or you could become food. So it's really essential for survival. I think it's one of the strongest aspect of survival for animals to have the anticipation and the adjustment to the solar
cycle. And for humans as well, when you say animals, I'm assuming that applies to us. Yeah, I see. So even though it's just a short bit longer than 24, if you if that accumulates over days, then you could find.
So very much out of phase with the rest of your your species essential.
Let's say it's point two hours. So in five days is one hour in 25 days. It could be five or six hours. It you could be in New York and you're feeling as if you traveled from New York to London, so you will be having jet lag in New York, even though you didn't do a jet lag travel. So it's very important for the adjustment. And if we have time, maybe we could talk about why this is important for seasonality. Because also
It allows animals to anticipate the change in season and the more you're high in the North or the South, the more, that these weather changes occur, very harshly and you have to be ready for them and that happens in us as well.
I will definitely get into seasonality. Okay, so we've got this subconscious Vision. That aligns us with the turn of the Earth.
How does that work? What's the, what is the Machinery? That allows that to happen? And how does that? Machinery work? Yeah, so
we know we knew that in mammals including us. We are mammals humans that the eyes are required for this function. So if humans are born without eyes or the optic nerves are damaged, humans are not able to adjust to the solar cycle. So we know that the eyes are required and since we thought we knew about the ice a lot.
For 2000. We thought we said before, the year
2000 for the years. Yes. We thought it's these photoreceptors in your retina that allow you to see. So in the human retinas, there are two types of photoreceptors. They are called rods and cones because of their shapes. And these rods and cones, simply take the photon energy, which light is made off and they change it in a way to an electrical signal. That allow us to build the image of the environment in our cortices.
Consciously
consciously in this situation, because this Vision, right? This image forming Vision. It's a, it's a visual cortex and Association associative cortices, which allow you to build conscious perception of the environment. However, people have found including me, or with the work of David person and Ignacio, prevent sure that there is a subset of ganglion cells. The ganglion cells are the cells that leave the retina their accent, leave the retina and project to the brain. So these worth of sport to only
Relay rod and Cone information from the light environment to the brain. We found that a small subset of these ganglion cells are themselves photoreceptors that were completely messed in the retina. And these are the photoreceptors that real a light environment, subconsciously to the areas in the brain that have. And how's the circadian clock? Or the Circadian pacemaker? Which adjust all the clocks in our bodies to the central brain clock. That allows them to entrain?
To the 24-hour, light-dark cycle.
Incredible. So, in the year as I recall, because I was a graduate student at the time in the year 2000. There was this Landmark discovery made by you. We could prevent CEO, David person and others that these cells exist, that can communicate day and night information to the brain. Yeah. In this very small subset of cells since then I've heard, but maybe you can confirm or refute that this system that connects the Ides to the rest of the brain.
Is actually the most ancient form of vision that this is probably the form of vision that some early version of human beings had before. They had pattern Vision before they could see colors and shapes and motion and all that. And that the the that the same cells that perform. This role are actually similar to insect eyes. I think I heard David Burson. Say once that we actually have a little bit of the fly, I in our, I what's he talking about. Yeah,
so it's really interesting actually, because
Was these same ideology sees we discovered they contribute a little bit to image formation and now work from Tiffany Schmidt specifically have proven that they do contribute to image forming functions, but they contribute to very limited aspect of image formation. So it fits your hypothesis. That these are an ancient photoreceptors. The other thing that adds to that hypothesis is that they are expressed in cells that don't have any modification that make them look like photos.
So out the photoreceptors that I told you about that are important for vision image formation. They have very specialized structures that allow them to pack these structures with photopigments. These are the photo detecting proteins. So they could detect a high sensitivity of photons that pass through them. These IP addresses, don't have these new photoreceptors don't have these specialized structures. So they just really need a lot of light at the
Time. We thought they need a lot of light to be activated. So that's why we think they are ancient and that's why I think they adjust to ancient functions that are as important as regulating your body circadian, clock to the solar environment, the solar day or two the light-dark
cycle. So you mentioned IP rdcs intrinsically photo sensors. So these are cells that connect the eye, the brain that behave, like photoreceptors essentially. And then you mention melanopsin, which is the actual pigment that
It's the light into the electrical signal more or less and my understanding is that melanopsin was identified first in frog, Milano Force. Yes. So does that mean that we have like little pieces of frog skin in our eyes?
So honestly David versus say you have a fly in your eye because it sounds better. The more accurate I think is that you have a frog skin in your eye. It's not as catchy, but really melanopsin, really, the name. Melanopsin is from Milano, cytoxan, so, it's Miller.
An option because it was found in the Frog, melano sites, you know, the frogs can change their color depending on light and melanopsin drive this response. So, when Ignacio, prevents your first discovered, these options in frogs. Luckily, he was smart enough to see if they are expressed in the Frog. I they were expressing the frogeye and it would appears to be retinal ganglion cells, which I told you the one that connect the eye to the brain. He had the insight to go and see if they are expressed in the monkey. I and he found that they are all
Express in what appears to be retinal ganglion cells. And really that? What opened the field wide open, then, David person did the seminal experiment where he went to the brain, where the central oscillator. The the oscillator that drives circadian rhythm in the brain called the suprachiasmatic nucleus that has been known for many years to receive retinal imput and he labeled the cells that project there and then he found that even if you destroy rods and cones, you could get light responses from these cells. So you
You could imagine he nearly fainted when he saw that these cells can respond independent completely in the absence of Rod and Cone him.
Put. I'll never forget reading those papers and 2000 2001. I was at the meeting in DC. When you show Ignacio, Iggy, we call them Iggy showed this image of this. Basically what his frog, mallanna force in the human eye. And everyone's like, oh my goodness. This is the pain and I want to get into how light actually can control sir.
In rhythms, absolutely, but I think it's worth mentioning. Now that people who are pattern Vision blind. So people who cannot see and no conscious Vision, but have eyes, many of them still have these cells. These melanopsin intrinsically photosensitive cells and can essentially match or in train as we say, on to the light-dark cycle.
In fact, they possibly have no problems in circadian photo entrainment. They'll have a normal sleep-wake cycle, but they're totally blind, but they are totally image.
Blind and what's really interesting is that and the story I heard from truck-sized ler. So I'll give him credit that some of these people who are image brined. Usually, they get dry eyes and they give them a lot of pain and doctors used to think. Oh, that since they are image blind, and they're getting dry. Why don't you just remove their eyes, they not using them anymore. And the minute, they would remove their eyes. They start having cyclical sleep problems, indicating that. Now, they are not in training to the light-dark cycle and are having
Jet lag's when they're clock shifts through the light-dark
cycle. That's really interesting. And I hear from a number of blind people, you know, my various aspects of my job and they, a lot of them have issues with, with sleep. I think in part because they don't realize that they too need to see light at particular times of day or night in order to secure their schedule. Absolutely. Well, I think that's a perfect segue for us to talk about how light and viewing light can impact our sleep.
Wake rhythms, and then we move into some of the other ways in which light can impact other forms of bodily
function. Yeah. So I love the way you said it up because one of the most interesting and difficult aspect of trying to educate people about light effect on subconscious vision, is that it's subconscious. So we're all aware of what we think is intensity because we see the room. But you know, if you talk to people who know how to take photographs and stuff like that, they
That the intensity is varies greatly but our system because we have to see the same way in very bright conditions and very dim conditions will not very good at estimating and intensity consciously. So when you try to tell people about intensity, you really struggle because they think they know intensity is but they really
don't, you mean light intense light intensity.
So so that the calls themself have an incredible ability to adapt to different light conditions so you can see at all different conditions, other
Otherwise, it'd be a disaster, you know, if you don't change the setting on your camera and you go from inside the room to the outside, it becomes completely white. You don't see anything. So if the, your cones, don't adapt to the environment, then you're not going to be able to see in this room and in on the beach, right, but the problem is your your IP R GC is the cells that we talked about. They measure intensity pretty well. They really know what intensity is. They have a very good linear measurement of intensity. They don't
Adopt as well. They don't adapt actually that much, to be honest. So that tells you that subconsciously, the system is used to measuring light intensity in a natural environment because when you are now in the natural environment don't have, you know, industrialized lighting, then you know, your system is functioning very well. But now when we change these environments, we could really mess up ourselves. So you have to teach people how to understand intensity and
That's something that you have to explain to people, and I think I love to do it myself. I do it in. What is called the lowest amount of light required to allow you to see comfortably. So you have to do this as a fun experiment.
Okay. So explain to me how this goes and maybe we could break it up into the day into three or four parts. So let's say assuming that most people wake up in the morning, as opposed to night shift workers, Etc. We could talk about later but the wake up in the morning. So let's divide the day into quarters. What is it?
Is the proper way to interact with light in the first part of the day,
so I honestly think the easiest thing is waking up. Get as much light as you can into your eyes. Yeah, it's really nice. Your system is primed if you're in trained is primed to get light. The sun should be out most animals in the wild. They actually seem to track the sun. The sun has a huge influence on life on Earth is actually life on Earth is because of Sun. So that's
Easy in the morning when you wake up, you need light.
Okay. So what is the behavioral practice that you recommend? Does it? Let's say, somebody is in a condition where there's a lot of cloud cover. Yeah, is it important to get
outside? So I have to tell you the cloudiest day is going to be much more brighter than your room. You could ask any photographer a cloudy day unless it's really dark. Dark clouds. Usually cloudy days have much more right outside than inside the room even when you have good lighting inside the room, so I think
The outside is usually even when it's cloudy, you're going to get enough intensity to help you. Adjust your cycle to the
day-night cycle. So how long do you? These are general rules of thumb? But how long do you recommend? People
go out? Do it daily? You possibly need very few. Do it daily because you remember this thing is going to happen on a daily matter.
So it's the clock is tracking it on a regular
solutely. It's Photon. Counting is tracking. I would say 15 minutes. If you don't do it daily. You may want to increase it.
And we'll talk about when you travel what you could do. But but yeah, 15 minutes should be fun. You do it more. It doesn't hurt and
through a window. I was my understanding is that through window, it dramatically decreases, the amount of light energy. Can you do it depends
of how, you know, how thick the windows are, and how dark they are. So it but it's also nice to go outside and to feel the season sunglasses off. I don't use sunglasses. I
have. But you have the your Jordanian for pigment, you know, so yeah, whereas my eyes are very sensitive.
Yeah, but not
so I but I personally, you know, if I'm in the shade or if it's not incredibly bright, I tried to especially in the morning, but I'm also an early person. So we have to differentiate between early and you wake up. I wake up at 4:30 in the morning. The sun isn't it's not out yet. So it's
what do you do? You turn on artificial
light? I usually don't turn an artificial light because I know the Sun is going to come up eventually, but that's why I don't like the change in the timing that they do. You have what do you do
between 4:30 a.m. And 7 a.m.
Am. I mean
I just got my computer. I see. So possibly I get enough light but but in reality, I mean, as long as you let your body get the morning sunlight, which I think is really to me, and I, there is no evidence. But to me, this is, if you look at all animals, plants this morning, sunlight seems to be very important and I, you know, we don't have experiments to show it but I have a gut feeling that it has a huge impact on
humans. Will Jamie's icers Lab at
Sleeve. I was shown that these early morning, light flashes, can adjust the total amount of sleep. That one will get makes it easier to get up to sleep.
Absolutely. Okay, so and can write also did this beautiful camping experiments
that showed maybe to describe those because those are beautiful experience. They are
beautiful, expand. He took these, you know, college students that had the late onset of sleep and lick waking time. And then he said, let's go camping and just don't use any artificial light.
And you could go to sleep as as as late or, as early as you want and wake up as late as early and he found the huge shift in their sleep pattern, just by exposing him to the light-dark cycle. I mean, so
in a lasted and it lasts even after they came back. Exactly, two days of camping, reset the
Circadian seven days, but it lasted. Yeah, it's pretty amazing. Yeah, it's really
incredible. Okay, so, get bright light of some sort early in the day, ideally sunlight. Even on a cloudy day.
It's going to be absent brighter than indoor light. Oh, that's easy. Okay, so then and
the other thing that I would like to mention to people. If it few think it's very dim outside. Let's say it's very cloudy stay longer. So remember intensity is only one component. Duration is also important because remember that the Circadian system is not like the image system in the image system. You have to change every second because you looking at different objects, you have to change your perception, but for the Circadian system is trying to figure out, where am I in the
Day night cycle. So the more you give them the information, the better you are. So if it's very bright, you don't need a lot because it's clearly going to make you fire, like crazy. But if it's not bright, stay longer stay for one hour, you know, have your coffee outside or something like that. It's just going to help. But then you said something extremely
important, which is that this circadian system is trying to figure out when you are in time, exactly. Not where you are in.
So I said, where you are in time coming when you are.
Oh, no, I wasn't correct.
I just meant that it, I think fundamentally, that's the the incredible thing about the systems that you have this clock, this 24-hour clock in your brain, but it needs to be synchronized to the outside. So could we go a little deeper into this circadian? Setting behavior and come up with some general rules of thumb. So let's say it's a very bright day, extremely bright. Yeah, no clouds. Sun's out.
You said 10 minutes, 15 minutes
and I'll tell you if you're sensitive. Don't you don't even have to go in the sun. You could be in the shade. This is going to be so many photons out there in the shade is going to be perfect. You don't even have to see the sun. You don't have to have the son. You know, it's great for vitamin D. That's a different story. You could do this for your skin. And and you know, protect your skin. That's not my area of expertise, but for that effect on the Circadian system, as long as you're outside in the shade, and sunny day,
10 to 15 minutes should be ample
amount. Okay, and then let's, let's say it's kind of overcast, you know, it's not particularly bright or there's, you know, solid cloud cover but you know, the obviously the sun is out but your, it's not as bright. How long do you think it would take to set their
clocks, 10 to 15, should be sufficient? Stay for half an hour say for 45 minutes if it's very dark Rob. Yeah, stay for longer.
Okay, and if for some reason one finds themself very far north and it's very, very dense.
Cloud cover. How long and at what point should somebody consider using an artificial light source to mimic the sunlight?
Yeah, honestly, this is where we don't have a lot of information step because this is where we're going to discuss this maybe in more detail that if you put humans in artificial conditions, the Circadian system is very sensitive to light.
But in reality, in the Real Environment, light also is affecting other aspects that are independent of the setting of the Circadian pacemaker. Okay, and these, which we call the direct effect of light on mood, for example, so that is very hard to figure out what intensity, you need to use. And we haven't done enough experience because the system has been discovered, just recently, but I would say if you use bright light in the morning, and I mean, it's hard for me to give numbers it can get.
Complicated. But yeah, I mean if you're honestly if you're that far, north and you're in the winter and you want to get, make sure you don't use these light boxes, I would suggest that personally. But that's it.
I use, it's actually not designed for circadian setting, but I have a 930 looks light pad that I bought and I bought it. They're very affordable compared to the dawn simulating lives, you know, which are which are quite expensive. Frankly, and I put it there and so I
Just basically when I wake up in the morning, I use that until the sun comes out and then I make sure once the sun is out. I go outside but I keep that thing on all day and I don't know if that's good or bad. Is it good or bad?
I honestly I don't think being exposed to Bright Light in the day's going to ever be bad because really if you're outside in the day unless you know, the worst gonna happen if the temperature is very high, your body's going to say don't dehydrate and go to sleep. So you could tell actually sometimes when it's very hot, the more you get exposed.
Bright light, the Sleep where you feel in the afternoon, which is counterintuitive. So
is but that's to protect us. You think, against
dehydration. I think if you think about the human evolution from near the equator in the between noon and certain time in the afternoon, it would have been very hard for you to maintain physiological homeostatic function, being active at this very high temperature time. So I think not being was a way, that's why I think it has a major function which is still
Nothing was a way to somehow take you away from that dangerous Zone and maybe that's why people in the north. They say, in the winter we can wake up in the morning because they don't have this long light. So they sleep it more at night. But in the summer they say we feel like we can't go to sleep. We have to put all these dark curtains. So I think you know venturing that up that much known up. North has been came up with problem because if illusion was used to a certain light environment, that was completely,
Changed with a human with other animals. I think that lived there longer. They have come up with very interesting adaptation of actually measuring. Even very small changes in the light in the light intensity. Is that still occur? So, and even if you're near the the polls, even though it's always light but there is a change in the light intensity across the day-night cycle. So your system if it's linear. And remember, I told you that I pr agencies are incredibly linear, can still measure all this is lower.
Like than higher light if the organism has the ability to do that.
See, it's interesting. I've spent so much time learning from you. Fortunately about the cells and yet I never really appreciated until now, how on the one hand they are tracking the amount of light to understand when we are in time relative to the 24-hour cycle. But also that you keep mentioning this, this linear measurement of intensity that they really are trying to figure out when we are in time.
Measuring the intensity of light and of course the sun is the most intense source of light available to us. So, okay. So I think we've nailed down that first part of the day exact. Basically, it's get 10 to 30 minutes depending on how bright it is and try and do that. As as often as possible to give the system. A
regular daily is the best. This system is really about and you'll see that even for the effect on depression. It's about multiple days. It is so you don't have to worry. If you missed it one day, you know, stay longer if you want.
But if you're in a hurry and you want to do other stuff, that's a great recommendation.
So you might want to compensate with some extra time if you missed a day or two and this is why I I've heard you say before it's entirely possible to get severely jet-lagged without traveling. Absolutely. Simply by staying in being on your phone too much not getting the
sunlight. And you saw this during the pandemic lot of people mentioned that there's sleep-wake Cycles suffered a lot because if you're not going out, and if you're staying at home, and you don't
Big windows, and you're waking late, waking up late. And then you're using very bright light too late at night. Your body is going to shaft and now your day is going to start instead of like really, when the sun comes up. Let's say at six o'clock in the morning. It's gonna see your days can start at 11 o'clock in the morning. That's what your body's going to think, is the beginning of the day. So then you're not going to be able to sleep at 10 o'clock at night because now, that's really for for your body is completely different timing.
And you could see this happen during the pandemic at a very high scale. People get delayed in their sleep-wake cycle a
lot. And there is this idea of Chrono types that we all each intrinsically have a best. Rhythm of either being a morning person. You call yourself an early person or a night owl or more of a kind of standard, you know, to bed around 10:30 up around seven type thing and the and I think there are now good data, correct me if I'm wrong from the National Institutes of mental health and elsewhere.
Showing that the more we deviate from that intrinsic Rhythm, the more mental health issues and physical health issues, starts across pause.
So there is great data on this and there's a couple of things that complicate this, the first is the people who usually are late. They tell you that the society doesn't
accommodate what led by late. What do you mean people that wake up late? And go to
sleep, go to sleep late and wake up late. They they have an overwhelmingly higher level of depression and failures. I mean, clearly, I mean the reason
Reason the people say sleep early, wake up earlier better because human noticed that people who wake up good sleep early and wake up early. They do better in life. They notice that and just perform better, they prefer. But the question is is is that intrinsic to the system or is that Society because Society start things usually early or late, that's a hard question
discriminate against late rise. We in a way we
discriminate, right, but the other explanation is can write experiment the these late Riser. If
Were truly Chrono typically late, why would they shift so easily when you put them in the lab if you were really Chrono typically late and there is a phase relation between the light dark environment and your circadian clock. Then doing this camping experiment should not have caused much changes because it's not that, you know, you light is going to affect you in a certain way. Is that this is the relationship that your body decided that I'm late sleeper, late waking, so I'm honestly
Lee. I'm still on unable to figure out how much of this late waking up is controlled by the Light environment and how much is interesting. I'm sure there are differences, but are they as big as we see in the environment because you have people that go up sleep at 7 p.m. And wake up at 1 a.m. These are clearly Advanced face.
So people that go to sleep at 7 p.m. And wake up at 1 a.m. And feel good doing that.
I'm not so sure they feel good. But a lot of the time you talk to people they
They are high Achievers, but they suffer because, you know, they wake up, they go to seven PM, wake up, Advanced phase, sleep syndrome. They call it, they call it a syndrome but you know, but then you have people who would not be able to sleep till 5:00 a.m. And and not be able to wake up till 3 p.m. Right. And I'm not so sure that the Circadian system is that variable in the human population? I mean, clearly there are maybe some genetic factors that make a small percentage of like everything with a bell shape.
But I think most of the time the light environment may play a role. And once as you as we've talked about this as a long-term effect of light, once you get into a rhythm and I don't mean it as a pun in reality, once you get into a rhythm, it's hard to break out of that Rhythm because if you start sleeping late and waking up late, you're not getting the morning sun like, right? And so you're just going to be late and if you like me waking up early, you're getting the morning sunlight, you're getting what size to set.
I said his last name, wrong. The one in Stanford. Who did that
though? Yeah, Jamie's a'ight sighs. Yeah. He actually worked for side, Eisler zeitz are in size the other a lot of zz's, and eyes in those, in those names. Yeah, both phenomenal. Scientists. Yeah. What it seems to me is the case is that the only way to really know if you're meant to be an early bird as they call it an early person or a late person or somewhere in between
Is to get morning sunlight, and figure out whether or not that makes you feel better. I do understand.
Be educated about how to measure, intensity how to measure. I put it between quotation because you either get a measuring device, but you cannot depend on, I have on your eye, to measure,
intense. Okay. So, how do we do that? Because you keep coming back to this. So I guess that tells me that it's important. It's very obviously. So there are apps, like, free apps like light meter where you can walk around and hold the button down and see how many locks, you know, are in. These are
complicated because you have to point them to
Specific reason.
So how do people start to develop an intuitive sense of the measurement of intensity.
Yeah, I think, at one point I posted on Instagram, how I keep my night time at home. And I found out that my night vision is very strong. So I found that that I especially in the winter. I only need Candlelight. So, I literally used these tea lights and I put like 15 or 20 of them and romantic and it's so nice. I could see it. Clearly doesn't affect.
Circadian. See you and your cats and and my wife and it was just great. It's just great. Right, but I don't expect people to have the same night vision as me. So the simple I mean, I still people do the experiment. So if you put three or four lights in your room switch to sit for 15 minutes, you switch to off, switch to off. Let's say you're using 5 and C. After 15 minutes. You will not recognize you switch these two off. My gut feeling. Is that most people would need at least.
Least 10 times, less light than they use at night to see the problem. People use it because most of the time they didn't see the morning sunlight. They are actually hungry for light without their knowledge. So they come switch, all these lights on but at the wrong time because they
woke up late. Okay, now now I understand. So, so this morning light viewing goes Way Beyond absolute setting your clock. It's also a way to determine how much how little light you need later in the day. And we and we're going to talk about this in a moment, but
How little light you get later in the day, is a very strong determinant of things. Like when you will wake up whether or not you wake up, feeling refreshed etcetera. Let's, let's not say why? Yeah, I'm gonna
break it on your show and through that. I'm going to tell you, I think there is something else that people do need to think about which is the tripartite model that this model incorporate three components, which we talked about in details that allows us humans and all animals to incorporate the circadian clock.
Talk and its relation, to light, the homeostatic drive and the direct effect of the environment, which includes stress light, all kind of stuff. They have to be incorporated together if you think that's what I think. Right now, if you think of one alone, you will always miss something. Okay, when you think of them as a whole things really become clear. It's actually quite
amazing. Okay, we will definitely want to hear about your tripartite theory and and go into detail about this homeostatic.
I want to make sure that for people who are thinking now, I'm sure about light and how it impacts them. So, the Morning Light viewing Behavior. I like to think we've tacked down clearly, and thank you for that because there's so much information out there and I've tried to relay that information. Of course, you're my primary source for all things circadian as well as Jamie and others, of course, Walker, but I think you've made that very, very clear. Now. Let's say I've got my morning sunlight, okay.
Maybe my bright artificial light and throughout the day. You said to get a lot of light. So I'm working at my desk. Maybe I'll, I'll go out during the day a few times, but I'm working at my computer. I'm doing things. Is there anything about light viewing in the middle of the day that people should keep in mind or it? Can they just sort of freestyle it? Depending on what they're doing. Most people are not you know, in a dark room. Yeah. Throughout the
day, I Good Feeling. If you got your morning sunlight, you walk from your car slowly or you walk to work, you didn't wear.
Sunglasses. When the lights were still dim in the morning that you could freestyle it. That even if you don't get a lot of light, there is a way to just, you know, in the day you don't have to just worry about getting a lot of bright light, but personally, I like to do that. So I go out at lunch and, and have my lunch outside as well. This reminds the body that here it is even brighter now, but the evidence is that you could literally help your circadian clock by giving lights at dawn and dusk.
But again, if you think of the tripartite model, this may be important virtue. The circadian clock. But is it important for your mood? So that's where I think you need, or the homeostatic drive. So that's where you need to think about it. So for the clock for in training, your clock, you literally can in train, it only by the don't sunlight. You actually don't need
Dawn and dusk. Okay, but don't forget that. Yeah, and I appreciate that. You're distinguishing between circadian effects and other effects of light, you're being very precise, which is
Is appreciated until we hear about this tripartite model, which we will cover for, for the sake of the discussion. Let's treat the light viewing Behavior as what are the benefits or drawbacks of viewing? Light for all biological purposes. Not just circadian. Setting. So in the morning, it's clearly going to set the clock. And then during the day, if I understand correctly, the idea is to get as much bright light as you can because you're feeding it. Sounds like a sort of light hunger.
Exactly. I see I love
this way to put it. I think that is a weird light hunger considering that we are not photosynthetic organisms. There is a weird light, hungers in animals that they need to measure. They need, they need measure. And I think that relates to the season because the whole reproduction cycle of animals, going to depend on the availability of food in the environment. And if you don't know, when the seasons going to happen, they don't have calendars. It's going to be very hard to survive. So I think that's why we have
Slight hunger. That's a major hypothesis. It's not been
tested. Interesting. So then afternoon and evening start to approach. So, I've had this weird experience. Maybe you can psychologically or biologically diagnosed me now simmer. So we're if I go into a movie in the afternoon like a matinee and I come out and it's dark. I noticed a significant drop in my mood and my ability to go to sleep. Whereas if I get some view of
Of the light in the evening doesn't have to be the sunset. Although sunsets are nice, but I get some light pulse in the afternoon that I have no trouble whatsoever fall
and this happens in a daily only on a single time to
torture more or less. That's interested. Then you mentioned the camping experiment where when they went camping there, seeing the sunrise and the sunset. So what should people do in the afternoon / evening time, in terms of their light, viewing
Behavior. I mean, the best thing to do is to let
The natural light creeping Into Darkness, right? That would be the best. But clearly that would be inefficient. You wanna go home. You want to read you want to talk to your kids? You want to talk to your family. So I think you know, it's nice to extend the day. I don't think that's wrong. If you somehow can block that light from affecting your circadian
clock. So should people use blue blockers in the evening.
I personally do not like any blockers that. Take a single way.
Wavelength of light. Because again, if you think of a holistic holistic approach, yes, the blue blocker is going to prevent you from affecting your circadian, clock very much but then your vision is going to be distorted because we always see in full spectrum, the sun has this beautiful Spectrum, right? And then when you start seeing without the blue, things look yellow and it can get really weird, right? I mean, so I personally I've tried the blue blocker and I couldn't even wear them. I thought they
We're just really horrendous to be honest. Well,
along the lines of blue blockers. I think a lot of people mistakenly wear them all day long. Oh my God, that would be a lot of people do that. A lot of people do that. They think that the blue light is bad. I think that the the concept of blue light being bad, led to the a lot of product development and a lot of people are just assuming that viewing blue light is what was giving them headaches. When in fact it might have just been looking at screens at close distance. All here
is the problem, right? I mean the blue.
Ooh, life got the bad reputation because people who gave a pure blue light showed that the cause a hugely retinal damage. But again, if you're using blue light in its pure form, it has a lot of energy because the shorter wavelength but we're talking about full-spectrum light. There are ways now where you could change the spectrum of the light and keep it white between day and night and
change the content of the color
Without You noticing. So you don't even have to affect your vision. So,
Would you go about doing that?
So you just lower the level of the blue light? You don't have to eliminate it. So just dim the lights, dim the blue but keep then increase the yellow but keep all the colors in a certain white. So, you know, you could have different Warmness of white people know how to do this physicist, know how to do this. People who
work, with light, know how to do this. Well, maybe somebody in the wellness. /. I don't like the word but biohacking or Optical Community will do this. I think it's a really important.
Oh, I see so many
have a where's Lee lockers. I don't know why they love. Why I think
they're just uninformed. I think frankly. I'm
to be honest. It's easy, right? It's easier to explain to somebody if I pr agencies respond mostly to Blue remove blue. You'll be fine. Right? Right, but that's not as simple as that because they also receive Road unkown him put. So you want to actually and you know, we could go into details less boring for your listeners, but it also affect the adaptation properties of the whole retina. So you don't want to do something. So drastic, that you
Just one color of the spectrum. It just seems very counterintuitive to me to be honest.
You've told me before, as well, that just because these intrinsically photosensitive circadian, setting, ganglion cells respond, best to Blue Light if the light is bright enough because they also get input from other components of the eye. It doesn't matter if you block the blues. Yeah, if you're looking at bright light at night, you're going to disrupt your circadian outside.
And that's why I didn't want to go into.
Ooh, the boring details, but themself the photoreceptors have a wide range of responsiveness. So they are most sensitive to blue light. But that doesn't mean they don't respond to green light or two shorter. Them, who like they respond to very, very wide spectrum with different sensitivities. So, unless you understand the system just removing 480. I don't think is going to
do a hundred am. Yeah, so your home is a cave at night basically with some with some kitten.
Escaped with candles. That's what I write and you and your I did I when you're in your chats and your lovely wife, yeah, I know who's also a phenomenal scientist in their own, right. She is and but you do keep your home quite dim to dark at night.
In fact, I did go to two meetings with some of my friends who work on this and they really struggled with me. They said we could have broken our legs living in the same light environment that you do. So I am an extreme, but I measured it for
Myself and I asked raise you my wife if she's okay with it. She also liked the dimness. Both of us can see well in Indian conditions and and that helps us a lot. But I think you have to measure it for yourself. You really have to do. It's a very simple experiment. Just try to dim the light as much as you can. I call it the minimum amount of light you require to see comfortably
and that's how you want your environment. Ideally at night.
This is what I think is the game changer.
If you reach to a level where it's just barely, you're literally on the cusp of seeing uncomfortably versus seeing very comfortably. You are going to be very much better than I don't like to make it completely dark. I think complete darkness, induce anxiety in humans, to be honest. So, I don't like complete darkness inside.
It'll, don't like complete darkness. They like like, animal. Even nocturnal animals. Don't
like complete darkness. I mean, we have studies in animals.
Ones that are nocturnal that. If you put them in complete darkness for several weeks, they could they have severe anxiety and depression like effect. So keep the light them, you know, use red light that is very dim. If you want to keep the room for sleeping red light that is very dim, has very small effect on on on circadian, clock and below 10, lakhs of red light literally doesn't affect sleep at all. So there are ways to do it. It just we need
Educate the public and I feel like you literally need your whole lecture to just explain to the people how to deal with life, because it's not as simple as people
think. Well, that's what we're doing here. We're stepping through a piece by piece and and the reason we're doing that is because it's not as simple as saying just block blue light, or get a lot of light during the day. And I mean, minimal just
had money in perspective to tell it. We only have three different cones in our retina that respond to three different colors.
We call them red cones for Simplicity, green cones and blue cones. Yet. We have only three of these, but we could see massive palette of colors. So, that tells you something, if the system was just simply about a single color and it's just removing 480, or just blew is sufficient. Then we should only see in red, yellow and blue. We shouldn't see all these different Hues of color, but because the system is not that we see all these different colors and that
That's why it's important to remind people. That the white light is made of many different colors. It's actually like the rainbow. That's why you see the rainbow. It's made of many colors. White light is never, truly white. It's made of lot of different
colors. It's like the Pink Floyd album cover. Exactly. Come exactly, exactly. So dim at night, maybe dim red, light, ideally, or candle light, find that minimum required light level this season. Just
make sure when you lower the lights it for,
Or at least 10 to 15 minutes. Let your system adopt because if you had it bright light and you switch it off. Surely, you're gonna suffer because your system didn't adapt it. It was used to very bright light. So you want to engage your rods, which take a long time to dark adapt. So that's why I tell you just wait a little bit. Don't just switch it off there. I don't see, put it on, put it off, sit down wait for 10 minutes, ideally 15 minutes and then see how you see. And then once you do that,
You will notice that actually I could see quite well, even with much less
light.
What do you do regarding
screens? Yeah, that's that's the hardest thing. Again. I mean, there are beautiful programs that change the whole intensity and color of the screen. These could help them your screen at night to the lowest part. I mean, yes, you won't see it when you wake up in the morning, but then you can increase the intensity. So, try to decrease. I mean, just what we were talking about think of light intensity, duration, color, and time of day, you really have to keep these four things together.
Right,
we've room together at a couple meetings from time to time no longer because one of us not to be named has a severe snoring issue that the other one a pseudo homicidal can guess who that was, but I've seen you check your phone after dark once or twice and you did it by sort of putting your phone away from you, right? And and actually I'm sort of half.
King but I and you Dim it quite a bit. I'm sorry. Half joking. But it actually makes sense that, you know, if you shine a flashlight in your eye, it's much brighter than it might be
going direct line. So if you just look in the side, most of the light is going to go this way and you're only things
so you, okay? So and as silly as, that might seem to people listening, I mean, what it means is that getting bright light in your eyes at night, is something that you really want to avoid, and but there is the reality that and even when I
check sometimes, if you know, if I have something and I
It's so fast and switch it off, so fast, so
I'm also aware of my messages.
I'm also aware of the duration, right? So duration, intensity color, and time of day. Ideally, I should not check iPhones and iPads. I don't use iPad at night because it's hard to lower it enough because it's a huge. But even my iPhone, I try not to use it at night and like once it becomes 8:30 or 9:00. I don't look at it at all. Unless
it's World Cup or Euro Cup, in which centers on 24,
Towers everybody that's on the every four years. It's a big soccer fan. All right. This has been incredibly no pun, Illuminating. Let's talk about the relationship between light and some of these other non circadian or pseudo circadian effects, and we will try and Link those but you had a what I consider absolutely Landmark. Beautiful paper published in nature a few years ago, showing
That if you disrupt the exposure to light or the timing of the exposure to light that their dramatic effects on the stress system and on the learning and memory system, we could talk about each of those separately or together, what, what are the effects on stress? And the effects on learning when light viewing behavior and sleep-wake Cycles are disrupted. Yeah.
So just to remind you, you know.
Oh that. But to remind your listeners that I was trained as a circadian biologists, so I really was indoctrinated into thinking that light has to affect the clock, which then caused all these different effects. So that's that's what I believe. That's my Dogma. That's what would have made me really happy and then Tara legates and Cara altemus joined the lab and said, and we started discussing a lot of data. And we said, what if there is a direct effect of light that we're missing independent of the circadian clock.
This is not an easy question to ask to answer because as we've been talking all along light affects the circadian clock. So how could you give light at different times of the day and not mess up the circadian clock? Luckily? We came up with such a way and that's why it was important to do this experiment the way we did them and we proved that this light dark cycle. Does not disrupt the clock. There is still a circadian rhythm and does not close sleep, does not go sleep deprivation, and yet
Surprisingly, if you give light at the wrong time of the day, even without disrupting the circadian clock or without causing sleep, deprivation, as you mentioned, you get a huge mood changes in the organisms and you get learning deficit. So, this really and at the time, people have really hit us hard. I mean, it was really hard to publish this work and, and you could,
yeah. Well, it came out in nature. So I in the end you prevailed, but I
To make sure that I understand. So you're, you're saying that. Yes, there are effects of light on the Circadian rhythm obsolete. Meaning, sleep and wakefulness. Yes, and their timing. However, there are Direct effects of light on mood that can be dissociated from the effects on on sleep and waking. So, if I interpret that correctly, that could mean that when we view light and how much light could make us feel happier or less happy or even depressed stressed.
Is learning, Etc.
Bingo, and even if we're sleeping, and waking up at the appropriate time, bingo, I mean, eventually, because we're
talking about the whole system. Eventually when you start having the other problems, you also develop sleep problems, but you're absolutely right. And in fact, now research from Diego, Fernandez, in the library have found that. Now we know that they actually require different brain regions. So we don't only have a theory. We don't only have a light environment that showed they can be dissociated.
You know, that they use completely different brain regions. So the scn that I told you about earlier, the place where the central pacemaker is, the one that received direct input from the retina through the IP addresses, to adjust. Your circadian. Clock is not the area that receives the light input for mood regulation. It's a completely different brain regions. What's the brain region called? So the brain region we called it the Perry have been Allure nucleus. I'm not so sure how good or bad the name but doesn't matter is that PHP. And what's really amazing.
This region also receives direct input from the IP addresses, but projects to areas in the brain that are known to regulate mood including the ventromedial prefrontal. Prefrontal cortex, which has been studied for many years to be impacted in a human depression. So just by this, amazing Serendipity, to find that a region that is so deep in the Advanced Brain like the the prefrontal cortex is your executive brain one.
The most elaborated in humans to see that they receive input from these ancient photoreceptor was stunning to us. And told us how much we didn't understand the importance of light on human behavior. So how does
that finding inform daily protocols for you? Or for other people? I realize you can't leap to always from one paper to daily protocol, but if light indeed does control, prefrontal cortex executive function learning.
Stress and mood and let's say I'm waking up. That's where I'm gonna be sleeping. That's what should I do differently.
That's why we came up with the tripartite model because yes, we could think about just adjusting the clock with lights in and being dark throughout the day, but that may not be important for your whole physiological function. So now if we include these other effects of line, that's why I prefer to still get a lot of light in the day. I don't want to be in very dim light condition throughout the day. I see. So even though it doesn't
Faked your clock as you beautifully said, Andrew, it may affect your mood and learning and memory, it may affect your alertness level which can allow you to learn better. It may affect your homeostatic drive. Maybe your home is static Factory will go higher, so you could sleep earlier. So it's important to think of light as stimulating. All these brain regions, which means is producing more activity, which in reality. This is how people think of the homeostatic drive that the more active, you are, the more the homeostatic Drive is built up.
Up the better, you sleep. So that's why we came up with the tripartite model because as a circadian biologists, I only thought of light through the circadian clock affecting Behavior. As a sleep biologists. They only thought of the homeostatic Drive affecting sleep affecting behavior, and for people who study light for vision and other funds, they thought only of the environmental input. But now if you put them all together, you get with this tripartite model where it's really mind-boggling and it makes so much sense. The organism
Want to depend on a single component, but if you could incorporate these three together, you could have a beautiful system that is well adapted. So let me tell you the sleep-wake cycle, right? So we know, there is a homeostatic drive to affect sleep, without beautiful talks about that, which is basically the
longer you're awake, the more you
want to be as so that's your homeostatic Drive. We've talked about the Circadian influence of sleep and the fact that light dark cycle affect the Circadian system, which eventually affect sleep. So these two components are
Around soon. Now, the third factor is your direct light or environmental input. How much stress, how much light you get from. There? Also can be highly impact sleep. So even if you have a good circadian and homeostatic drive, if you're getting red light at the wrong time of the day, or if you're being stressed and thinking at the, then your sleep is gonna suffer. So you have to think of the three together to have a beautiful sleep-wake cycle and that's why we came up with the tripartite motor, the same thing happens.
Feeding, I could beautifully, put it to people your hunger. Your energy level is measured by the arcuate. Nucleus your daily intake of food is again dependent on the sea. And on light dark input. We found that if food is not available. There is yet a third input that is not depend on the scn, not depend on the arcuate depending on a completely brain different brain regions. So the animal can actually start looking or the human can start looking for food when it's scarce, even at
A time when they are not supposed to be active. So that's how the organism think they have to evaluate multiple inputs for them to decide. What is the best physiological outcome at that? Moment at that season? I
say so I want to get into arcuate and feeding but just to keep make sure we can keep our hands around this tripartite model. So if I understand correctly, we've got the Circadian influence. Then you've also got the drive to sleep. Actually. One of the ways that I think that can be best, understood is
If somebody ever pulls an all-nighter, they get tired around 11 or 12 or so, and then very tired around 3:00, 4:00 a.m. But then even if you stay up some time right around 7:00 or 8:00 a.m. Your normal, wake up time, you start to feel alert again, exactly. That's because the Sleep Drive is extremely strong, but there's a circadian rhythm that drives wakefulness and exact. Okay. So those two of the components, right before we get into the feeding component. I want to talk about these Direct effects of light on move. Okay, Diego Fernando
Data,
and this Perry Hub, any others that sure. So, let's just for the moment set aside, the try part of the tripartite model and just focus on, what are the Direct effects of light on mood. And the way that I interpret, what you said so far, is that the protocol that emerges from this? If one is trying to optimize their mood is yes. See, light view light, I should say early in the day, in order to set your circadian clock, maybe also in the evening as well. And of course, avoid light at night. Get it as
Jim as possible. However, you said it's also a good idea to get as much bright light during the day as you safely can, in order to improve your mood independently of regulating your sleep-wake cycle. And
that's a hypothesis. Here's the problem where it's not going to be as satisfying as the Circadian is that as you know, this brain region has been discovered. Very recently habenula, the ferry have been you know,
what, we've known about it a long time, but nobody knew what it
did. So when you about that vanilla, but that's why the name is.
If using its action did not have any lights off, it's the period or near the Hub, and it's near the honey. Why don't you just call it the summer hot or nuclei should have, I don't know why I do that, maybe because if you do
that, it's not. Okay. Okay. So for here, ever, after the Perry have been your learn nucleus, we should probably called the hot our Wikipedia line it up. Okay, so this structure is taking light.
Right? An independent of sleep rhythms and circadian rhythms. It's driving changes, anything food. How does it do that? Is through the dopamine system, the Sir Henry V.
We still recently, we haven't identified this Vision very well. We don't know what light does to it. We don't know how it interacts. So this is an area that is right, for discoveries. And we're working on this right now, but that's why I said, it's not satisfying. This is like the function of sleep. Why do we sleep? We know sleep is very important to us, but we still don't have it. Satisfying.
Why do we sleep, right? See, we have a wide questions. The, why questions, I think
it's our good friend and colleague at University of Washington. Trust van gelder, who always says, when somebody asks, why the best answer is just to say, I wasn't consulted at the design. Phase. Exactly. Right? None of us really know
not, but the point is, maybe I shouldn't have said, why? What is the function of sleep? It's still very hard to know. Why would what is the reason organisms have to go offline for so long?
You know, people assume it's for repair assume it's for learning and memory assume all kind of stuff. But there is really no clear function for sleeping. There is no clear function for sleeping. I mean, if you talk to people, there are hypotheses.
I mean, all we know is that if you don't sleep with yourself is very fractured, you get
messed up and you could die even, right? I mean, it's really bad if you don't sleep, but we don't know. What is the function. What is the, what is that sleep have gone to?
Isms that couldn't have done with rest. What if you just could rest, without sleeping, just sit down and
rest. Well, my lab is trying to figure out whether or not these non sleep, deep rest. Protocols can compensate for for sleep. In that women, obviously sleep is better, but many people are not going to getting the sleep that they need. But right. But, okay, so and if people are sensing that's Amber and I are about to start talking over each other and arguing that's always the goal when we talk, right? Unlike other scientists, I interact with when sammer and I get together, it's considered.
Successful conversation if we get into a big fight and then go for a big meal where I pick the restaurant. Okay. So let's talk about food and eating an appetite. You had yet another
Yes, I greatly admire your success in this way. Yet another, incredible Discovery showing that there are directs of direct, excuse me, effects of light, on appetite and feeding Behavior to maybe you could just summarize those results. And for
honestly, that paper is the one that allowed us to come with the tripartite model because we were thinking completely wrong about it. We wanted this experiment it. It'd be fun for your audience to hear. Why? We started this experiment.
Bird that when we discover the IPR GCS, we figured if they are the only really to entrain the circadian clock, then you could kill them and have an animal opposite to the one that we spoke tour. Human opposite to the one that we spoke about earlier where instead of having no pattern vision and have circadian photo entrainment. We could produce an animal that have patterned Vision but no circadian photo in
train. So circadian. Blind
circadian blind, but pattern cited and we see
Exceeded in that, the problem when you have these animals, which I have told you many times already is that they don't adjust to the day-night cycle. So doing experiments on them, become
very complicated. What is their behavior? Like if you don't have these cells, are they awake and asleep? They wait they
just drift like the humans. We've talked
about. They think they're in Las Vegas. They know clock. It was exactly stay up later every night
and they come either defend their clock. If it's a clock is shorter. They come in earlier if their clock is longer, they come in. So they really messed up.
They really don't adjust to the, if they were in the wild, they'll be eliminated in a second, right? There is no way they survived. So, me and Diego started talking and were like, what if we use none light in training agent and what is the strong young man, light in training Asian food? So we thought that the light defective animals will have more sensitivity to food and Trend because as you know more than me, this is an area that you've worked really well on for vision. If your image blind you
Or hearing and somatosensory get improved right? The, the lack of vision improves your hearing and sensation, but we found actually that if you don't have the light to system, actually you're feeding a bit the food ability to entrain, the animal goes completely to the ground completely opposite to what we predicted. So light
viewing and feeding Behavior are interacting in ways that support one another. And that's
why we came with the tripartite model with
Bigger is different than sensation of the environment when you sense with vision vision and hearing interact, but your vision is a real full modality. You want to see, that's what Vision want to do. You want to hear? That's what hearing want to do. You want to sense? That's what sensing want to do, but for the Circadian System, Light food, all these in training Asian, they somehow have to interact to keep it coherent system. You don't just assume if you remove light, this one is going to be
Unger know. They need to know each other's the light informs when the animals gonna eat.
Well, what I like about this so much is that, you know, in the other in the world outside of Science in which I don't really exist in, but that I see a lot of this kind of Wellness, you know, stuff like this, all this mind/body integration stuff. It's interesting because people view the body more. As a system, write a system of organs that interact as opposed to the way that standard
Fines and medical profession is like you work on the liver, or your ear, nose and throat or Heart and Lung or brain or that's a great way of thinking, you know, but the biology is integrated. Yeah, I mean and so for somebody who's interested in affecting their eating Behavior, something that you are familiar with and that we will talk more about your experiences of in a moment.
How should they use light in order to adjust their eating Behavior?
Right? So now that I've told you about all these interaction between the different inputs to the circadian clock, just you think about it as an engineer. What would be the best thing? The best thing is to know, when your food times happen in the day? When should you get light? And where is your circuit? When is your circadian clock in your system? Right? So, if you eat at very specific times of the day, that's a
Another signal that is telling your body, your clock, you're in a certain time of the day. So if you're having lunch at the correct time every day and you're getting bright light, now you have two systems that are informing, you o'clock. Your clock is going to be better. So, regular mealtimes regularly mean tabs, that fit your circadian clock. So, and in fact, if you do that, when when I started doing this, and it helped me lose weight, is that I'm exposing myself to the right amount of Light Dark cycle. I'm eating at regular time.
It is amazing. You would be not hungry. Let's say, let's say, you eat at noon. You will not feel any hunger at 11:45 and then all of a sudden, the hunger jumpsuit, this is clearly not an energy issue because it could not be that
drastic right. Now. The desire to eat, is mainly driven by these these cues, these hormone cues that are very exquisitely, timed to exhaust sleep-wake cycle, but also
to light exact and you know in the wild you could imagine why.
Level through the accurate is the arcuate nucleus
can explain to people what the arcuate is because I don't think we've done that adequately. The arcuate nucleus is an area of the hypothalamus that drives hunger and feeding behavior. And what we're talking about is the fact that it's taking cues from your viewing of light, believe it or not, is impacting your level of hunger. And this is a non-trivial way in which your timing of hunger and amount of hunger is regulated by when and how much light you
Of you, so let me ask you a couple practice. And I just,
this is really a before you ask me a story. Andrew. We should we going to fight? But to me is the the interesting thing to think about it in the wild when you didn't have the availability of food that we have, the arcuate plays a huge important role because if you're not, if you weren't successful in getting food, then the arc is going to tell you look, you have to take risk and go get food because your energy level is very low and that's great. That's tons of great research about that.
But I think what's missing is the fact in a human's we're not getting to a situation. Most of us. We're not getting to a situation where we have no energy levels most of the time actually we eat not because we want to because we are really have no energy but because we want to eat. So I think that's why I feel that the timing is very important for us because we always have enough energy level for us to eat.
Well, I mean I enjoy eating so much that I'll eat just for the sensation of chewing through. I mean
I enjoy the taste too and I enjoy the social aspects from those are part of it. But I literally enjoy the physical apps chewing. Absolutely. Uh-huh, which explains a lot. Okay.
So how
regular are you or do you recommend people be about mealtimes? Because what I'm hearing is that light viewing behavior is pretty straightforward, get a lot of light in the morning and throughout the day, minimize it in the evening. And at night.
Really speaking for sake of mood and circadian rhythm, but for sake of regulating timing and quality, I should also say a food intake because people clearly make better choices about food intake when they are anticipating a meal and they aren't constantly hungry. And so, the ability to regulate hunger for particular, phases of the Circadian cycle is quite valuable for all people. Not just people trying to lose weight, but all people
Are we talking about down to the minute? Like if I knew all right, Plus or so, 12 noon is my normal lunch. Let's say, plus or minus half an hour. Okay, so e around between 11:30 and 12:00 30,
if that's the time, and it depends, if you also, do multiple meals, remember three meals, that's decision that somebody came up with, I don't know why
nowadays people are fewer. People are doing that. I yeah. Giving our friend such a cheap and has worked,
right? I mean, so you could have two meals, you could have
Very multiple meals that are distributed across your active time. I agree with Sachin span this work that try to avoid eating when your system is supposed to be relaxing when you're supposed to be at non-active time. So, you know, limit your eating to the active time of your of your cycle and that seemed to be and Joe takashi's doing some beautiful stuff on this. That seems to be incredibly important for
The Circadian and for health and for our yeah, I mean such in a were referring to such in pandas work. He wrote a beautiful book called the Circadian and code maybe Samer with with some luck. You'll write a book as well. Meaning the world would be lucky to have that book but such ins data really strongly points, to the fact that Liver Health brain health, metabolic factors and endocrine factors in various systems and organs. All seem to benefit from having a period of each 24-hour.
Day in which we are not eating anything, and then eating at very regular sometimes.
Let's talk about eating and meal times. And let's move a little bit away from the science for the moment. Although we will return to it and talk a little bit more about your experience with eating and mealtimes. So you're looking in good shape lately. Thank you. I know you've been putting work into it. Yeah, we talked a lot and you've been exercising and you've been eating. Well, meaning quality food. You just came back from Jordan, where I'm assuming the food is amazing.
It's the food is amazing. And honestly usual.
I gained a lot of weight in Jordan, but this time, I didn't gain any weight, which was really
nice. So yeah, you've when I met you, you were probably about a hundred pounds heavier than you are now
275 pounds of 219. That's crazy. Yeah,
you had a lot of vigor than and you have a lot of vigor now, but I know that you undertook a very specific protocol in order to lose the weight based on your understanding of the Circadian system.
Stillman of light and appetite and mood. Maybe you could just tell us a little bit about what that schedule looks like. And we realize that this is not a prescriptive for everybody. But you found what worked for you. Maybe just describe those.
I mean, honestly, I followed my circadian cycle, right? I've, we were what we've talked about, right? So I dim the light at night, I slept at regular hours. I ate my major food in breakfast and lunch, when I'm really active and I'm really hungry and at night when I avoid dinner because
Because my circadian system really shuts off at 3:00. I'm an early person. Like you could give me anything. I would eat before, three after three. Nothing appeals to me anymore. My system is shut off.
What time are you going to sleep? And what time are you waiting? So
and my case is, I should have put this I mean I go to sleep literally at 9:00 a.m. 9:00 p.m. I mean, I literally five minutes after 9 p.m. I'm completely out and I wake up between 4:30 and 5:00 a.m. So if I extend that I coach 6 a.m. But very rarely depends of how tired I was.
Was and that, as I recall, was an important set of changes for you to be able to regulate your food into,
absolutely. Because then I'm having very big breakfast at, and again, for different peoples. Different. I have a big breakfast at 7:00 a.m. Maximum. So I have a big breakfast coffee and all the stuff then I have some simple snack around 10. Then I have regularly lunch at noon or between noon to 1, then I have another snack at 3 and the hardest time to
The food is between 12 and 3. This is what I'm I really feel hungry or is your
equivalent of kind of lay evening for most? Yeah. So for me, it would probably between seven and 10 PX. Exactly
exactly. And then at nighttime, I'm completely not hungry but usually as you said the beauty or the the enjoyment of food, like when my wife kicks, cook some really beautiful Indian food, I eat but I'm not hungry and I notice if I eat with that, I usually gain weight, but if I regulate that at night, I also lose weight. So there is a combination
Turn off all these things that help you adjust these. This the the input of food, the input of light, the input of the clock and the drive to Hung.
Yeah. I appreciate you sharing that we and I want to emphasize that some people are not hungry early in the day. They might be late shifted people, in which case eating later in the day. We'll work well to
work as long as they don't eat early in the morning. That's just you have to work with your schedule with your active schedule. Yeah, you know, I've been talking about this
offline for years. I'm glad we're finally having this discussion public.
Ali now, but we're talking about really is finding your ideal sleep schedule. Exactly. Exactly. Finding your ideal eating schedule. Exactly. And understanding how those two things interact.
And, you know, the nice thing, as you said to finding them out, is going to help you to understand how they interact because we know from the tripartite model that they are all interconnected and for each person they going to be interconnected differently. So for each person you would you know, for me, if I exercise at night, I'm going to miss.
My whole system below. When do you exercise morning morning works? Great for me. I mean, it's amazing morning exercise. For me works great if I tried one time because it was easier for me to exercise at night, before I leave when the traffic is there from that? I shall. I think that messed me up because I couldn't sleep well, and I couldn't wake up. Well, and that led to more changes in my food. I gained weight again. Actually, believe it or not, even though I was exercising. So I think this really makes me think that
You have to think of the tripartite model to see where is the best times and what is the best interrelation between the different component? As you beautifully said between your meal times, your light exposure and your sleep that works for you?
Well, thank you that usually Summers insulting me today. He's complimenting me. I'm going to compliment him right back by saying this is the first time that I've ever really understood. How yes, light can control sleep. Yes, it can, in control.
Yes, it can impact feeding, but that it's really about doing the self-exploration to align those in the way that works best in what I'm hearing. Tell me if I'm wrong. But what I'm hearing is that once you understand what gives you the best sleep-wake cycle, then you should exercise during the period of time in which you feel most alert. And if it works for your schedule. Ideally, you would also eat during the time in which you feel most alert and then stop eating.
And stoplight viewing Behavior as you head towards sleep.
So, the only thing I would say that complicates all of this and that's what makes me sad is your light
exposure mine, personally. Sorry. Just yeah,
that the people's light exposure, right? This is what complicates it because you're not going to be able to figure all this out. If you're shifting yourself out of your comfort zone by viewing by viewing light at the wrong time of the day. So let's say, let's say, you're if you were under an idol natural,
Dishes, you're a person who would sleep later than me. Let's say We'll sleep at midnight and wake up at 8 a.m. Let's say you don't eat anything till noon. And as you said, you eat late in the evening, then this would be perfect for you. But now see what happens if you now you include the light component. Now, if you push your sleeve from Midnight to 4:00 a.m. Now, you're waking up in the morning and use your action is really not the morning, you're working. I'm sorry at noon, instead of eight o'clock and the time.
Are you not supposed to be hungry now? You're going to start eating directly at noon or something like that or even delay it and now you're shifting your whole cycle. And you don't know if this interaction between your sleeve feeding and the light dark environment. I'll still gonna be maintained or not. And that's the problem that people have somos, you
know, as I'm hearing, that's what I'm realizing is. Most of us, probably me, included are messing up at least one, two or three of these components Zack, but that the, that the probe the way too,
Figure out what's right for oneself is to start manipulating light exposure.
I'm I'm going to be honest. I'm biased because I believe that light is the stronger, the strongest timegiver and we a lot of people disagree. Some people
think feeding is, I always thought that light was the primaries. I gave her the primary.
Yeah, but a lot of people think it's food. A lot of people. Even sometimes mention social interaction, a read the literature. I agree with you. I
totally agree. I mean my understanding is that light is the most powerful driver of the
I swear,
that's what I think we need to regulate this first and everything else fits. And, you know, the nice thing is that your sleep-wake cycle and exercise, tell, you really bluntly if you're doing it, right?
Or not. Tell me more about that. I tell you more,
when I shifted my exercise, honestly things fell apart, like, never. Before, when you moved from
exercising early in the morning. Yeah, it completely
fell apart for me. I didn't enjoy exercise at night. My pain, tolerance for exercise wasn't as good. I'm talking with n equals 1.
I'm aware of this. I've never tested this empirically but at least to me it really messed up. Everything. I started having problems because my body temperature will go up and that will affect my sleep. I possibly was running in the gym with a lot of lights. So maybe the light was a component but for me, exercising in the morning, it's so much better for me. But a lot of people can't even think of exercising in the morning. So it depends on when you feel comfortable in your sleep-wake cycle and your exercise. I think that tells you if you're
Stem is in in synchrony with one
another that's really interesting. You know, I we're good friends, our friend, Pat dossett, right. That we both know, you know, nine years in the SEAL Teams and he's one of these people says, you know, he's happy to go for a run or Swim anytime between 4:30 a.m. And 6 a.m. And he'll train in the afternoon too. Because you know, he's Seal Team guy and they'll do whatever anytime that's part of the phenotype, but he feels best doing that, right? I'm a mid. I like to exercise mid-morning and I'm Happy to Skip eating.
Until 12:00 or 1:00. And I like to go to sleep around 11:30 12:00 because I'm a normal human being rather than you who goes to bed at night about. Yeah,
actually, I've never asked him
what tap. So, Pat's ideal to sleep time. I've asked him this would be around 8:30 or 9:00 except now, no, but he has yes, but he has two young children, two years old, and a newborn. And so, the cyclist disrupted area that's
known, right. I mean, that the effect of childbearing and I think they're, we could talk about this.
That's more complicated. But that's pretty pretty much.
Yeah. Yeah. I mean, I think we need to come up with a new name for chronotype because chronic type implies that it's just about sleep and wake being an early bird or a night owl. And what we're also talking about is how exercise and eating match on to those
and the phase relation.
Right. And the phases between different components as you said, because they interact because they interact, right? And they don't have to be in the same phase. Like, let's say, my light and food could be very close to each other. As you like that food could be different. Right? The phases don't have to be. They can be plastic. So you have to find this for yourself. You may, you may be a person who eats late at night exercises late at night or you may be a personal exercise, early eat later. So it doesn't as long as the phase is is good. That's what
That's what you have to find
out. Okay, and if I understand correctly, when you're talking about phase relationship, it means you want to lump exercise, feeding and light for, on sleep and sleep. In a way that as a coherent and total system makes you feel really good. Tim poorly integrate
order. Uh-huh. Absolutely. Yeah, that's and I think that and I could tell you to me is literally getting exposed to some, you know, clearly in the morning. Clearly at noon, I go out. I keep my windows in the
office completely open eating mostly in the early time of the day and exercising and literally at the end part of the day. I'm not really in a more thoughtful vegetative state. Like I really can't like after five. I tell my students. If you want to tell me anything complicated, you're wasting your time. My brain just doesn't function. So even though I only sleep at night, but I'm really starting to shut off ramp down. Really. I mean, it's, you know, I could send the email talk about brainless.
Stuff, but my power my energy to do powerful stuff. Really dropped tremendously. So all my students who know me very well. They put the meetings with me early in the morning because they know this is when I'm so everything for me. And for me, it's very tight. So it could be different from its very close to the in the morning is all tied together and literally the remaining part seems to be just, you know, vegetative
state. Yeah. You and my Bulldog Costello who unfortunately passed away.
They recently had that, and yeah, I did not. That's a marine. Costello were good friends. Yes. Sorry to break it to you with here. Yeah, he had a good long life and he went easy, but he had a circadian clock to basically, just sleep around 24 hours a day, minimal activity, interspersed every third day or so. You do have this morning Vigor. Yes, and that's that. I think other people are going to have more of an afternoon Vigor. Do you think that this can change across the lifespan? It's, the rumor. Is that teenagers?
Yours naturally want to sleep in later and stay up later. Do you think that social Rhythm or do you think that that's actually biologically?
Yeah, that's a tough question. I mean, it could be both one thing that worries me is that it seems that if anything with age this morning with rigor get stronger,
so you want people become more of morning more and more. Why is that? Were you? I think that's good
because for me, I'm already very shifted morning. I don't want to be one of these 7 p.m. To 1 a.m. Sleepers at
some
Point on the other hand. It's also kind of nice because it's quiet and you can get work done. But
honestly from 4:30 to 7:30, when my wife wake up. Its it can be very lonely. Yes, you achieve a lot but it's quiet outside. It's, you know, so it I don't want to be at 1 a.m. Let's put it this way. I
don't you tell Samurai is more social than I am. That's right on.
That is true. So
you should touch on that actually. So, so your wife is, she follows a different schedule. Yeah, and, and so, social rhythm is important.
Certainly, I think, what should we do? How should we conceptualize? And how should we adjust ourselves according to the social?
Honestly, love this this, this hypothesis that people came up with and Pat's kids reminded me off because kids are really gonna disrupt your sleep week cycle. It seems like there is a Chrono attraction that usually people who attract each others, have actually different sleep-wake schedule and the idea being is that this allows them to take care of their kids.
Throughout the day night cycle
and have a peaceful marriage and have a peaceful
marriage. Anyway, right so I mean we didn't have kids me and rages. So maybe this is but it seems like evolutionary. It makes sense that if you want to protect your, protect your kids, you don't want everybody to be morning rigor and then the kids don't have. So you want the distributed across. I
think it's a reasonable argument. I've heard that one of the reasons that people think that the clock is not exactly 24 hours, but it's 24 hours.
Plus or minus, you know, 20 minutes or so is because we believe that we evolved in Clans or groups Villages. Whatever that we're about a hundred to two hundred people. And in order to have protection around the early morning hours when we're vulnerable to predation, and in the late night hours, that you would want some individuals of our species to be naturally, more like night owls and some more like early people. So your theory of parenting is is similar in that way.
Way, right, the social rhythm is is a powerful Rhythm though. Meaning, if I go out and I'm tired. Let's say I'm tired of like 9:30. I don't want to go out.
Like, I'm going to need is say something about that. I think the social rhythm is powerful at the obviously levels. Like, it affects your sleep. It affects how much you wake up, or eat, but I'm not. So sure is as powerful as people think on the clock. Now eventually, it will mess up the clock because now, if you're doing a lot of social at night, getting enough light,
Eating at the wrong time of the day. Eventually you're going to have an effect but I don't think that's the social interactions themselves have been shown to affect your clock. Very
strongly for some reason. That's good to know. Well, for people hearing this, they're probably getting the impression like, I'm the night owl and then Samer is the one that's in bed at nine and then, you know, wakes up at 4:00, but having attended many meetings with Samurai can tell you that he's the party animal. So let's talk about that.
I mean, let's talk about the fact that you're the partier, who's up until two dancing at these. At these various meetings, which I've seen, Yeah, we actually a good dancer. I'm told, but
What should we do when we do stay up. Very late for whatever reason could be, because we had to take a midnight trip to the hospital, unfortunate reason, or it could be because you're in the presence of people that you don't see very often and you and you go out for a really nice night out on the town and you and you get to sleep around 2:30 or 3:00 in the morning. How should one get back on schedule. Do you force yourself to then, get up and view light at the normal time that you would get up in view? Light, or do you allow yourself to sleep in? What? What's the optimal power?
Allow myself sleeping. And remember. This is a long-term effect. This is something that you live with for a long period and and remember I told you about the experiments we did with the Moody's required, two weeks of that light schedule to cause mood disturbances. So these don't happen just in a single day. So this is the way you
justify staying out late every
once in a while. Well, in that in the meetings, you've seen me and I've done this for five or six days continuously, but what you didn't see that, when I came back to my home, it took me two weeks as if I did a jet lag. So I really
You suffer for two weeks after doing a six crazy night of staying up at night drinking at the wrong time of the day. So it's not that I'm completely okay with it. When I go back, everything goes back. It takes me actually literally two weeks to recover from the Circadian. Rhythm meeting that you've seen me partying
at some point, which is kind of ironic. That's okay. I know Rhythm, meaning people are totally disrupting the Circadian cycle, but scientists are human beings too, right?
So I think if you do it,
At very little occasions, I think you should not worry too much that this will have a lasting impact and the good news is that if you re adjust your schedule, you could come back to it. The problem is, when you maintain these wrong schedule for prolonged team and becomes, chronic prolonged periods of time. That's when you have the problems and the accumulation of the problems. So when you have sleeping problem, you produce metabolite problem. When you have metallic problems, you produce lack of exercise and you could see how things can
Spider-Man out very quickly and then it would be hard to come back to
it. Well, certainly sleep disruption is both a symptom of end. Yes. A cause of almost all absolute mental health disorders, right? And certainly the metabolic syndromes that people are talking about nowadays and all of this, it all funnels back to light
this event. So remarkable.
Yes, and so we have these devices and I'm, I use my phone and I use my computer, but do you think
That the mere dimming of the screen or not interacting with screens after you know, with it's a 90 minutes or two hours before bedtime according to what we're saying today.
This should have a profound effect on it, does
all these fun. I really believe it does and I you know, again, I think as Pat has did this this this inventions where you get a pouch where you put your phone in a pouch.
Okay. So what but summer is referring to is our friend, Pat, this former SEAL team member that we that was also very impressive person in the landscape of business and family Etc. Real, a superhuman from a by any regard has this habit of taking his
Phone and putting it into a sealed pouch evening. So it's basically an in his world and he
sends you actually these the seal, you know, batches and so that I think is a great idea because not only it will take away the light from you. But it also take away the distraction because you wanna repair and recover and sleep does that and if you have your phone dinging all the time or or the light flashing from it is you're just not getting enough sleep and you're causing yourself major.
Seems
I never asked you this but I realize now that I should have long ago, but I'll ask you now. Why and how did you get into all the
stuff? Yeah, I mean, honestly, I first of all I wanted to become a you know, I wanted to study genetics and I knew I wanted to do PhD in genetics, but I only got accepted in one University at the time and I joined the learning and memory lab and I like learning and memory at the
Worked in the snails and that Leisure California can and started looking at learning and memory but then the same lab was looking at these daily variation. I was really struck like you never think about it outside of science. It really struck me that organisms can measured a biologically. That was very shocking to me and I just really got attracted and I want to see why does this happen? What is the effect of different times of day and I just stuck with it. It's just
It was mind-blowing for me, who was in medical school that I've never heard about it before. You know, it's really amazing medicine. I think still. Now we are very good at looking at stuff spatially, but we're very bad at looking at temporal aspects. So we always, you know, like to see images static, images spatial
information, take an x-ray measure, a temperature, measuring blood pressure has a clear, but we don't think of them
Paul and and, you know, you talked to John Hogan has right now and he's telling you the
Is of Chrono medicine or Chrono farmer Farmer to whatever the word is. And it just it really just getting the drugs at the right time of the day is going to be essential for our health. Do
you think that's going to come from using better trackers like or rings? Whoops, traps? These kinds of things. I loved the
trackers, but I think there's even more exciting discoveries. Now, you could take a single blood sample, and measure many, biological components and figure where you are in the circadian clock, something.
That was very hard to do before. So if you have a marker to know where you are in the clock, you could actually understand more the effect of everything exercise feeding, light input. What is the marker? So there are some papers from what's-her-name, Phillies Z and from cream creamer, where they measure multiple rnas that are known to tell you what phase of the clock is, or multiple proteins or biological reactions. And depending, on a
A fact and not a single Factor, you could tell where you are in the circadian clock. So they could instead of just measuring temperature or melatonin just one measurement. And melatonin specifically is also Complicated by the fact that melatonin is affected by light. And, you know, and temperature your temperature and sleep can be easily dissociative. All right, when you travel across different time zone, you sleep at different times in the temperature cycle. So having multiple components, measured will give you a better determination of your
radiant face and understanding your circadian phase in. Humans will tell you what is the effect of giving certain drugs at certain times of the Circadian phase. So in the future, this is going to be studied at a much higher level when you can determine the phase in relation to all the other stuff.
It's striking to me that in all animals, besides humans, if they deviate Too Much from the appropriate exposure to light and Light Dark cycle. They essentially don't mate and or die and or get killed off, but in humans, we are able to override that at least to some extent, but the ways in which we suffer appear to be things like obesity, metabolic syndromes reproductive syndromes that are
The other syndromes, you know, endocrine syndromes and mood and depressive disorders. Is there any effort at the level of the nationally or or Laboratories that you're aware of to try and use light in order to improve mood and mental
health? I mean, honestly, this is my mucho. This is the thing that I think people because it's so I say don't take your pill take a photon and not I mean you take pills it's important. I'm just making it that really we have.
An opportunity right now with that incredible advances of LED lights of changing spectrum of light of regulating intensities and just to associate Justice for simple changes. You could really improve sleep-wake cycle productivity, and still you could actually get more done because as we've talked about when you have all these messed up, now, you have to sleep more, but your sleep is fragmented. It's not very good and you can't focus and you can sit.
Because we don't have alertness when you need the alertness. So having all these, you could allow you to do even more actually at the end than less and that's the exciting part
of it. One of the questions I get asked most often about is about ADHD, you know, I think there's a lot of self-prescribed as well as clinically prescribed. ADHD people are having a tremendously difficult time focusing. And not, just because they're sleepy. They just can't seem to Anchor their attention. And there could be multiple reasons for this, but there are now several clinical trials.
Isles ongoing using light to try and anchor, people's attention, and mood and well-being for sake of focus. And I think that while I love this saying that you mentioned, you know, take a photon not a pill and with due respect to the need for pharmacology for certain people think, most people just haven't really dialed in their relationship to light in a way that allows them to rule out whether or not they need obstacle Asian.
Absolutely. That's the best way to put it. I can't add to that.
Let's talk about jet lag but not in the context of, okay, if somebody's traveling from Europe to Japan, or from the East Coast because that varies tremendously, right? I mean, there's as many different variations on travel as there are individuals out there and goals, and jobs, Etc. But rather, let's talk about what are the two or three things that people can do to adjust their schedule quickly. Yesterday. I called you and said, look, I know somebody who's traveling 6 hours. I won't even.
In which direction because I don't want people to Anchor to that example. And you describe some very simple tools of viewing light, a little bit earlier than normal and getting on the local food, schedule, Etc. That would allow them to shift more quickly. And the reason I want to have this conversation is yes, for The Travelers. And for the, the shift workers, but mostly, because of the fact that you've proven again, and again, that people are disrupted in their circadian.
Ian Behavior at home. So what are the aside from what we've already talked about? How can one adjust quickly to a new schedule? Like let's say fall classes are starting you start a new job or you have a baby or a puppy or whatever. What is the best way to shift the clock
quickly? So it's very simple as we've talked yesterday. So, imagine you're in the outside with no environmental with no industrial Light.
If you if your body thinks you're in early evening, and you see a bright light. What does this tell you? Oh wait, this is not early evening yet. It's still early afternoon or late afternoon. So I have to delay my clock to go back to late afternoon. So if you get light early in the evening, it delays, your clock.
So what does mean you that makes you want to go to sleep later?
Yes, it delays. Your clock. So so you're in New York.
Right? People in Italy have an advanced clock because they are six hours ahead of us. So if you're in New York and you get light early in the evening your delay even further from Italy. So now you're delaying away from Italy. Now, the same thing happens. Let's say you thought don't came up and you thought it's already done, but it was, let's say three o'clock in the morning or four o'clock in the morning, and then you get a bright light and you say, oh, wait a minute, don't it's not up yet.
So, I should Advance my clock or I'm at night, but I'm getting bright light. So I should run because Dawn is already up. So, then later in the night later in your night and actually just happens that humans you get a temperature nadir later in the night air flow temperature in your body. After that light start advancing your clock. So if you want to go to Italy, instead of getting light early in the evening, you want to get light after the
temperature low, so you could Advance your clock even before you go to Italy, then you're catching up to the Italians just by using like it's as simple as that great. So you could do it for every region, you could calculate how much they are Advanced of you. You could know how much these light shifts happen per day and you can calculate what you what you need to do very simple math to adjust either in direction of delaying. If you're going from New York to California, you want to delay your clock or advancing. If you're going from New
York to,
Chubby,
so, in order to make that a visual and because a lot of people are listening to this not looking at on video, we will put a down, a zero cost downloadable figure of this on the huberman lab.com website related to this episode, but I think I can summarize it in in language as well. If I understand correctly, what you're saying is
If your typical wake up time is say 7:00 a.m. Then your low point in temperature probably occurs somewhere around 5 a.m. And if you view light right orbit around, then it's going to essentially Advance your
clock because then you your buddy think. So. It's 7 o'clock. Still Advance your clock by one to two
hours. But if I were to view like say at 3 a.m. Then it would probably delay my clock. Yeah. Okay. Yeah, so and then let's say I land in a new schedule.
Want to adjust to new schedule. Let's say, I didn't manage to do anything with my light viewing before I went and I didn't, I didn't anticipate the trip. Suddenly. I'm on a new schedule. Okay, I was told that one of the ways to help shift the clock and to avoid gastrointestinal issues is to eat on the local schedule to start basically behaving like a local, even though your circadian clock will take a little bit of time to catch up.
Absolutely, but you have to remember the light, right. So let's, let's now that we explain.
That very simply. Let's take a very simple example, right? New York to Italy. That's a simple example, New York time, Italy, time six hour difference, right? So let's say you fly from New York at night. You reach Italy, at eight o'clock in the morning. What is the time in your New York time? You, although you
reject hours back, six hours to and then it's 2 a.m. So
when you land Italy, you want to avoid light like the plague. Yeah, you could eat but you really don't want to
get a lot because otherwise it's going to delay that delay
is going to
And you to California instead of sending you to Italy, right? And so this is such a key point. If anyone's
confused about this, we will put some diagrams up. But what Sam are saying is so crucial just because getting bright light in your eyes, early in the day is really beneficial when you're at home. When you travel to a new time zone, you have to take into account what your body thinks, what scuse me, you have to take into account where your body thinks you are. And so, if you're looking at the Italian Sunrise, having just flown from New York to
Italy and you didn't prepare for that trip by waking up a little bit earlier in anticipation. Multiple days. You've you light it to a, excuse me at 6:00 or 7:00 a.m. Italian time. Beautiful Italian Sunrise. You are going to delay your clock. You're going to basically throw yourself back to California, but you are in Italy. You're gonna throw your biology back to California and you are going to be up in the middle of the Italian night and you're going to be a miserable miserable. I'll tell a brief and it took us like called sammer in desperation a few years.
Ago, I traveled to Abu Dhabi, NYU Abu Dhabi to give a seminar 12 hours out of Faith. It's a 12-hour flip and I thought I could just muscle it. I thought I'll get up just view sunlight when the sun comes up, and I fell apart, mentally and physically and Samer came to my rescue. I call them. I said, I don't know what to do. And he said, go to the gym. Went at the local Dawn work out eat and then view sunlight.
Starting the next day and that basically got me on the schedule. So I used food and exercise to adjust myself because my light viewing activity was just completely out of
whack. Yeah, I mean, I know we talked about other details so you have to calculate it, but you're absolutely right. I mean, it's it's very important to avoid getting the wrong light information when you're trying to adjust your body because otherwise it shifts you to the other to the other side. Absolutely
well,
You are one of these people that has such Vigor. It's one of the things we're having known you all these years. You have a tremendous capacity for work and for soccer and for arguing respectful arguing and you know, sometimes, you know, it's getting worse with age. Yeah. Well, we could talk about that offline, but I think a lot of your Vigor and a lot of your ability to work hard and focus and really do so many things at an impressive level is because you think about these issues and you you think about when you're going to
Optimal for focus when you're going to be optimal for exercise. When, and the, when is the key. It's and I think a lot of people live in the landscape of feeling like, there's something broken inside them, because they can't focus, or
they could have two inches, right? Remember, it's all subconscious these effects and Hunter. You're absolutely right now. Honestly, joking aside about age. I really agree with you that. I think part of the reason I'm continuing to be able to do this, that I really think about it and I make sure that I keep
Everything. Aligned and, and that actually helps me a lot. Like, I don't suffer in sleep. I don't suffer in waking up. I never use a timer to wake up. I mean, people say, aren't you scared like you have to give a lecture at eight or 7:30? Honestly, I was like there is no way I'm gonna go beyond that, it just even if I try. I can't sleep Beyond 6 a.m. In my regular times. It's just, it's not gonna happen by 4:30. My eyes are wide open awake and I'm in bed. It's just system is so aligned it work.
A lot of times people will say, how come I go to sleep? I fall asleep. Fine, but then, I wake up at 3 or 4 in the morning and can't fall back asleep. Is it possible that those people were supposed to go to bed at 8:00
p.m. It's possible. I mean, it is possible. It is also possible that sometimes people will wake up and go back to sleep. But but yeah, I mean, it is possible or it's possible that their clock is completely misaligned, that they are getting maybe enough time at night when they are supposed and then they possibly feel so sleepy in the day. So they're all these
Possible combination. And that's interesting idea and considered. So, I mean that what they think is their sleep, their body is so out of whack with the light-dark cycle that it's actually a
Nana or the weaker part of the sleep. I mean, you see this in in when you travel to different time zone before you adjust, you go to sleep really well, but two hours later, you're fully up two hours if you were so tired. And this is your regular sleep. There is no way you're going to wake up in two hours. So then you feel very sleepy.
Up later in the day or something like that. So it depends of how your whole system is aligned to the
environment. That's very interesting idea. I think that's going to resonate with a lot of people I wake up every morning around three or four generally use the bathroom and then I fall back asleep. Very very deeply doesn't seem to disrupt my daytime wakefulness. And I think a lot of people obsess over the that waking up and were either something wrong provided. They can go back as exactly if it's okay.
If you can go use the bathroom go.
Sleep. That should not be a problem. Maybe, some people when they go to use the bathroom. They use very bright light and then they get an alerting signal. So if you maybe that's it, could be as simple as that, that affects you. Maybe when you wake up, you put tons of light or you start reading your iPad. So there's all these combination that we still don't know about. That could be affecting their sleep-wake Rhythm Xander. Sleep
maintenance do use. Melatonin do take melatonin.
I don't need it. To be honest. In my case.
There is no reason to use it because I could guarantee you that by maybe eight o'clock my marathon and has already started to go up. And by the time I sleep, my melatonin is very high because I don't use a lot of lights after Sunset and light inhibits. Melatonin life's really blocks melatonin
level, but you hear this, myth that the pineal gland a calcifies as we get older. Is that, you know, anything about? I mean, I've heard
about that, but I don't know how what does I mean. There is not very clear evidence that affects the sleep.
I don't know
much about it, to be honest. The evidence that I've seen is that, yes, there's some calcification around the pineal, just because of where it sits in the in the brain. It's close to some bony bony structures, but I don't think there's any evidence that it has negative effects that
mean, if you still have, you could measure minute on and that should tell you, if it has nothing. It's such an easy thing to do.
I think this is more of a internet. Wellness thing that thumbs, but that got outside the cage. You're absolutely right.
Uh, yeah, it sounds terrible calcification. Yeah, that's not the thing. Right? The hard thing, right? Yeah. Exactly. Let's talk about seasonality a little bit. I learned. And I don't know if this is still true, but that most suicides occur in April in the spring. I think there's a poem that says April is the cruelest month. I think it B is the poem begins.
Are there data that suicides are more frequent. It's a particular times of year. And if so is the spring that time of
year. Yeah. I mean a lot of people talk about this and one of the hypothesis that is that the winter month that are very bad for mood, make people not wanting to do anything and they have, they get into such deep level of depression. That when the sun comes up, they get actually the energy to act on their depression, which sounds really terrible. And it's just a noble gesture. That's
So that's the idea that the lack of light throughout the winter cause them to go into such depression that they don't feel like doing anything. And when the light comes in with rigor, in the spring, it gives them that. After all, the depression, they suffered. Give them that push to to take that sad final, you know act. I
guess what other seasonal effects have been demonstrated in human.
Yeah. I mean I think in humans is not very clear because we don't think about seasonality but if you start
Thinking about us. I think we go through major seasonal changes. I really do. I think our eating pattern change across there. I could tell you that me thinking about this. There is a clear changes that happens to me across the year, but for Animals, this is really essential because for animals, they have to time their mating behavior with when they deliver their their progeny in the most abundant amount of food and artificial light is causing major disruption.
Because if you change the way these animals are receiving the light information, they either start mating much earlier or much later and their numbers dwindle and they get into the dangers of really completely getting eliminated or
extinct, human. Birth rates are definitely going down. I mean in the u.s. In the u.s. Example. Yeah, not a right, but are there other effects of seasonality on humans that were aware of?
I honestly, like, you could.
It honestly you could see it perfectly I think in in Scandinavia. I mean you could talk to people in who live
in sure. They get seasonal depression,
what season depression is one? But actually when you start asking them questions, they tell you like in the winter, they barely could wake up. They barely have the energy for even depression. Even people who don't get seasonal depression. They'll tell you our energy level is lower. Our ability to go to work is is not the same. And in the summer, most people actually
I sleep very little they tell you we really can we feel like we're manic? We have all this energy and nothing in negative way in a funny way, right? I mean, but if you want to sleep, we have to put the skirt and I think in these situations you could really appreciate the seasonality of humans. I think we kind of destroyed our seasonality because we don't get exposed to that much natural light. We have all this artificial light, but I think honestly, one of the
That is going to happen if they follow you recommendations about giving light at the same time, giving food
giving extra. Let's be clear. Those are your recommend. Well, I mean, I'm just I'm just fair attribution. What
I'm saying is that this is gonna cause them to also experience some changes across the season because now they going to see the sun differently. If you're going to go out in the morning in the summer, you're going to get the much broader. That's why I don't like the change in time. I know people think. Oh, because your bias.
Just you because I think we
wait. Sorry, the change. Are you talking about daylight savings,
Daylight Saving? It's such a bad idea because it disrupts that Rhythm that you're having because I think your body if you keep that Rhythm, you will see the whole seasonality and I look at it from a different aspect than other people. It really. And people say I'm biased because I'm a morning person and it may be true but this
situation conspiracy but morning people. Yeah, but this is
if you think about it, and they
A situation where you're getting like perfectly well, and then all of a sudden they delayed by one hour because and then even though it's the summer, your body, now if you're still not adjusting think, oh wait, what happened? What kind of happened?
Well, I'm glad you're bringing this up because I always thought you know, what's the big deal one hour, right? One hour shift, you know, spring forward fall back, just one hour act, but the but this goes back to the beginning of our discussion. It's not just one hour, right?
Because it's one hour across that one day, but there's this cumulative effect on the clock and these three elements of your tripartite model, if the homeostatic sleep and the like Direct effects on food, and when it's
so close, it's sometimes hard to figure out how to adjust it perfectly, because, you know, we're already sleep deprived in our society and then you shift it by, you know, so it just it all accumulates. And it has no
benefit when you work at a major government organization, National Institute of Mental.
Health, why don't we campaign for?
I have no idea. I mean, it makes
no, I'm saying why don't we go campaign? Yeah, I'm
gloves do. I mean it makes no sense to have the summer. Light goes up at 9:00 p.m. The light goes down in where I live in Baltimore at 9 p.m. And then all of a sudden when you really want to see the light longer in the day, you now shift the other way and now it goes origin at six pm. Why do you do this? Drastic changes? We'll let it blend across the whole season. You
No, yes later earlier at night, but it's at least consistent. It goes in a very consistent manner. I just don't understand why they do this. It makes no
sense. Well, I think that the reason they do it is because they don't understand the biology because one hour seems trivial unless you understand that the repercussions of that one hour shift because what's also clear? Now based on what you're saying is that, that one hour shift is taking you out of alignment with the natural light dark cycle in exactly the wrong.
On
direction is pushing people to get even later in the summer when light is going to push you later. Anyway, it doesn't make sense. You put it beautifully. I just rambled, and this is,
oh no! You made it, you made it clear. I mean,
it's like, literally it made you. It made people who are having problem having an advanced sleep Rhythm because they are delayed. Now you give them this hour to make them even more delayed, you push them even later in the day night cycle. It just doesn't make sense at all.
I think 2022 should be the year that we abolish and daylight saving the day for me. Honestly. Well, it's end. Well also, if it has a positive effect on the what is essentially an epidemic of mental health issues and other issues related to improper interactions with light that I think is a well worthwhile cause and can we can explore. So for once we're going to fight with some with another group common battle as opposed to
This is cadmium people honestly to give them credit have been trying for years to abolish daylight
saving. The other problem is, they all go to sleep at 9 p.m. And wake up at 4 a.m. So we never see them. That's right. No, the Circadian Community has done an amazing job of figuring out what we need. Right? And then the challenge of course is making sure that people get what they need, right? And making sure that at a societal level. We're not involving ourselves into the realm. The
biggest problem. Is that the
The late waking people. They think that really and I'm going to try to put it in a better way. Now they think oh because you're a morning person, you want to see the sun early. So you want me to suffer it dropping late, but that's not the case because what happens is when they shift it back after the daylight saving, now they're going to make you suffer really badly because now it's going to be earlier, right in the fall in the fall when there's not enough light, if they keep it the same way.
Try to convince them that actually this at the end causes more trouble when you need the light for your late schedule in the fall, when they shift it back, then they say keep it daylight saving all the time and that has been proven that is very bad. Like people have done studies. That literally two areas close to each other's and areas that were the whole year on Daylight Saving. Has much more problems, even in cancer rates and depression. So you don't want to do
Do that. So that's what trying to convince people that you need to prevent that switch and you don't need Daylight Saving at all. That's where the problem happens,
interesting. I had not thought about that. But yes, you late risers that in the fall, when they, when this the fall back as they say, spring forward fall back. You dial back, the clock. It's really compounding. The problem that already exists,
and it's really nice. If you think, if you keep it consistent in the spring, you get the law.
You know, when you get the equinox and then the day start going up and then, even in the summer, start going down and then the fall you get the other Equinox and go back. So it's very symmetrical, right? It goes into short day, longer long long, long and short day again, but now you're getting these bumps in both sides of the spring and fall. Why would you do that? Something that is beautifully symmetrical, beautifully Smooth. You're
putting bumps into it. Well, and we not just beautiful because it's there, but but
What evolved? I mean, essentially this is the system we evolved in for seasonality is almost a year,
even apart from the exact equator, every part of the Earth have seasonality.
I want to briefly touch on something which is individual and genetic variation in sensitivity to light. So not Chrono tight, but first of all, very basic question. Do people with light eyes, light colored eyes. Have, are they more sensitive to light than people with darker pigmented eyes. I
mean, honestly, it makes sense. They would be more because if you think of my dark pupil, it's blocking more light. So if you have like
Pupil yes, for vision. It may not be very obvious. But for something that is measuring the amount of light, you getting more like than me, so you're probably need less lie to be effective as somebody who's darker and and that maybe could explain why sometimes lighter people say, I don't want to go into very bright conditions because it's really
bright. Yeah. I can't, I can't even be at a cafe with a one of these reflective tables, like a metal table unless I have very dark sunglasses. Exact so bright. It's painful.
Right, whereas, some people like you, we sat outside, yeah, meals. And you're like, fine. I assumed it was kind of Jordanian toughness, you know, versus, you know,
it's really the pupil blocks more light. So I think it is possible that it's, as simple as the pupil blocking, more light can have sensitivity, but your question is also goes deeper are there, more sensitivity differences on and my understanding would be, I would think that it may be depends on how effective your cells aren't responding to light how healthy your I prg.
He's our. So I would but there's not many studies to show that what is really clear that is happening, is that patients with bipolar? They seem to have different sensitivities to light. So it seems that at least people who have psychological changes. They may have differences to the sensitivity of light. So
where are those differences in a particular direction? I don't remember the exact well after we can look it up. Yeah. Yeah.
Yeah, I, you know, I and people have heard me say this ad nauseam to the point where they actually roll their eyes, but you know that these are the only two pieces of brain. I'm pointing to my eyes folks that are outside. The cranial Vault. They are two pieces of brain that it basically inform the brain about whether or not to be alert or asleep should. But you can imagine that those two little pieces of brain that we call eyes, would have genetic variations across eye color is genetically. Module is that determined that there would be genetic variations based on whether or not
Your ancestry evolved near the equator further from the equator, right? I mean you see more blue eyes in Scandinavia, unless you do it. I mean, it's the
lack of light that said you need more or less inhibition because there is not enough light, right? So that's the idea of the changing color. So yeah, I totally agree with you. I mean, I think this is an area that will be studied later and we'll be empirically. Determined the problem we have in this field right now, which I think is the biggest problem.
Is we don't have a way to measure the IPR juicy sensitivities in humans. So we still like, it's easy to measure your Rod corn function. If you go to an optometrist, they measure all the details. Right. Contrast detail.
Look at the Char. You let's count all the snow and Charlie, look at the letters at the DMV. Yeah,
but for the non subconscious, we still don't have a good measuring systems to figure out what is Andrew sensitivity. What is summer sensitivity? What is this person sensitivity? And I think
We're starting to work on something like that to hopefully develop these techniques but till we develop them is going to be very hard to figure out. If there is a sensitivity difference. How do they relate and on men and women, you know, dark and light and all the, you know, normal versus psychologically and effect and stuff
like that. Fascinating. And every time you talk, I learned so much. It's like a in the best way, the best sense of the term.
Termites. It's a waterfall of knowledge as a final question. I have a question about sensitivity of a whole other kind, and that's the sensitivity to spicy food. Now, the reason I'm asking this question, what seemingly out of the blue is that I made the mistake once of having Samurai cook for me and I said not too spicy and he said, okay. Not too spicy. Yeah. She's at. Okay. Not too spicy and it,
Almost killed me. I always like two or three days. So,
you know
a lot about biology outside the visual System Light Etc. You've been around while are there known genetic or inherited of any kind sensitivities to spicy food to things like red peppers and capsaicin? Because what you call Mild, my friend almost put me into the hospital. I think this is
similar to your swimming in the ocean and I need to get
Up the pka,
true. True. I like cold water swims and say there's not a fan, but that's how change it's adaptable. That's going to change
before I met Tracy, I was like you, and and once I started eating a lot of spicy food. I lost touch of how spicy my food is so I nearly killed you and Ron I apologize.
I forgive you. So basically what you're saying is that marriage toughen you up. Definitely not exactly. Maybe that's maybe that's the special. Yeah Samer. This has been an amazing.
Saying March through the importance of light, not just for regulating sleep and wakefulness, but also for food timing, the interactions with mood, the interactions with exercise. I'm certain that people are going to start thinking about how to change the relationship with light as a way to Anchor, everything that they do, and that's important to their health. And I just on behalf of all of them and just directly from me as your friend and as a colleague for many years now, I just want to say,
Thank you for the incredible work, you're doing and for sharing it with
us. Thank you so much. And I actually know thinking about all of this. And you said I should write a book. I should write a book and call it the tripartite model. I think that would put all these components together would be very interesting to do. At some point.
You should write a book. You should write, they'll probably try and change the title to like food mood and you you know something because but you can put in little printer the tripartite model or whatever. But regardless of what it's
Old I you absolutely should write a book. And so if you'd like Samer to write a book or if you'd like to learn more about him, let's talk a little bit about where people can find you. Your Laboratories of the National Institutes of mental health. He is head of the chronobiology unit. All these things that I've mentioned earlier, but you are active on Twitter and Instagram, right? So, what is your Twitter handle? It's at some more Hot Tar and we will provide a link for that in the show notes
so that yes at the Twitter at summer Hector and I think
The same for Instagram actually, and
simmer has been coaxed on the Instagram. So he does post from time to time. Mostly pictures of food. That is incredibly spicy and but also information about chronobiology, he comes on for an Instagram live, every once in awhile with me. And so, definitely give him a follow their, and, and on Twitter and, and I'm sure that he'll be happy to answer questions and didn't entertain any and all discussions about chronobiology.
Click upon light. Yeah,
great. Thank you Sandra. Awesome. Thank you and Roy. Thank you for joining me for my conversation, with dr. Samurai, Qatar. I hope you found it as interesting and informative as I did. If you're enjoying this podcast and we're learning from it, please subscribe to our YouTube channel in addition. Please leave us comments and feedback in the comments section on YouTube. A great thing to do, there would be to make suggestions about future topics. You'd like us to cover, or future guests. You'd like me to host on the you
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