Using Light (Sunlight, Blue Light & Red Light) to Optimize Health
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Welcome to the huberman lab podcast, where we discuss science and science space tools for everyday life. I am huberman and am a professor of neurology, gy and optio logy at stanford school of medicine. Today, we are going to discuss light and the many powerful uses of light to optimize our health.

We are going to discuss the use of light for optimising skin health, appearance and longevity, for wound healing, for optimizing hormone baLance and for regulating sleep, alertness, mood and even for offsetting dementia. One of the reasons why light has such powerful effects on so many different aspects of our biology is that IT can be translated into electrical signals in our brain, in body, into horn signals in our brain and body, and indeed into what we call cascades of biological pathways. Meaning light can actually change the genes that the cells of your body's express.

And that is true throughout the lifespan. Today, I will, the mechanisms by which all of that occurs, I promise to make IT clear for those of you that don't have a biology background, and if you do have a biology background, i'll try and provide sufficient death so that it's still of interest to you. And I promise to give you tools, very specific protocols that are extracted from the pure review literature that will allow you to use different, so called wavelength, which most of us think of his colors of light, in order to modulate your health in the ways that are most important to you.

For those of you, they are thinking that the use of light to moderate health falls under the category of woo science, pu du science or biohacking. Well, nothing could be further from the truth. In fact, in one thousand nine hundred three, the nobel prize was given to neil sinson.

He was islands. He lived in denmark for the use of photo therapy for the treatment of lupus. So there's more than one hundred years of quality science emphasizing the use of light, and as you assume cy, the use of particular wavelength or colors of light in order to moderate the activity of cells in the brain and body.

So while IT is the case that many places and companies are selling therapies in products related to the use of flashing lights in colored lights, promising specific outcomes from everything from stem cell renewal to improvement in a brain function, and some of those don't have any basis in science, there are photo therapies that do have a strong foundation in quality science. And those are the studies and the protocols that we are going to discuss today. But I thought that people might appreciate knowing that over one hundred years ago, people were thinking about the use of light for the treatment of various diseases and for improving health.

And indeed, many of those therapies are used today in high quality hospitals and research institutions, and, of course, clinics and homes around the world. One of the more exciting examples of phototherapy in the last few years is the beautiful work of doctor glen jeffrey, university college london. The Jeffery lab is known for doing pioneering and very rigorous research in the realm of visual neuroscience, and in the last decade or so, they turn their attention to expLoring the role of red light therapy for offsetting age related vision loss.

What they discovered is that just brief exposure to red light early in the day can offset much of the vision loss that occurs in people forty years or older. And what's remarkable about these studies is that the entire duration of the therapy is just one to three minutes done just a few times per week. What's even more exciting is that they understand the mechanism by which this occurred, the cells in the back of the eye that convert light information into electrical signals that the rest of the brain can understand and create visual images from.

Well, those cells are extremely metabolically active. They need a lot of ATP or energy. And as we age, those cells get less efficient at creating that atp and energy exposure to red light early in the day.

And IT does have to be early in the day, allow those cells to replace ish the mechanisms by which they create ATP. I'll talk about these experiments in more detail later in the episode and the protocols so that you could apply those protocol should you choose. But I use this as an example of our growing understanding of not just death photo therapies work, but how they work.

And IT is through the linking of protocols and mechanism that we, meaning all of us, can start to apply photo therapies in a rational, safe and powerful way. Before we begin, i'd like to emphasize that this podcast is separate from my teaching researchers. 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 general public.

In keeping with that theme, i'd like to thank sponsors of today's podcast. Our first sponsor is athletic Greens. Athletic Greens is in all in one, a vitamin mineral probiotic drink. I've been taking athletic Greens since two thousand and twelve, so i'm delighted that their sponsor in the cast, the reason I started taking athletic Greens and the reason I still take athletic Greens once or twice a day, is that IT helps me cover all of my basic nutritional need to make up for any deficiencies that I might have. In addition, IT has pro biotics, which are vital for microbiology health.

I've done a couple of episodes now on the so called gut microbiome, and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With deleted Greens, I get the vitals I need, the minerals I need and the probiotic to support my microbes. If you'd like to try athletic Greens, you can go to athletic Greens dotcom flash huberman and claim a special offer.

We'll give you five free travel packs plus a year supply of vitamin d 3k two are ton of data now showing that vitamin three is essential for various aspects of our brain and body health。 Even if we're getting a lot of sunshine, many of us are still deficient in vitamin d three. And k two is also important because IT regulates things like cardiovascular function, cause um the and so on.

Again, go to athletic Greens dcom sa huberman to claim the special offer of the five free travel packs and the year supply of vitamin three. K two. Today's episode also brought to us by element.

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If we have sodium anisim in patashie present in the proper issues, all of those cells functions properly, and all our bodily systems can be optimized if the electricity are not present and hydration is low, we simply can't think as well as we would otherwise. Our mood is off, horn systems go off. Our ability to get in a physical action, to engage in endurance and strength and all sorts of other things is diminished.

So with element, you can make sure that you're staying on top of your hydration and that you're getting the proper ratio of electoral lights. Like to try element, you can go to drink element that element dot com slash huberman and you'll get a free element sample pack with your purchase. They're all delicious. So again, if you want to try element, you can go to element element dot, come slash. Today's episode is also brought to us by waking up, waking up as a meditation APP that includes hundreds of meditation programs, mindfulness trainings, yoga eda sessions and n sdr non sleep depressed protocols.

I started using the waking up up a few years ago because even though i've been doing regular meditation since my teens and I started doing the yoga ea about a decade ago, my dad mentioned to me that he had found an APP turned out to be the waking up APP, which could teach you meditations of different durations, and that had a lot of different types of meditations to place the bringing body into different states, and that he liked IT very much. So I gave the waking up up a try, and I too found IT to be extremely useful, because sometimes I only have few minutes to meditate, other times have longer to meditate. And indeed, I love the fact that I can explore different types of meditation to bring about different levels of understanding about consciousness, but also to place my brain and body into lots of different kinds of states, depending on which meditation I do.

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If you'd like to try the waking up, you can go to waking up dot com slash huberman and access a free thirty day trial. Again, that's waking up dot com slash huberman to access a free thirty day trial. Okay, let's talk about light first. I want to talk about the physics of light, and I promise to make that very clear, even if you don't have a background in physics.

And then I want to talk about the biology of light, meaning how light is converted into signals that your brain and body can use, the impact, things like organ health or disease, or how you can use light in order to repair particular organs like your skin, your eyes, your brain. At seta, the physics of life can be made very simple by just illustrating a few key bullet points. The first bullet point is that light is electro magnetic energy.

If the word electronic magnetic feels daunting to you, will then just discard that and just think of light as energy, and think of energy as something that can impact other things in its environment. Now, the way to imagine light, or to conceptualize light as energy is that all around you, light is travelling in these little wavelength. And the reason for those, they're watching, making a little wave motion with my hand, is that actually the way that light energy moves in little waves, just like sound waves are coming at you and pinching on your ears.

If you can hear me talking right now, that is happening. Those are sound waves mining the movement of air particles out there impacting your ear job well. Light energy is just little bits of electro magnetic energy traveling through your environment all the time in these little waves and in pinching on your brain and body and eyes at setting up.

And as I mentioned before, energy can change the way the other things. Behave, IT can cause reactions in cells of your body. IT can cause reactions in fruit, for instance, right? You see a piece of fruit and it's not ripe, but IT gets a lot of sunlight and IT ripes.

That's because the electro magnetic energy of sunlight had an impact on that plant or that tree, or even on the fruit directly. As a parallel example of energy and its ability to impact other things. We are all familiar with food, and the fact that food has calories, calories is a measure of energy.

IT has everything to do with how much heat is generated when you burn a particular article of food, believe IT or not. And IT turns out that how hot a given article of food burns gives you a sense of how much energy IT can provide your body in terms of your body's ability to store or use that energy. So again, think of light as electronic magnetic energy, but really put that word energy into capital letters in bed that in your mind going forward.

And you'll understand most of the first bullet point of what light is in terms of the physics of light. Now the second thing that you need to understand about the physics of light is that light has many different wavell ines. And the simplest way to conceptualize this is to imagine that cover of that pink fluid album, where there's a prison, you have a White beam of light going into that prism, and then the prism splits that beam of light into what looks like a rainbow.

So you got your red, your orange, your Greens, your blues, your purpose at sea. Anytime we have lighting environment that is so called White light, IT includes all those wavelength sunlight and other forms of light, also have other wavelength light that we can see. So when we think about the rainbow, that's just the visible spectrum of light.

There are also wavelength of light that are not visible to us, but that are visible to some other animals, and that can still impact your brain and body, because there is still energy at those wavelength. Give a few examples of this. Humans are not a species that can see into the realm of the spectrum, a pit viper, meaning a snake, that has informed sensors, however, can sense in the infrared.

So if you were to walk through a jungle and there's a pit viper there, IT sees you as a cloud of heat emission. Because your body is admitting energy. All the time you're casting off infrared energy, the snake can see IT.

You can't. If you were to put on a particular set of goggles that were infrared goggles, well then you would be able to see the heat emissions of any organism, human or otherwise, that could omit info energy. Let's take the opposite element of the spectrum.

We are familiar with seeing things that are blue or Green or very pale blue, but as we say below that, meaning even shorter wavelength is out there. UltraViolet light is a really good example of light energy that's coming from the sun and is in our environment, is being reflected off surfaces all the time. We don't see IT.

And yet if it's very bright outside, that ultraViolet light can burn our skin. As you'll learn today's episode, ultraViolet light and also positively impact us. In fact, I will describe a particular set of new results that showed that ultraViolet light viewed for just a few minutes each day, or landing on the skin for just a few minutes, each shape can actually offset a lot of pain.

IT actually has the ability to reduce the amount of pain sense by your body. And we now understand the specific circuits in the brain body that allow that to happen. I'll talk about that and the related protocols a little bit later.

So the important thing understand about the physics of light is that there's energy at all these different wavelength. We only see some of those wavelength, which basically is to say that light impact us at many different levels. And the so called levels that are referring to are the different wavelength of light.

And you are welcome to think of the different wavelength of light as different colors, but do understand that there are truly colors of light that you and I can see, and yet that have powerful impact on your brain body. Now the third bullet point to understand about the physics of light is that different wavelength light, because of the way that their wave travels, can penetrate tissues to different depths. This is very, very important.

Today, we're going to talk a lot about red light therapies and near infrared therapies. Those are so called longer wavelength oner wavelan. Just think of a bigger, longer wave, right? A bigger curve as a was a short wave light, light, which is going to be shorter, right?

A short wavelength would be something like blue or Green, lighter, ultraViolet light, blue, Green and ultraViolet light, because its short wave live light doesn't tend to penetrate tissues very easily. IT has to do with the way that the physics of light interacts with the physical properties of your skin and other tissues of your body. But basically, if you were to shine uv light onto your ARM, for instance, IT could impact the skin on the surface of the army and maybe some of the cells just beneath the top layer of skin, but IT wouldn't penetrate much deeper.

Long wave late light, like red light and near infrared light has this amazing ability to penetrate through tissues, including your skin. And so if we were to shine a red light or near infrared light onto your ARM, IT would pass through that top layer of skin. IT might impact IT a little bit, but I could penetrate deeper into your skin, not just to the skin layers, but maybe even down to the bone, maybe even down to the bone marrow.

And for many people, this will be hard to concept. Ze, you think, wait, i'll get the skin there, doesn't the light is baLance off and the answer is no, because of the way that long wavelength interacts with the absorbing properties of your skin. Absorbing properties is just the way that the skin takes light energy and converts IT into a different form of energy.

And your skin is not able to take long wavelength red light and near him for red light and absorb bit, but the tissue is deeper in your body can. So if you shine red light or near and for red light onto the surface of your skin, you'll see a red glow there as a reflectance on the surface of your skin. But a lot of the photon energy, the light energy in those longer wavelengths, is indeed passing through those top players of skin into the deeper layers of skin, and can even make IT into the deep layers of your arms.

And as we started a transition from the physics of light to the biological impacts of light, just understanding that the different wavelength light impact our tissues at different levels, literally at different depth, will help you Better understand how light of different colors, of different intensities and how long you are exposed to those collars. And intensity of light can change the way that the cells and the organs of your body work. And if IT didn't sound weird enough, that you can pass light through particular tissues and have them land and be absorbed at tissues deeper in your body, well, IT turns out that different wavelength of light are also best absorbed by particular, so called organ's within yours cells, what organelles organiser, the different compartments and different functions within a given cells.

So, for instance, your meter contra, which are responsible for generating ATP and energy, and yourself ells, those exist at a particular depth, at a particular location within a cell. They are not all at the cell surface. They sit somewhat deeper in the cell. The nucleus of your individual cells contains DNA, and that is at a particular depth or location within your cell.

Different wavelength of light not only can penetrate down into different tissues and into different cells of your body, but they can also penetrate and access particular organelles, meaning by a contra or the nucleus or the different aspects of yourselves that are responsible for different functions. This is exactly important, and it's exquisitely powerful, because as you learn today, particularly wavelengths of light can be used to stimulate the function of particular organisms, within particular cells, within particular organs of your body. I can think of no other form of energy, not sound, not chemical energy, so not drugs, not food, not touch, no form of energy that can target the particular locations in ourselves, in our organelles, in our organs and in our body, to the extent that light can.

In other words, if you had to imagine a real world surgical tool by which to moderate our biology, light would be the sharpest in the most precise of those tools. Now let's talk about how light is converted into biological signals. There are several ways in which that is accomplished, but the fundamental thing to understand is this notion of absorption of light energy, certain pigments or colors in the thing that is receiving the light energy, meaning the thing that the light energy lands on are going to absorb particular wavelength of light.

Now, I promise you that you already intuitively know how this works. For instance, if you were to sit outside on a very bright, Sunny day and you had a table in front of you that was metal, you might find IT hard to look down at that medal table because it's reflecting a lot of light of particular wavelength. Es, if that table were pitch black, however, IT wouldn't reflect quite as much, and you would be able to comfortable ly look at IT.

If that table were read, IT might be somewhere in between. If that table were Green, IT would be also somewhere in between. But let's say, we're very light blue. Well then IT might reflect almost as much as a table that were just metal or a White table surface.

So the absorbing properties of a given surface will determine whether not light energy goes and stays at that location and has an impact on that location, or whether not IT bounced is off. Every biological function of light has to do with the absorbing or the reflectance of light, or light passing through that particular thing, meaning that particular cell or compartment within a cell. I'd like to make a clear hardest works by using the three primary examples of how you take a light in your environment and convert IT into biological events.

We have photo receptors in the back of our eyes. These photo receptors come in two major types, the so called rods, and the comes. The rods are very elongated.

They look like rods, and the cones look like little triangles. Rods and cones have within them. Photo pig men.

They have dark stuff that stacked up in little layers. Roads absorb light of essentially any wave life. There are some variation to that. But let's just say rod's don't care about the different colors of light.

They will absorb light energy, photon energy, if it's red, if it's Green, if it's blue, if it's yellow, doesn't matter as long as that light is bright enough. And IT turns out that rods are very, very sensitive. They can detect very, very small numbers of photos.

And rods are essentially what you use to see in very low light conditions, will return more division later. The comes come in three major varieties, at least for most people who aren't color blind, you have so called red coes, Green cones and blue coins, but are not really red, Green and blue in the back, your eye. They are cones that either absorb long wavelength red.

They absorb medium wavelength light Green or short wavelength light blue. The reason that they can absorb different wavelength of light is they have different photo pigments, so much as the example I gave before, where you have different tables outside in the Sunny environment, and some are reflecting light more than others, others are sorbing light more than others. Well, so too, the photo receptors, meaning the cons, are absorbing light of different wavelength to different extents.

And in an absolutely incredible way, your brain is actually able to take that information and create this perception that we have of color. But that's another story altogether that will just touch on a little bit more later. But that if you want to learn all about, you can go to our episode on vision.

So that's photo setters in the back of your eye absorb light of different wavelength. Robin comes the other place, of course, where light can impact our body is on our surface, on our skin. And skin has pigment, too.

We call that pigment melanin. We have within our skin multiple cell takes, but in the top layer of skin, which is called the epidermis, we have corrected o sites, and we have milano sites. And the melania sites are the cells that create pigmentation of the skin.

And of course, there is wide variation in the degree to which there is pigmentation of the skin, which has to do with genetics, also has to do with where you were born and raised, how much light exposure you have throughout the year, right? So people told the equate to have more milanaise activity than people who located at the north pole. And of course, people live in different locations throughout the earth, regardless of they're genetic background or where they were born.

And so as you all know, with light exposure, those milano sites will turn on genetic programs and other biological programs that lead to enhance pigmentation on the skin, which we call tending. The way they do that is by absorbing U. V. Light specifically.

So with melania sides, we have a very specific example of how a pigment absorbs light of a particularly length, in this case, ultraViolet short wave length light, which in turn creates a set of biological signals within those cells that in turn creates changes in our skin pigmentation. So we have photo sectors, we have milano sites. And the third example i'd like to provide is that of every cell of your body.

And what I mean by that is that every cell of your body, meaning a cell that is part of your bone tissue, or your bone marrow, or heart tissue, or liver or spleen, if light can access those cells, IT will change the way that those cells function for Better or for worse. For many organs within our body that reside deep to our skin, light never arrives at those cells. A really good example, this that will touch on later is the spleen.

Unless you have massive damage to your body surface, unless you literally have a hole in your body, light will never land directly on your spin, but the spleen still respond to light information through indirect pathways, and those indirect c pathways arise through light arriving on the skin and light arriving on the eyes. So a key principle that i'm going to return to again and again today is that the ways in which light can impact the biology of your organ's, yours cells, your organs and the tissues, and indeed your whole body, can either be direct. So for instance, light onto your skin, impacting skin, or light on your photo receptors, impact in the photo receptors of you are or IT can be indirect IT can be light arriving on your photos tors the photos tors than informing another cell type, which informs another cell type, which then release a signal, kind of a bucket bade manner off to the spleen and says to the spleen, hey, there's a lot of U, V.

Light out here. We're actually understand. In fact, there's so much U, V, light that you need to activate an immune program to protect the skin.

And in response to that, the spring can deploy certain signals and certain cell types to go out and start repair ring skin that's being damaged by U. V. light.

So we have direct signals, and we have indirect signals. But in every case, IT starts with light of particular wavelength being absorbed by particular pigments or properties of the surfaces that those lights ves land on. And as you were call from our discussion about the physics of light, remember, it's not just about light in pinching on the surface of your body.

Light can actually penetrate deep to the skin and access at least certain tissues and sells of your body, even though you can see those wavings of light they are getting into you all the time. So perhaps the best way to to wrap this discussion about the physics in the biology of light with a bit of a bow is to think about light as a transducer, meaning a communicator of what's going on in the environment around you, and that some of those signals are arriving at the surface and impact in the surface of your body. But many of those signals are being taken by cells at the service of your body, meaning your milano sides in your skin and the photo receptors of your eyes, and then being passed off as a set of instructions to the other organs and issues of your body, like an impact our biology in very fast, moderately fast and slow ways.

But even the slow ways in which light and impact of biog can be very powerful and very long lasting. Just as a quick example of the rapid effects of light on our biology, if you were to go from a room that is dimly lit or dark into a very brightly let room, you would immediately feel very alert. You might say, no, that's not true.

Sometimes I wake up and it's dark and I kind of stumbled out and it's lighter out in the next room and IT takes me while to wake up. But if we were to move you from a room that was very dark to very bright signal conveyed from your eyes to an area of your brain stem called the locust rui, us would cause the release of a general, similar to the release of a journey. If you were to be dropped into very, very cold water, all of a sun, you just an immediate wake up signal to your brain and body.

That's an example of a rapid effect of light on your biology, not a very typical one, but nonetheless one that has a hardwired biological mechanism. At the other end of the spectrum are what we call slow, integrating effects of light on our biology. So what I mean by that are ways in which your body is taking information about light in the environment, not in the sort of snaps shot acute sense, but averaging the amount of light new environment.

And that average light information is changing the way that your biology works. But even though this is a slow process, as I mentioned before, it's a very powerful one. The primary example of this are so called cranial rythm. Cranial rythm are literally a calendar that exists within your body that uses not numbers, but amounts of hormone that are released into your brain and body each day and each night as a way of knowing where you are in the three hundred and sixty five day calendar year. Now that might seem kind of crazy, but it's not crazy.

The earth travels around the sun once every three hundred and sixty five days, and depending on where you are on the earth, where you live, you are going to get more or less light each day on average, depending on the time of year. So you're in the northern hemisphere in the winter months, days are shorter, nights are longer. In the summer months, days are longer, nights are shorter.

And of course, things change, whether not you're in the northern hemisphere, the southern hemisphere, but none the less. In short days, you have more darkness. That's obvious. And if you understand that light arriving on the eyes is absorb by a particular cell type called the intrinsically photosensitive gangling cells, just a name.

You don't need to know the name, but if you want us to so called intrinsically photosensitive gangling l also called the melon open cell, because IT contains an option, a photo pigment that absorb short wavelength light that arrives through sunlight. Those cells communicate to particular stations in the brain that in turn connect to your so called pineal gland, which is as little peace sides gland in middle of your brain that releases a hormone called military in. And the only thing you need to know is that light activates these particular cells, the intern sicily photosensitive millon ops and cells, which in turn shuts down the production of military in from the pineal gland.

If you think about this in terms of the travel of the earth around the sun across the year, what IT means is that in short days, because there's very little light on average landing on these cells, the duration of melanin release will be much longer because, as I mentioned before, light inhibits IT, shuts down militants a. In the summer months, much more light on average will land on your eyes, right? Because days are longer.

Even if you're spending more time indoors, on average, you're going to get more light to activate these cells. And because light shuts down military production, where you'll find is that the duration of military and release for the panel is much shorter. So militant onan is a transducer.

It's a communicator of how much light on average is in your physical environment. What this means is for people living in the northern hemisphere, you're getting more militant in release in the winter months than you are in the summer months. So you have a calendar system that is based in a hormone, and that hormone is using light in order to determine where you are in that journey around the sun.

Now, others is beautiful, at least to me, is beautiful, because what IT means is that the environment around us is converted into a signal that changes the environment within us. That signal is melanin. And military in is well known for its role in making us sleepy night, allowing us to fall asleep.

Many of you have probably heard before, I am not a big fan of military and supplementation for our number reasons, but just as a quick aside, the levels of milestones that are in most supplements are far too high to really be considered for sio logical. They are indeed super physiological in those cases. And military, I can have a number different, not just related to sleep, but that's supplemented military.

Ona, here, i'm talking about our natural production and released a military according to where we are in the three hundred and sixty five day calendar year. Original military onan, meaning the military, and that we make within our bodies, naturally not military. In that supplemented has two general categories of effects.

The first set of effects are so called regulatory effects, and the others are protective effects. The regulating effects are, for instance, that military can positively impact bone mass. So militants in can, for instance, turn on the production of osteopathic are essentially stem cells that make more bone for us, that make our bone stronger, and that can replace damaged aspects of our bone.

Meletine a is also involved in natural of the gone ads during puberty, the others and the testes, although there the effects of militants in in to be suppressive on maturation of the over in testes, meaning high levels of melatonin, intend to reduce testicle volume and reduce certain functions within the tests, including sperm production, and to stop term production and within the others miltonic can suppress the maturation of eggs. Etta, I don't want anyone to get scared if you've been taking melatonin. Most the effects of military and on those functions are reversible.

But I should point out that one of the reasons why children don't go into puberty until particular age is that Young children tend to have chronically high endogenous melatonin, and that is healthy to keep them out of puberty until it's the right time for puberty to happen. So mtoni can increase bone mass, but reduces gonads mass, so to speak. It's going to have varying effects depending on the ratios and levels of other hormones and other biological events in the body.

But as you can see, military and has these powerful regulatory effects on other tissues. I should also mention that milestones is a powerful modulator, a pleasant tal development. So for anyone that's pregnant, if you're considering militants in supplementation, please, please, please talk your O B G Y and talk to your other doctor as well.

You want to be very, very cautious because of the powerful effects that militant ic can have on the developing fetus for people that are not pregnant. In fact, all people melatonin has a powerful effect on the central nervous system as a whole, your brain and spinal corda of the major components of your central nervous system. And melatonin, because it's associated with darkness, which is just another way of saying that light suppresses militants in malta in is thereby associated with the dark phase of each twenty four hour cycle.

IT can have a number of different effects in terms of waking up or making our body feel more sleepy. And IT does that by way of impacting cells within our nervous system, literally turning on certain brain areas, turning off other brain areas. And IT does that through a whole cascade of biological mechanisms.

A bit too detail to get into today. So melatonin is regulating how waker sleep we are. IT tends to make us more sleep.

Incidentally, it's regulating our timing of puberty, and it's regulating how our go ads, the testimony overs function, even an adult to some extent, and its regulating bone mass as emotionally four malta, and also has protective effects. IT can activate our immune system. IT is among the most poor anti oxidation.

So IT is known to have certain anti cancer properties and things of that sort, which is not to say that you simply want more melatonin. I think a lot of people get misled when they hear something like military in has anti cancer properties. That doesn't mean that just cracking up the levels of milestones by supplementing IT, whereby spending time in darkness ness and action ani light, which would of course inhibit military and is going to be beneficial for combating cancer.

That's not the way IT works. IT is actually the rise and fall of military in every twenty four hour cycle, and the changes in the duration of that melanthon and signal throughout the season that has these anti cancer and anti taxed in effects. So when we think about light impacting our biology, the reason I bring up malta a as the primary example of that is a because militant, an impact so many important functions within our brain body, but also because hormones in general, not always, but in general, are responsible for the slow modulator y effects on our biology.

And so am using, this is an example of how light throughout the year is changing the way that you're the different cells and tissues and organs of your body are working. And that means tonic is the transducer of that signal. So at this point we can say light powerfully modulates melotte a, meaning IT shuts down militants.

Ent melotte a is both beneficial for certain tissues and impressive for other tissues and functions. What we do with this information, well, it's very well established now that one of the best things that we can all do is to get the proper amount of sunlight each day. And by proper, I mean, appropriate for that time of year.

So in the summer months where days are longer and nights are shorter, we would all do well to get more sunlight in our eyes. And again, it's going to be to our eyes because, as you recall, the panel el sits deep in the brain, and light can access the panel el directly, at least not in humans. So in order to get light information to the pioneer and thereby get the proper levels of militants, ona, according to the time of year, we should all try get outside as much as possible during the long days of summer and spring, and in the winter months, IT makes sense to spend more time indoors.

For those of you that suffer from seasonal effective disorder, which is a seasonal depression or fuel low during the fall in winter months, their ways to offset this, we did entire episode mood and circling rythm where we described this. So IT does make sense for some people to get more bright light in their eyes early in the morning and throughout the day during the winter months as well. But none of less changes in military and meaning changes in the duration of military and release across the year are Normal and healthy.

So provided that you are not suffering from depression, it's going to be healthy to somewhat modulate your amount of indorsing outdoor time across the year. The other thing to understand is this very firmly established fact, which is light powerfully inhibits melatonin. If you wake up in the middle the night, and you go to the bathroom and you flip on the lights, and those are very bright overhead Flores's lights, your military in levels which would ordinary be quite high in the middle the night, because you've been ice closed in the dark, presumably will immediately plump to near zero or zero.

We would all do well, regardless of time of year, to not destroy our military in in the middle the night in this way. So if you need to get up in the middle night and use the restaurant, which is a perfectly Normal behavior for many people, use the minimum amount of light required in order to safely move through the environment that you need to move through. Militants in needs to come on early in the united actually starts rising in the evening and toward sleep.

But then as you close your eyes and you go to sleep, military and levels are going to continue to rise, at least for several hours into the night. Again, if you get up in the middle, I really try hard not to flip on a lot of bright light. If you do that every once in a while, it's not going to be a problem.

But if you are doing that night after night, you are really disrupting this fundamental signal that occurs every night regardless of winter, spring, summer in SATA. And that is communicating information about where your brain and body should be in time. And I know that's a little bit of a tRicky concept, but really our body is not meant to function in the same way during the winter months.

The summer months, there are functions that are specifically optimal for the shorter days of winter, and there are functions that are specifically optimal for the longer days of summer. So again, try to avoid bright light exposure to your eyes in the middle of the night. And for those of you they are doing shift work.

What I can say is try and avoid getting bright light in your eyes in the middle of your sleeping ycl even if you're sleeping in the middle because you have to work at night. If you wake up during that about to sleep, really try hard to limit the amount of light, which is going to be harder for shift workers, right, because they're generally a lot more lights on and bright lights side. You you would want to close the blinds and limit artificial light inside one way to by pass some of the inhibitory effects of light on melatonin is to change your physical environment by, for instance, dimming the lights.

That's one simple way, very low cost way. In fact, you'll save money by doing the lights are turning them off. The other is if you are going to use light using long wavelength, because, as you recall, these intrinsically photosensitive million ops and cells within your retina that convey the signal about bright light in your environment to impact melatonin, to shut down military and respond to short wavelengths of light.

So red light is a long wave length light. You now understand that from our discussion about the physics of light, and if you were to use Amber colored light or red light, and even Better, dim Amber or dim red light in the middle the night, well then you would probably not reduce militant in at all, unless those red lights, Amber lights, are very, very bright. Any light, provided its bright enough, will shut down militants in production.

One final point, about millions in, and this relates to military supplementation as well, is that now that you understand how potently melatonin can impact things like cardiff asked lar function, immune function, anti cancer properties, bone mass go add function at sara, you can understand why that would make sense to be cautious about military and supplementation because supplementation tends to be pretty static. It's x number of milligrams per night, whether Normally indulge ously the amount of militaria that you're releasing each night is changing according to time of year or if you happen to live in area where there isn't much change in daylight across the year. So for instance, if you live near the equator, well, then your body is a custom to having regular amount of military in each night when you start supplementing military and you start changing the total amount of military, and obviously, but you're also changing the Normal rythm in how much militants in is being released into your brain and body across the three hundred and sixty five day calendar year.

So well, i'm somebody who readily embrace his supplementation in various forms for things like sleep and focus at sea. When IT comes to melatonin, i'm extremely cautious. And I think it's also one of the few examples where a hormone is available without prescription over the counting.

IT is going to a pharmacy or drugs or order online. This hormonal, which is known to have all these powerful effects. So I get very, very concerned when I hear about people taking military, especially the levels that are present in most supplements.

It's been recognized for a very long time, and in fact, there are now data to support the fact that animals of all kinds, including humans, will seek out mates and engage in mating behavior more frequently during the long days, spring and summer. That's right. In seasonally breeding animals, of course, this is the case.

But in humans as well, there is more seeking out of mates and mating behavior. In longer day times of year. You could imagine at least two mechanisms by which this occurs. The first mechanism, we could easily map to melatonin, and the fact that militant onan is impressive to various aspects of the so called gonads access, which is basically a fancy way of saying that military and inhibits to stop one in estrogen output from the testers and from the coverage.

I just want to remind people that both males and females make testosterone and estrogen, although in different ratios, typically in males versus females, and that both testosterone and estrogen are critical for the desire to mate and forming behavior. There's a badness conception that testosterone is involved in mating behavior and estero s involved in other behaviors. But having enough estrogen is critical for both males and females in order to maintain the desire to mate and indeed the ability to mate.

I discuss this on the episode on optimizing testosterone and estrogen. So if you'd like more details on that, please see that episode of the human man in lab podcast. okay.

So if militant onan is impressive to the so called gonave axis and reduces overall levels of testosterone one and as gen in males and females, and a light inhibits melatonin, then when there's more light than there's less militant a and more hormonal output from the goats. And indeed, that's how the system works. But that's not the entire story.

IT turns out that there is a second so called parallel pathway, meaning a different biological pathway that Operate in parallel to the light suppression of military in pathway that provides a basis for longer days, inspiring more desire to mate and more mating behavior. So if we think of the first pathway involving milestones as sort of a break on these reproductive hormones, the second mechanism is more like an accelerator on those ormonds. And yet, IT still involves light, as i'm about to tell you, in animals such as mice, but also in humans, exposure to light, in particular U.

V, blue lights or short wavelength of light, can trigger increases in testosterone, one in estrogen, and the desire to mate. Now, what's especially important about this accelerator on the desire to mate and mating behavior and hormones is that IT is driven by exposure to light, but IT is not the exposure of light to the eyes. IT turns out that IT is the exposure of your skin to particular wavelengths of light, that is, trigger ing increases in the hormones to stores on an asteroid, leading to increase desire to mate.

As IT turns out, your skin, which most of us just think of as a way to protect the organs of our body or something to hang close on our ornaments on if you're somebody who has earrings and so forth, your skin is actually an enduring organ, meaning IT is a hormone producing and hormone influencing organ. I promise what i'm about to tell you next will forever change the way that you think about your skin and light and the desire to mate, and indeed even mating behavior. I think the results are best understood by simply going through the primary data, meaning the actual research on this topic.

And to do so, i'm gona review a recent paper that was published in the journal cell reports, cell press journal, excEllent journal. This is a paper that came out in twenty twenty one entitled skin exposure to U V B. Light induces a skin, brain, go out access and sexual behavior.

And I want to emphasize that this was a paper that focused on mice in order to address specific mechanisms, because in mice you can, so called knockout particular genes, you can remove particular genes to understand mechanism. You just can't do that in humans in any kind of controlled way, least not at this point in time. And this study also explorer humans and looked at human subjects, both men and women.

The basic finding of this study was that when mice or humans were exposed to U. V B, meaning ultraViolet bluets, a short wavelength of the sort that comes through in sunshine, but is also available through various artificial sources. If they received enough exposure of that light to their skin, there were increases in testosterone that were observed within a very brief period of time, also increases in the hormone estrogen.

And I should point out that the proper ratios of estrogen and testosterone were maintained in both males and females, at least as far these data indicate. And my tended to seek out meeting more and made more. There were also increases in gonads weight, literally increases in testy size and innovation.

An size when mice were exposed to this uvb light passed a certain threshold. Now, as I mentioned before, the study also looked at humans. They did not look at testy size or ovarian size in the human subjects. However, because they are humans, they did address the psychology of these human beings and address whether not they had increases in, for instance, aggressiveness or impassionate feelings, and how the perception of other people changed when they were getting a lot of uvb light exposure to the skin.

So before I get into some of the more important details of the study and how IT was done and how you can leverage this information for yourself, if you desire, I just want to highlight some of the basic findings. Overall, U, V, B exposure increased these so called sexual levels in mice and humans, the sexy hormones. When we say stereo ids, we don't mean anaemic steroids taking exogenous ly.

I think when people hear the words stereo ids, they always think steroid abuse or use rather state hormones such as tester n Anastasia went up when micro humans had a lot of U. V B exposure to their skin. Second of all, U V B light exposure to the skin, enhanced female attractiveness or the perceived attractive ess of females by males, and increase the receptiveness were the desire to mate in both sexes.

U V B light exposure also changed various aspects of female biology related to fertility. In particular, follow growth, follow and ignat's. Ation are well known induces of fertility and of course, correlates with the menstrual cycle in adult humans and is related overall to the propensity to become pregnant.

U, V, B, light exposure enhanced. The maturation of the follow would just meant that more healthy eggs were being produced. These are impressive effects.

First of all, they looked at a large number of variables in the study. And the fact that they looked at mice and humans is terrific. I think that often times we find IT hard to translate data from mice to humans.

So the fact that they looked at both in parallel is wonderful. In the mice and in the humans, they establish a protocol that essentially involved exposing the skin to U. V. Light that was equivalent to about twenty to thirty minutes of midday sun exposure. Now, of course, where you live in the world will dictate whether not that midday sun is very, very bright and intense, or is less bright.

Maybe there's cloud covered sa, but since imagine that most people are interested in ways to increase testosterone and or estrogen in humans and are not so much interested in increasing testosterone in mice, i'm going to just review what they did in the human population of the human subjects. What they did is they had people, first of all, establish a baseline. And the way they establish a baseline was little bit unusual.

But IT will make perfect sense to you. They had people were long sleeves and essentially cover up and avoid sunlight for a few days, so they could measure their baseline hormones in the absence of getting a lot of uvb light exposure from the sun or from other sources. Now, of course, these people had access to artificial lights.

But as i've pointed on this podcast before, it's pretty unusual that you'll get enough U, V, B. Exposure from artificial lights throughout the day. In the morning, you need a lot of U, V, B exposure, or we should be getting a lot of U, V, B exposure to our eyes, into our face, into our skin throughout the day, provided we're not keening sunburn.

This is actually a healthy thing for mood and for energy throughout the day. It's only at night, basically between the hours of about ten P M and four a, that even a tiny bit of uvb exposure from artificial sources can message up in terms of our sleep, in our energy levels and so on. And that's because of the pot effective uvb on suppressing melatonin.

So the point here is that they establish a baseline whereby people were getting some artificial light exposure throughout the day, but they weren't getting outside a lot, they weren't getting a lot of sunlight, and then they had people receive a dose of uvb light exposure that was about twenty to thirty minutes outdoors. They had to wear short sleeves, no hat, no sunglasses. Some people were sleeveless shirts.

They encouraging people to wear shorts. So they were, indeed, we're in clothing. They were not naked and they were wearing clothing that was culturally and situations ally appropriate, at least for the part of the world where this study was done. And they had people do that two or three times a week.

So in terms of a protocol that you might export from this study, basically getting outside for about thirty minutes, two or three times a week in a minimum of clothing, and yet still a wearing enough clothing that is culturally appropriate, they were outside. They weren't sunbathing, flipping over on their back in front. They were just moving about doing things.

They could read, they could talk, they could go about other activities. But they weren't wearing a broad brim hat or hat of any kind, just gain a lot of sun exposure to their skin. They did this for a total of ten to twelve U. V.

B. treatments. So this took several weeks, right? IT took about a month of you think about two or three times for a week for a total tender.

Twelve be treatment. These treatments are are just being outside in the sun. And then they measured hormones, and they measure the psychology of these male and female adult subjects. Let's first look at the psychological changes that these human subjects experienced after getting ten to twelve of these uvb light exposure, outdoor in sunlight type treatments.

They did this by collecting blood samples throughout the study, and they saw significant increases in the hormones beta extradition, which is one of the major forms of echogen progesterone, another important state, ormond, and testosterone, in both men and women. Now an important point is that the testosterone increases were significantly higher in men that happen to originate from countries that had low U. V.

Exposure compared to individuals from countries with high U. V exposure. Now this auto make sense if we understand a little bit about how the skin functions as an underground gan.

Many of you have probably heard of vitamin d three, which is a vitamin that we all make many people supplemented as well. If they need additional vitamin d three, we all require sunlight in order to allow vitamin three to be synthesized and perform its roles in the body. And IT turns out that people who have darker skin actually need more vitamin three and or more sunlight exposure in order to activate that d three pathway.

Then do people with pillar skin. And this should make sense to all of you, given what you now understand about milano sites that sell tide that we discussed earlier, because melanotan des have pigment within them. And if you have darker skin, IT means that you have more melanesians or that you have melanotan des that are more efficiently creating pigment.

And as a consequence, the light that lands on your skin will be absorb by those melanotan des. And less of IT is able to impact the d three pathway. Whereas you have pale skin, more of the light that lands on your skin can trigger the synthesis and assist the actions of vain d three.

Similarly, in this study, they found that people who had pale or skin and door who originated from countries where they had less uvb light exposure across the year had greater, meaning more significant increases in testosterone overall. Then did people who already we're getting a lot of ubb exposure, this LED them to explore so called seasonal changes in testosterone that occurred Normally in the absence of any light exposure treatment. So up until now, i've been talking about the aspects of the study involving people getting outside for about twenty to thirty minutes per day in sunlight in a minimum of clothing.

There was an increase in testosterone on observed in both men and women. The increases in test host were greater for people that had tailor skin, then darker skin. So the data i'm about to describe also come from the same paper, but do not involve twenty to thirty minute daily sun exposure protocols.

It's simply addressing whether not testosterone n levels change as a function of time of year. They measured test astern across the twelve month calendar. This study was done on subjects living in the northern hemisphere for the entire year.

And so in the months of january, february, in march, of course, the length of days is shortest and the lands of nights is longest. And of course, in the spring and summer months, june, july, August, september and so on, the days are much longer and the nights are shorter. And what they observed was very obvious.

They observed that testosterone levels were lowest in the winter months, and we're highest in the months of june, july, August and september. Now these are very important data, at least to mynott. Es are the first data systematically expLoring the levels of sexual hormones in humans as a function of time of year, and thereby as a function of how much sunlight exposure they're getting.

And what's remarkable about these data is that they map very well to the data in mice and the other data in this paper on humans, which illustrate that if you're getting more U V B exposure, your testosterone al levels are higher. This study one a step further and explored whether not the amount of sunlight exposure that one is getting to their skin influences their psychology in terms of whether not they have increased desire to mate and so on. It's well known that sunlight exposure to the eyes can increase mood.

And I talked about this in the podcast episode with my guest, doctor, sammer hadar, who's the director, the chromium logy unit, the national institute of of mental health. And sam's recommendation is that people get as much bright light exposure as they safely can in the morning and throughout the day for sake of boat sleep and energy, but also for enhancing mood and regulating appetite. In this study, IT was found that both males and females had higher levels of romantic passion after getting the U.

V treatment. In fact, some of them reported increases in romantic passion from just one or two of these uv treatments, so they didn't have to go through all ten or twelve in order to get a statistically significant increase in passion. Now when we talk about passion, as the authors of this paper acknowledge, there's really two forms.

There is emotional and sexual. And they passed this pretty finally, I don't want to go into all the details, and we can provide a reference and link to the study if you'd like to look at those details. But what they found was that women receiving this uvb light exposure focus more on increases in physical arousal and sexual passion, whether the men actually scored higher on the cognitive dimensions of passion, such as obsessive thoughts about their partner and so on.

Regardless, both males and females experienced reported an increase in sexual passion and desire to mate. And we now know there were increases in testosterone and estrogen, which of course could be driving the psychological changes, although i'm sure that there was interact in both directions, meaning the hormones no doubt affect psychology, and no doubt the psychology. These changes in passionate feelings no doubt also increased or change the hormonal levels as well.

And I want to reemphasize that there was a component of the study that had no deliberate daylight sunlight exposure for twenty or thirty minutes, but rather just looked at hormonal levels throughout the year and found that the increase in daylife correlated with increases in testosterone and sexual passion. Now my opinion, this is a very note. Thy study, because IT really illustrates that sunlight and daylight can impact the melatonin pathway and thereby take the foot off the break, so to speak, on testosterone estermen in the desire to mate.

IT also emphasizes that sunlight, U V B light, can directly trigger hormonal pathways and desire to mate and mating behavior. Now they study when a step further in defining the precise mechanism by which light can impact all these hormones in this desire to mate. And here, understanding the mechanism is key if you want to export a particular protocol or tool that you might apply.

We talked earlier about how U. V, B. Light exposure to the eyes triggers activation of these particular neurons within the eye, and then with centres deeper in the brain, and eventually the pioneer gland, to suppress the output of milestones, and thereby to allow testosterone in astrogation to exist at higher levels because military and can inhibit to stop on an emergent.

In this study, they were able to very clearly establish that IT is sunlight exposure to our skin that is causing these hormones, increases that they observed in mice and humans. And the way they did that was to use the so called knockout technology, the ability to remove specific genes within specific tissues of the body. And what they found is that U V B light, meaning sunlight exposed, skin up, regulated, meaning increased, the activity of something called p fifty three, which is involved in the maturation of cells and various aspects of cellular function.

And the cells they were focused on, where the catini sites, which you are not familiar with from our earlier discussion about the fact that the epidemic of your skin contains mainly correct noise and more anosike sunlight exposure, increased p fifty three activity in the skin. And p fifty three activity was required for the downstream increases in ovarian size, in testicular size, in testosterone increases, in the estrogen increases, and the various other changes that they observed at the physiological level when animals are humans, were exposed to sunlight. So these data, important, because what they mean is that not only is IT important that we get sunlight exposure early in the day and throughout the day to our eyes at least as much as as safely possible, but that we also need to get U V, B sunlight exposure onto our skin if we want to activate this fifty three pathway in cortner sites.

And the testosterone in asteroid increases that are downstream of that piety three pathway. So even though the gene knock out studies were done on mice, they clearly show that if you remove p fifty three from the skin, that these effects simply do not occur. So in terms of thinking about a protocol to increase the toaster an initial an mood and feelings of passion, the idea is that you would want to get these two to three exposures per week, minimum of twenty to thirty minutes of sunlight exposure on to as much of your body as you can reasonably expose IT to.

And I say reasonably, I mean, of course you have to obey cultural constraints, decency constraints, uh, and of course you have to also obey the fact that sunlight can burn your skin. So many people are probably going to ask, what happens if you wear sunscreen? Well, in theory, because suns screen has U V protection, IT would block some of these effects.

I'm not suggesting that people do away with sung screen entirely. I do hope to do an episode all about sunscreen in the future, because sunscreen is a bit of a controversial topic. Skin cancers are a real thing, and many people are especially prone skin cancer, so you need to take that seriously.

Some people are not very proud of skin cancer, so you can tolerate much more sun exposure. You probably familiar with the simple fact that if you ve gone outside on the beach with friends, some people get burn very easily, others don't. So you really should prioritize the health and the avoidance of sunburn on your skin.

However, these data and other data point to the fact that we should all probably be striving to get more sunlight exposure onto our skin during the winter months and still getting sunlight exposure onto our skin in the summer months, provided we can do that without damaging our skin. Another set of very impressive effects of uvb light, whether that comes from sunlight or from an artificial source, is the effect of U V B light on our tolerance for pain. IT turns out that our tolerance for pain varies across the year and that our pain tolerance is increased in longer day conditions.

And as we saw with the effects of uvb on hormones and mating, again, this is occurring via U. V B exposure to the skin, N. U, V B.

Exposure to the eyes. I want to just described two studies that really capture the essence of these results. I'm going to discuss these kind of a top onto our fashion.

I won't come to IT is quite as much debt as I did the last study, but I will provide links to these studies as well. The first study is entitled the skin exposure to ultraViolet be rapidly activate systemic new endurin and immunosuppressive responses. You might hear that and think, oh, a unus reserve, that's bad.

But basically what they observed is that even one exposure to U V B light change the output of particular hormones and neo chemicals in the body, such as quota catch pen hormones and beta endorphins, which are these endogenous ous opioid. We've all heard of the opioid crisis, which is people getting addicted to opiate that they are taking in drug form pharmacology. But here are referred to endorphins that our body naturally manufacturer and releases in order to counter pain and act as A.

Somewhat about psychological suzor also because, of course, physical pain and emotional pain are intimately linked in the brain and body, what they found was that exposure to U. V B. Light increased the release of these beta endorphins.

IT caused essentially the release of an indigenous pain killer. Now a second study that came out very recently, just this last week. In fact, publishing the journal neuron self press journal, excEllent journal is entitled a visual circuit related to the parao doctor grey area for the anti, not secretive effects of bright light treatment.

I'll translate a little bit of that for you. The parao ducal gray is a region of the middle in that contains a lot of neurons that can release in dargan, ous, oppos, things like beta and kaolin, things like n caffe, things like new ops. These are all names of chemicals that your body can manufacture the act, as in doggy ous pain killers, and increase your tolerance for pain.

They actually make you feel less pain overall by shutting down some of the neurons that perceive pain or by reducing their activity. Not to a dangerous level, right? They're not going to block the pain response so that you burn yourself unnecessarily or harm yourself unnecessarily, but they act as a bit of a pain killer from the inside.

If you heard the word anti, no secretive, no action is basically the perception or the way in which neurons respond to painful stimuli. So you can think of no secretive events in your nervous system as painful events. And they are using abroad brush.

I realized that the experts in pain e will say, oh, it's not a really a pain circuit. It's that, it's that. But for sake of today's discussion, it's fair to say that no secretion is the perception of pain.

So if this title is a visual circuit related to the parochial cal gray, which is this area that releases these indulges opioid for the anti nosis cept of the anti pain effects of bright light treatment, the key finding of this study is that IT is light landing on the eyes and captured by the specific cells I was talking about earlier, those intrinsic photosensitive melon ops and gangling cells as the long name for them. But these particular s in your eye and in my eye, incidentally, that communicate with particular brain areas. These brain areas have names, if you want to know them, for you official autos, or for you ultra curious folks they have named, like the venture al latini, I ate nucleus and the intergenerational afi.

The names don't matter. The point is that light landing on the eyes is captured by these melon open cells. They absorb that light, trans like that light, into electrical signals that are handed off to areas of the brain, such as the venture generate.

And then the venture genetic late communicates with this paradox reductive grey area to evoke the release of these endogenous opiates that suit you and lead to less perception of pain. This is a really important study because it's long been known that in longer days or in bright light environments, we tolerate emotional and physical pain Better. Previous studies have shown that IT is lightning ding on our skin that mediates that effect, but only in part IT could explain the entire effect.

This very recent study indicates that is also light arriving at the eyes, and in this case, again, U V, B light, ultraViolet e light of the store that comes from sunlight that is triggered these anti pain or pain relieving pathways. So once again, we have two parallel pathways. This is a theme you're going to hear over and over and over again, not just in this episode, but in all episodes.

The huberman and lab podcast, because this is the way that your brain and body are built, nature rarely relies on one mechanism in order to create an important phenomenon, and pain relief is an important phenomenon, so we now have at least two examples of the potent effects of U, V, B light exposure to the skin, into the eyes. One involving activation of testosterone and estrogen pathways as IT relates to mating, in another that relates to reducing the total amount of pain that we experience in response to any painful stimulus. For those of you, they are thinking tools and protocols.

If you're somebody who's experiencing chona pain, provided you can do IT safely, try to get some U. V. B exposure, ideally from sunlight. I think the twenty or thirty minute protocol, two or three times per week, is an excEllent one. Seems like a fairly low dose of U V B.

Light exposure is hard to imagine, getting much damage to the skin, of course, of you a very sensitive skin, or if you live in an area of the world that is very, very brighten, has intense sunlight particular times of year, you will want to be cautious, heed the warnings and considerations about sun stream that I talk about earlier, or about wearing a hat. But the point is very clear. Most of us should be getting more uvb exposure from sunlight.

I can already hear the screams within the comments, or the rather the questions within the comments saying, well, what if I live in a part of the world where I don't get much U V B exposure? And I want to emphasize something that i've also emphasize in the many discussions on this podcast related to sleep in circling rhymes and alertness, which is even on a cloud cover day, you are going to get far more light energy photons through cloud cover. Then you are going to get from an indoor light source and artificial light source.

I can't emphasize this enough. If you look outside in the morning and you see some sunlight, if you see some sunlight throughout the day, you would do yourself a great favour to try and chase some of that sunlight and get into that sunlight, to expose your eyes in your skin to that sunlight as much as you safely can. When I say as much as you safely can never ever look at any light, artificial sunlight or otherwise that so bright that it's painful to look at, it's fine to get that light arriving on your eyes.

Indirectly, it's find where eyeglasses or contact lens is. In fact, if you think about the biology of the eye and the way that those lenders worked, that you will just serve to focus that lied on to the very cells that you want those light beams to be delivered to, whether sunglasses that are highly reflective or trying to get your sunlight exposure through a windshield of a car or through a window, simply won't work, i'm sorry to tell you. But most windows are designed to filter out the uvb light.

And if you're somebody who's really keen on blue blockers and you wearing your blue lockers all day, well, don't wear them outside. And in fact, you're probably doing yourself a disservice by wearing them in the morning and in the daytime. There are certainly as a place for blue blockers in the evening and nigh time if you're having issues with falling and staying asleep.

But if you think about IT blue blockers, what they're really doing is blocking the short wave line to uvb wavelength light that you so desperately need to arrive at your retina, and of course, also onto your skin in order to get these powerful biological effects on hormones and on pain reduction. And in terms of skin exposure, these data also might make you think a little bit about whether or not you should wear shorts, sleeves or long sleeves, whether not you want to wear shorts or skirt or pants. It's all going to depend on the context of your life and the social and other variables that are important.

Of course, I don't know each and every one of your circumstances, so I can tell you to do x or y or z, nor would I. But you might take into consideration that IT is the total amount of skin exposure that is going to allow you to capture more or fewer photons depending on brinson. If you're completely closed to and clothing and you're just, you know, exposed in the hands, necked and face such as I am now or whether not you're outside in shorts and A T shirt, you're going to get very, very different patterns of biological signaling activation in those two circumstances.

Many of you, i'm guessing, are wondering whether or not you should seek out uvb exposure throughout the entire year only in the summer months. And that sort of going to depend on whether not you experience depression in the winter months. So called seasonal effective disorder.

Some people have mild, some people have severe forms of seasonal factor disorder. Some people love the fall in winter, in the shorter days. They love bungling up.

They love the leaves, they love the snow, they love the cold, and they don't experience. So psychological laws, so IT varies tremendously. And there are genetic differences and birth place origin differences that relate all this. But really, IT has to be considered on a case by case basis, I personally believe.

And this was reinforced by the director of the china biology unit at the national institute of mental health service, itar, that we would all do well to get more uvb exposure from sunlight throughout the entire year, provided we aren't burning our scanner, damaging our eyes in some way. In addition to that, during the winter months, if you do experience some drop in energy years, increase in depression or psychological laws, IT can be very beneficial to access a sad lamp. Or if you don't want to buy a sad lamp, because often times they can be very expensive, you might do well to simply get A L, D lighting panel.

I've described one before, and I want to emphasize that I have no affiliation whatsoever to these commercial sources. But i've described one before, and i'll describe IT again. And we can provide a link to a couple examples of these.

And the show te, the show note captions, excuse me, says a nine hundred and thirty to thousand locks. L U, X light source is designed for drawing. It's lia.

Drawing box is a thin panels about the size of a laptop, very inexpensive compared to the typical sad lab. I actually have one of my position on my desk all day long. I also have a ough skylights ove my desk.

I'm fairly sensitive to the effects of light. So in longer days I feel much Better than I do in shorter days. I've never suffered from fob l on seasonal effect or disorder, but I keep that light source on throughout the day, throughout the year.

But I also make IT a point to get outside and get sunlight early in the morning and several times throughout the day. And if it's pretty clearly overcast outside or there just doesn't seem to be a lot of sunlight coming through those clouds, I will try to look at that light source a little bit more each day in order to trigger these mechanisms. Now some people may desire to get U, V, B exposure to their skin, and they wanted do that sources other than sunlight.

And there is a little bit more complicated. There are course canning solons, which basically are beds of uvb light. That's really all they are never been to one.

I know people do frequently them in certain parts of the world. They are, of course, people are covering their eyes. They are only getting U V B exposure to the skin typically because the U V B exposure or intensities rather tend to be very, very high.

And so you can actually damage your eyes if you're looking at a very, very bright artificial uvb source up close. So you really have to explore these options for yourself. Sunlight, of course, being the original and still the best way to get U, V B exposure.

So without knowing your particular circumstances, finances, genetics or place of virgin said, I can't know whether not you need to use artificial sources. You're going to have engage that. Meanwhile, getting outside, looking at in getting some exposure of U V, B onto your skin is going to beneficial for the vast majority of people out there.

And in fact, it's even going to beneficial for people that are blinded, people that are blind, provided they still have eyes, often maintain these melon ops in cells. So even if your low vision or no vision, getting uvb exposure to your eyes can be very beneficial for sake of mood, hormonal pathways, pain reduction and so forth. A cautionary note, people who have retinas, pigmentosa macular generation or glow coma, as well as people who are especially prone to skin cancers, should definitely consult with your ethnologist and dermatologist before you start increasing the total amount of U, V, B.

Exposure that you're getting from any source, sunlight or otherwise. There are additional very interesting empowering effects of U V B. Light, in particular on immunity unction. All the organs of our body are inside our skin. And so information about external conditions, meaning the environment that were in need to be communicated to the various organs of our body, some of them have more direct access to whats going on outside.

So for instance, the cells in your brain that resides right over the room of your mouth, your yahoo mst, that control hormonal output and the control the biological functions that we call circadian functions, the one that change every twenty four hours. Well, those are just one or two connections, meaning synapses away from those cells in your eye that perceive you be U. V.

B. light. Excuse me, other organs of your body, such as your spleen, which is involved in the creation of molecules and mcelwain combat infection. Well, those are a long ways away from those cells in your own. In fact, there are a long ways away from your skin.

There are beautiful studies showing that if we get more U, V, B exposure from sunlight or from appropriate artificial sources, that spring and immune function are enhanced. And there's a very logical well estaban circuit as to how that happens. Your brain actually connects to your spin.

Now it's not the case. You can simply think OK spin, turn on released killer cells, go out in combat infection. However, uvb light arriving on the eyes is known to trigger activation of the neurons within the so called sympathetic nervous system. These neurons are part of the larger thing that we call the automatic nervous system, meaning it's below or not accessible by conscious control. The thing that controls your heartbeat, controls your breathing, and that also activites are flips on the switch of your immune system.

When we get a lot of U, V B light in our eyes, or I should say, sufficient U V B light in our eyes, a particular channel, a particular set of connections within the sympathetic nova system is activated, and our spring deploys immune cells and molecules that scavenge for and combat infection. So if you've noticed that you get fewer colds and flus and other forms of illness in the summer months, part of that could be because of the increase in temperature in your environment, because typically longer days are associated with more warmth in your environment as opposed to winter days, which are short. When he tends to be called her out, well, that's true, but it's also the case.

The people around you have fewer cause influence, and that you will get infected with your calls, influence and other infections. Because if those infections, whether not their bacteria or viral, arrive in your body, right, if you inhale them or they get in your mouth or on your skin, your spain meets those infections with a greater output. In other words, the soldiers of the umi system, the chemicals in cell types of union system that combat infection, are in a more ready deployed stance, if you will.

If you want to know more about the immune system and immune function, I didn't entire epo de about the immune system and the brain. And you can find that a huberman lab dot com, we talk about side to kins. We talk about killer cells, b cells, t cells.

That said, are a lot of detail there. So we often think about the summer months, and the spring months says fewer infections floating around. But in fact, there aren't fewer infections floating around.

We are simply Better at combating those infections and therefore, there's less infection floating around. So we are still confronted with a lot of infections. We're just able to combat them Better. What does this mean in terms of a tool?

What that means is that during the winter months, we should be especially conscious of accessing U V, B light to enhance our spring function, to make sure that our sympathetic nervous system is activated to a sufficient level to keep our immune system deploying all those killer t cells and b cells and sidelines so that when we encounter the infections, as we inevitably will, right, we're constantly being bombarded with potential infections, that we can comment those infections well and is just a brief aside. But I should mention a brief aside that's related to tens of thousands of quality studies. IT is well known that wounds healing is faster when we are getting sufficient uvb exposure, typically that's associated with the longer days of spring, summer.

IT is known that turn noa of hair cells, the very cells that give rise to hair cells are called stem cells. The'd live in little so called niches in our skin with these hair stem cells. And your hair grows faster in longer days.

That, too, is triggered by U. V, B. Exposure, not just to the skin, but to the eyes. That's right. There was a study publish in the proceedings of the national academy of sciences couple of years ago that showed that the exposure of those melon ops and gangland cells in your eyes is absolutely critical for trigger ing. The turn cover of stem cells in both the skin and hair, and also IT turns out in nails.

So if you've noticed that your skin, your hair and your nails look Better and turn over more, meaning grow faster in longer days, that is not a coincidence. That is not just your perception. In fact, hair grows more, skin turns over more, meaning it's going to look more youthful, you're gna centuries, remove older skin cells, were replaced them with news cells.

And all the renewing cells and tissues of our body are going to proliferate or going to recreate themselves more when we are getting sufficient U, V, B. Light to our eyes and also to our skin. And so, well, some of you may think of light therapies, such as red light therapy or uvb therapies as kind of new ag.

Or just biohacking. Again, a phrase. I don't particularly like this notion of biohacking, because IT implies using one thing for a purpose that I was never intended to have. Well, IT turns out that U. V, B exposure and red lights well soon see is a very poor form of increasing things like wounds healing and skin health for very logical mechanistically about reasons. So well, I can't account for everything that's being promoted out there in terms of this light source will help your skin look more youthful or will help heal your scars. The mechanistic basis for light having those effects makes total sense.

But what you should consider, however, is that if the particularly light therapy that you're considering involves very local application rather than illuminating broad swath of skin, and if IT has no involvement with the eyes, meaning there no delivery of U V B or red light or the other light therapy to the eyes, it's probably not going to be as put into a treatment as would a more systemic activation of larger areas of skin in the eyes. Now, again, a cautionary note. I don't want people taking technologies that were designed for local application and beaming those into the eyes that could be very, very bad and damaging to your retina and other tissues.

Certainly, when when you taking bright light of very high intensity of any kind and getting caviar about that, typically the local illumination of, say, a wound or particular patch of iconic or some other form of skin treatment involves very high intensity light. And if the intensity is too high, you can actually damage that skin. And so as we will talk about in a few moments, most of those therapies for modifying skin involved actually burning off a small, very thin layer at the top of the epidermis in efforts to trigger the renewal or the activation of stem cells that will replicate that with new cells. So there is a fine line to be had between light therapies that are very localized and intense, which are designed to damage skin and cause reactivation of new stem cells, but not tair cells or skin cells.

That said, a versus systemic activation across broad swath of skin in the eyes really have to consider this on a case by case basis, but at least for now, just consider that increases in hormones, reduction in pain by way of increases in and caffeine and other indigenous opioids, improving immune status by activating the spin and so on and so on, really are all the downstream consequence of illuminating large swath of skin and making sure that those neurons in within the eye get their adequate U, V, B exposure or other light wave light exposure, not simply beaming a particular wavelength of light at a partial location on the body and hoping that that particular illumination at a particular location on the body is going to somehow changed the biology at that location. Our biologists just really doesn't work that way. It's possible.

But in general, systemic effects through broad scale, lumination and illumination to the eye, combined with local treatments, are very likely to be the ones that have the most success. Now i'd like to shift our attention to the effects of light on mood. More specifically, we talked about this in terms of seasonal effective disorder, but many of us don't suffer from seasonal effect of disorder.

So i'd like to drill little deeper into how light impacts mood. And here I want to again periphrase the statement of doctor samer guitar at the national institute of mental health. I should mentioned the director of the chronic bio g unit at the national institute of mental health, and perhaps one of the top one to two to three world experts in how light can impact mood, appetite, circuiting rhymes and so forth.

Samer stated on the podcast. He said in various other venues as well that getting as much uvb light in our eyes and on our skin in the early day throughout today as as safely possible is going to be beneficial for mood. There is also another time of day, or rather, I should say, a time of night in which uvb can be leveraged in order to improve mood.

But it's actually the inverse of everything we've been talking about up until now. We have a particular neural circuit that originates with those melon open cells in our eye that bypass all the areas of the brain associated with circadian in clocks. So everything related to sleep and wakefulness, that's specifically dedicated to the pathways involving the release of molecules like dopy, the neuro module that associated with motivation, with feeling good, with feeling like there's possibility in the world and so on and so forth, and other molecules as well, including serotonin and some of those indigenous opioids that we talked about before.

That particular pathway involves a brain structure called the perhaps ua nucleus. The perhaps ua nucleus gets input from the cells in the eye that respond to U, V, B, light, and Frankly, to bright light of other wavelength as well. Because, as you recall, if the light is bright enough, even if it's not U, V, or blue light, IT can activate those cells in the eye.

Those cells in the eye communicate to the Perry haben al nucleus. And as IT turns out, if this pathway is activated at the wrong time of each twenty four hour cycle, mood gets worse, doping output gets worse. Molecules that are there specifically to make us feel good actually are reduced in their output.

So while U V B exposure in the morning and throughout the day is going to be very important for IT, elevating and maintaining elevated mood, avoiding U V B light at night is actually away in which we can prevent activation of this eye peri habu lar pathway that can actually turn on depression to be very directed. To think about this, avoid exposure to uvb light from artificial sources between the hours of ten P M and four A M. And if you're somebody who suffers from low mood and overall has a kind of mild depression or even severe depression, of course, please see a psychotic st, see a train.

Psychologists get that treated. But you would do especially well to avoid U V, B. Exposure from artificial sources, not just from ten P M to four I M, but really be careful about getting too much exposure to uvb even in the late evening.

So eight pm, perhaps to four A M. I can't emphasize this enough that if you view U V B, like you activate those neurons in your eye very potentially. And if those cells communicate to the perun, a nucleus, which they do, you will chunky or reduce the amount of dopamine that you release.

So if you want to keep your mood elevated, get a lot of light, you will be light throughout the day and at night. Really be cautious about getting uvb exposure from artificial al sources. Now let's say you're somebody who has no issues with mood.

You're just the happiest person all year long or maybe you just have subtle variations in your mood. You feel great about that. Turns out that you still want to be very careful about light exposure between the hours of ten P M or so.

And for I M in fact, even during sleep, there's a recent study that just came out in the proceeds of the national academy of sciences, and it's entitled light exposure during sleep in paris. Cardio meta lic function this is a very interesting study where they took human subjects, Young adults, and having them sleep in rooms that had different lighting conditions, either dim light or slightly bright light. Now many people can't fall asleep in brightly lit rooms, so they acknowledge this.

These were not very brightly with rooms. These were rooms that had just a little bit of overhead room lighting, a hundred locks, which is not very bright at all, or they had them sleep in a room that had very dim light, which is less than three locks. If you want to get a sense of how bright three locks is versus one hundred looks, I would encourage you to download the free APP light meter.

I have no relationship to the APP. It's a prety cool lap. However, I used IT for a long time where you can basically point your phone, add a particular light source, sun or otherwise, and you just press the button and will give you an approximate read out of locks, which is the light intensity that the phone happens to be staring out at at that location.

It's not exact, but it's a pretty good back at the enable measure of light intensity. So these subjects were either sleeping in a very dim room, three looks is very, very dim, or a somewhat dim room, one hundred looks. In the study, they measured things like melatonin levels.

They looked at heart rate, they looked at measures of insulin and glucose management. Now in previous episodes, i've talked about how glue hose blood sugar is regulated by insulin because you don't want your goods SE levels to be too high hybrid glimmer or too low hypothesize. And the hormone insulin is involved in the westering and shuttle glucose in the bloodstream.

Basically, how well you manage glue coasts in the bloodstream can be indirectly measured by your insulin levels and is well known that sleep deprivation can. Rupp glucose regulation by insulin. However, in this study subjects, we're sleeping the whole night through IT.

Just so happens that some of the subjects were slept, this very dimly lit room, three locks, and other subjects were sleeping in a somewhat dim room, one hundred locks. What's incredible about this study is that both rooms were sufficiently deemed that military levels were not altered. In either case, this is really key.

It's not as if one group experience a lot of bright light through their eyelids and others did not. Military on levels were not disrupted. And given how potent tly like an inhibit military on this speaks to the fact that this very dim condition of three locks and the somewhat dim condition of one hundred locks was not actually perceived by the subjects, nor was a disrupting these hormonal pathways.

They also looked at blue coast responses. They had people essentially take a fasting blue coast test in different conditions. I want to go into all the details, but here's what they found in healthy adults, even just one night of sleeping in a moderately let environment is hundred lux environment caused changes.

Increases in nighttime heart rate, which means that the sympathetic local system was overly active as compared to people that slept in a completely dark or in a very, very dimly room, decreases in heart rate variability. And here I should point out that heart rate variability, or H R V, is a good thing. We want heart rate variability.

So saw increases in heart rate decreases and heart rate variability, and increases in next morning insulin resistance, which is an indication that glucose management is suffering. So this is powerful. The results of this study essentially indicate that even just one night of sleeping the whole night through in a dimly let environment is disrupting the way that our automatic error system is functioning.

Altering so called atomic tone, making us less relaxed, is probably the best way to describe IT, even though we are sleep disrupting the way that our cardio meta lic function Operates such that we have lower Harry variability and increased insuing resistance. This is not a good thing for any of us to experience so well. We've mainly been talking about the positive effects of uvb light and other forms of light. Now we have two examples won from the work of haiti and colleagues showing that U V B. Exposure via the Perry humana can diminish the output of dopamine and other molecules that make us feel good if that uv b exposures in the middle of the night or late evening.

And now we have yet another study performed, in this case in humans, indicating that even if we fall asleep and sleep the whole night through, if the room that we're sleeping in has too many locks, too much light energy, that light energy is no doubt going through the islands, which IT can activating the particular cells in the eye that trigger an increase in sympathetic nervous system activation and disrupting our metabolism. And this study rests on a number of other recent studies published in cell, which is a superb journal and other journal, showing that during the course of a healthy, deep nights sleep, our body actually transitions through various forms of media lic function. We actually experience key tosa like states.

We experience glucose o genesis. We experience different forms of metabolic associated with different stages of sleep, not something that we're going into in depth in this podcast. We will in a future podcast. What this study shows is that light exposure, even in sleep, is disrupting our autonomic, in this case, the sympathetic ARM of the autonomic nervous system, in ways that are disrupting the tables.

M probably in sleep, but certainly outside of sleep, that we wake up and have our first meal of the day, or even if you you're internet fasting, you eat that first meal of the day. If your sleep is taking place in an environment that's overly illuminated, well, that's disrupting your cardiac function and your metabolism. I've been talking a lot about U, V, B light, which is a short wave, light, light.

So U, V, light, blue light, maybe even in some blue Green light that's going to a short wave light, light. Now I D like to shift our attention to the other end of the spectrometer ing the light to talk about red light and infrared light, which is a long wavelength light, many so called low level light therapies, the iconium is L L L T. Low level light therapies involve the use of red light and informed light.

Sometimes low level light therapies involve the use of U, V B. But more often than not, these days, when we hear L, L, L T. Low level light therapy, it's referring to red light and near infrared light therapies.

Low level light serapes have been shown to be effective for a huge number of biological phenomenon in medical treatments. I can't summarize all of those now. IT would take me many, many hours. Would be an effective episode for curing insomnia, but IT wouldn't inform you properly about the use of light for your health. Rather, i'd like to just emphasize some of the top on tour of those studies and point out that, for instance, low level light therapy with infant light has been shown to be effective for the treatment of acne and other sorts of skin lesions. Been some really nice studies actually, where they use subjects as their own internal control.

So people who believe they are not agree to have half of their face illuminated with red light or near and for head light, and the other half of their face service is a control, and to do that for several weeks at a time, and you can see pretty impressive reductions in skin lesions, reductions in scars from acne and reduction in acne lesions themselves. S meaning the accumulation of new acne is with low level light therapy using red light and input red light sometimes, however, there is a resistance of that iconic to the low level light therapy, such that people will get an initial improvement and then it'll go away despite continuing. The treatment.

So you're probably asking, or at least you should be asking, how is IT that shining red light on our skin can impact things like aconites wound healing? Etta, well, to understand that, we have to think back to the beginning of the episode where I described how long wavelength light, such as red light and near room for red light, which is even longer than red light, can pass through certain surfaces, including our skin. So our skin has an epidemics, which is on the outside, and the dorma, which is in the deeper layers.

Red light and infant light can pass down into the deeper layers of our skin, where you can change the metabolite function of particular cells. So let just take acting as an example. Within the dark is the deep layers of our skin.

We have what are called sebastian ous gLance that actually make the oil that is present in our skin. Those sebaceous st. Glans are often nearby airfo's ics. So if you've ever had a infected hafod, that's not a coincident that have focus, tend to get infected.

Part of IT is because there's actually a portal down and around the hair folio, but the subacid ious plan is where the oil is created that is going to give rise to differences, act illusions also in the dermis, in the deep layers of the skin or the milano sites. They're not just in the epidemic, also in the deeper layers of the skin. And you have the stem cells that give rise to additional skin cells.

If the top layers of the epidermis mage, those stem cells can become activated. And you also have the stem cells that give rise to hear folks. So by shining red light or near infor red light on a localized patch of skin, provided that red light is not of such high intensity that IT burns the skin, but is of sufficient intensity that provides just a little bit of damage to the upper layers of the skin, the epidermis.

And that IT triggers certain biological pathways within the cells of the subacute ous gland and the stem cells within the hair cell niche and the stem cells in skin, what happens is the top layers of the skin are basically turned off by a very low level of burn, and or the cells in the deeper layer start to turn out new cells, which go and rescue the lesion, essentially clear out the lesion and replace that region with healthy skin cells. This does work in the context of wound healing, getting scars to disappear. IT also works to remove certain patches of pigmentation.

There are sometimes cases where people will get a red blocks inss um due to certain skin conditions or some darker pigmentation that they won't remove her, that they need removed because it's a potential skin cancer threat. Now how is red light actually doing IT within the cells of the subacute gan and the stem cells? That said, well, long wavelength light can actually get deep into the skin.

I mentioned that before. We can also get into individual cells and can access the so called organic, which I described at the beginning of the episode. Particular, they can access the Mandara, which are responsible for producing ATP.

Now, the simple way to think about this, for sake of this discussion, is that as sales age, and in particular in very metabolically active cells, they accumulate what are called R O S S reactive oxygen species. In as reactive oxygen species go up, atp energy production in the cells tends to go down. It's a general statement, but it's a general statement that in most cases is true.

There are some minor exceptions that don't concern us that have to do with cell types different than the ones i'm talking about now. So the way to think about this is that red light passes into the deeper layers of the skin, activates meter contra, which increases and directly or indirectly reduces these reactive oxygen species. These reactive oxygen species are not good.

We don't want them. They cause seller damage, seller death, and for the most parches, inhibit the way that ourselves work. So if you heard of red light or curing for red light therapies, design to heal skin or improve skin quality, or remove legions, or get rid of scars or unwanted pigmentation, that is not super science, that is not wu science, that is grounded in the very biology of how light interacts with meta contra and reactive oxygen species.

Some of you may also find an interesting to note that some of the queen bed treatments for acne, for instance, like retinal acid written a, is actually a derivative of vitamin, and the pathway involving retina, ic acid and vitamin, believe IT or not, is very similar to the natural biological pathway by which photo pignone in the eye convert light information to biological changes within those cells. So the key point here is that light is activating particular pathways and else that can either drive death of cells or can make those cells essentially Younger by increasing atp by way of improving medical dro function. And in recent years, there have been some just beautiful examples that exists not only in the realm of skin biology, but in the realm of neurobiology, whereby red light and near room for red light can actually be used to enhance the function of the cells that, for instance, allow us to see Better, and indeed, cells that allow us to think Better.

So now i'd like to review those data because not only are they interesting in their own right, but they also point to some very interesting and powerful application of low cost is zero cost tools that we can use to improve our vision. If you are somebody who's interested in the use of red light or near in for red light, so called llt low level light therapies for treatment of germanic ologies issues, so anything related to skin, I will include a link to a excEllent set of reviews. The first one is light meeting dialed in dramatic logy.

A systematic review of renommist control trials. That one includes review of a very large number of studies came out just a few years ago in twenty eighteen, and I think is very clear and cleanly laid out for anyone to access. You can see the degree of effects of red light, for instance, on treatment of acting or scoring, IT, said a, and i'll also provide a link to another review, which is low level light therapy in skin stimulating, healing and restoring.

So for for those who that are interested, again, mental logic issues and the kind of restoring youthfulness and the kind of, uh, general themes of of anti aging and longevity and how red light therapy can be used for that, I will engage you to take a look at those reviews. What you're going to find is that rarely, if ever, is there a study looking at whole body red light illumination for the sake of treating and improving skin. And I mentioned this because I get a lot of questions about inf red sona.

And global illumination with red lights will talk more about cases where a global illumination of your whole body, your, your whole face with red lights might be useful. But in terms of infrared sauna, i've mentioned on this podcast before, and I will certainly go deeper on this in an upcoming episode, all about the use of heat and temperature for augmenting our biology. But in general, infrared saunas don't get hot enough temperature wise in order to trigger some of the important effects on growth hormones and heats shock proteins and some of the other things that sona has been shown to be excEllent for.

That's a general statement. I realized there are awesome impact on us that do get hot enough. There are a very few data on the use of whole body illumination with infrared saunas.

They really point to any specific mechanistically supported effects, almost all the positive effects that are gonna a red light in the level light therapies, certain ly, the ones discuss in the reviews that I just mention are going to be the consequence of very directed illumination of particular patches of skin that are seeking repair that people are seeking the repair of. So again, I don't want to disparage infra sona, but in general, they don't get hot enough to trigger most of the positive effects that sona have been demonstrated to have. And it's unclear at all as to whether not they can enhance skin quality, youthful ness, restore uh you know top players of skin that are damaged, uh, repair acne, etcetera.

So more on heat sona and infrared saunas and their comparison in an upcoming episode. So let's talk about a clear set of examples where red light and near and for red light have been shown to have positive effects on our health. And these are the data that I referred to at the beginning of the episode from dr.

点， glen Jeffery at university college london, who again is a long standing member of the neuroscience community working on visual neuroscience, and who over the last decade or so has really emphasized the exploration of red light and near and for red light for restoration of neuronal function as we age. This is absolutely critical. We know that we don't accumulate many new brain cells as we get older.

And in some areas of our nervous system, such as our neural retina, which is the part of our I that's responsible for translating light information to electrical signals, so that we can see we don't get any new cells after the time in which we are born. So the ability to keep our neurons healthy is extremely important for our visual system, extremely important for our hip campus scene, the brain involved in memory. And should just mention that even if people don't get alzheimer's, there always going to be some degree of age related dementia.

Sadly, nobody is as cognitive ly sharp in the years before they die as they are twenty years before. That is just never the case. We're all getting worse at thinking, feeling, perceiving at sada.

The question is how quickly we are getting worse. So any mechanism by which we can preserve or reverse neuro onal function turns out to be immensely beneficial. The jeffrey lab has published two studies in recent years on humans that looked directly, no one intended at how red light and nearing for red light can improve visual function.

I'm going to describe the parameters of those studies, and then i'm going to describe what they found. exactly. The mechanistic motivation for these studies, again, traces back to the effect of light on meda country.

So to go a little bit deeper into that mechanism just briefly, so that you can frame any potential protocol that you would develop when light arrives on cells, including neurons, that light can penetrate into the cells of its of the appropriate wavelength. Red light can do that, can get into cells. I can access the meter contact IT, can increase ATP.

In general, any time atp is doing its thing to increase energy and cells is involving this thing called side chrome sea, which is an oxy dates. Anytime you hear S A S E and biology, it's going to be an enzi. It's involved in some process of degrading a molecule and creating another molecule typically.

So atp inside chrome sea is going to give you A, T, P. Now that's a great thing. But IT creates a buy product.

IT breaks things down such you get these R O S S, these reactive oxygen species. And those reactive oxygen species, for those of you that want to know, are involved in things like a redox signaling. And reactive oxygen species actually change which genes are made in a cell.

So the goal of any treatment to keep neons or other cells youthful and functioning well and to prevent or reverse aging is going to be to increase atp and to reduce reactive oxygen species. And in doing so, to disrupt some of the Normal pathways associated with aging, the Jeffery lab approached these studies with that understanding of how ma contra in active oxygen species in atp work. And what they did was exquisitely simple to the point of being elegant.

And what they found was really, really exciting. What they did is they had people, subjects that were either Younger, so in their twenty years or forty years old or older, view red light of about six hundred and seventy nanometers. Six hundred and seven nanometers would appear red to you and me.

They, they had them do that, excuse me, at a distance that was safe, further eyes. So at about a foot away. Now, a foot away from a very intense red light could actually be damaging to the eyes.

So they had them do this about a foot away from a red light that was a low enough intensity that did not damage the eyes. And they had them do that anywhere from two to three minutes per day. And in one study, they had them do that for a long period of time of about twelve weeks. And in the other study, they had them do that just for a couple of weeks.

What's remarkable is that when you collapse the results across these two studies, what they found is that when looking at these subjects ranging from twenty eight years old to about seventy two years old, the major findings were that in individuals forty years old or older, so in the forty to seventy two year old bracket, but not in the subjects Younger than forty years old, they saw an improvement in visual function. That improving in visual function was an improvement in visual acuity, meaning the ability to resolve fine detail and using a particular measure of visual function, which is called the train exam T R I T A N training exam, which specifically addresses the function of the so called short wave, else comes the ones that respond a Green and blue light. They saw a twenty two percent improvement in visual acuity, which in the landscape of visual testing is an extremely exciting result.

okay. So I think in most studies of improvements of vision, you'd be very excited to see the improvement of five person or ten percent. So a twenty two percent improvement in visual acuity, even though it's in this very specific form of visual testing, this thread exam or this threatened score.

Well, that turns out to be very significant and translates to the real world in an important way. In particular, as we age, we tend to lose certain neurons within our retna, but we don't tend to lose coes. We tend to lose rods. We tend to lose other cells within the retina, including the cells that connect the eye to the brain.

The so called gangling cells comes, for whatever reason, are pretty resilient to age related laws, however, because rodd and comes both are not just among the most metals icc active cells in your entire body, but the most metabolite active cells in your entire body. That's right, your rose and coins of the cells that demand and that use the most energy of all the cells in your body, not your skin cells, not your skin, is not your stomach s. Cells, even if you talk a lot, not the cells are responsible for moving your mouth IT is the rods and cones of your neural retina that are responsible for using the most amount of atp and energy in your entire body.

And because of that, those cells tend to accumulate a lot of reactive oxygen species as we age. Red light of the sort used in these studies was able to reduce the amount of reactive oxygen species in the Robin cones and to rescue the function of this particular contact. The short wavelength minium wavelengths, which, if you think about the study, is a little bit surprising, because IT was red light and near him for red light, not short wavelength, that was used in order to create this improvement in cellular function.

But if you step back a little bit further, IT makes perfect sense because there's nothing specific about the red light in the sense that it's not that IT gets delivered only to red coes. That red light and near room for red light is being absorb by all the photo sectors within the eye, the rods and the blue cones and the Green count. And the red count is just that the red cones absorb that light best.

So the important take away here is that viewing red light in your room for red light at a distance at which is is safe for just a couple of minutes each day, allowed a reversal of the aging process of these neurons, which some people have heard me say before. And i'll just say that again, the retina, including your photo receptors, are not just connected to your brain. They are not just near your brain.

They are actual central neuro system tissue. They are the only two pieces of your brain, many no redness of the only two pieces of your brain that resides outside your scholar, at least outside the crane, evolve. So here we're seeing a reversal of the aging process in neurons by shining red light on those neurons.

Now, of course, the jeffrey lab is primarily interested in vision. And humans are most dependent on vision as a sense, to navigate the world and survive. So this is really wonderful. Here we're looking at a therapy that can reverse age related vision loss, at least in some individuals.

But as you can imagine, the study was also done on the cells because they resided outside the skull, and you can shine light directly on them, right? I'm sure that there are many people out there who are interested in how they can improve the function, say, of the neurons in their brain responsible for memory. And in a few minutes, i'll described the non invasive applications of light to try to restore the function of those cells as well.

So a little bit more about the studies from the Jeffery lab. One of the things that they observed was a reduction in so called rosen D R U S E N ruin our little fatty deposits, low collect al deposits that accumulate in the eye. E as we age.

We've all heard about cholesterol within our veins and arteries, and how that can clog our veins and arteries, and how, of course, closing veins and arteries is not a good thing. Well, our neural retta up being so mediocre, active requires a lot of blood flow, is heavily vaio ized. And drews in are a special form of classical that accumulate in the eye.

As IT turns out, these red light and near room for red light therapies explored by the jeffrey lab were able to actually reduce or reverse some of the accumulation of Jason. And so in addition to reducing reactive oxygen species, the idea in my now is that red light may actually reduce cholesterol deposit and reactive oxygen species in order to improve internal function. So what should you and I do with these results? Or should we do anything with these results? Well, first of all, I want IT emphasize that even though these studies are very exciting, they are fairly recent.

And so more data, as always, are needed. There's some additional features of these studies that I think are also important to consider. First of all, the exposure to red light needed to happen early in the day, at least within the first three hours of waking.

How would one do that? Well, nowaday, there are a number of different red light panels and different red light sources that certainly fall within the range of red light and near. And for red light that one could use, I don't have any affiliation to any companies or products that promote or make those red light therapy.

I do own a red light panel, so I confess I have started using this protocol. I am older than forty years old. I also have been experimenting with these red light panel as a way of addressing other changes in biological tissues, for which i'm doing blood work at seta.

And i'm going to talk about that in a future episode. But that, of course, is what I call an ec data IT only relates to my experience. So today, and certainly on all episodes, the human lap podcast, we emphasize peer reviews, studies almost exclusively talking about annic data only when highlighting IT as annic data.

So if you're somebody who wants to explore red light therapy, here's what you need to do. You need to make sure that the red light source were whatever source you happen to use, whether not you purchase IT or make one. And in fact, these red light sources are very, very easy to make.

You could essentially take a bright flashlight and cover IT with a film or a filter that would only allow particular long wavelength to pass through. This would be very easy to look up online and figure out how to do this. You really do this for, you know, just a few dollars.

Or you could purchase a red light unit if that was within your budget and something that you're interested in. You want to make sure that it's not so bright that you're damaging your eyes. A good rule of thumb is that something isn't painful to look at.

And in fact, I should just emphasize that any time you look at any light or sunlight or otherwise, that's painful and makes you want to squirter close your eyes, that means it's too bright to look at without closing your eyes. Okay, that sort of a dua. But I would lows to think that anyone would harm themselves with bright light in.

Anyway, I don't just say that to protect us. I say that to protect you, of course, because you are responsible for your health. And again, retina neurons do not regenerate.

Once they are gone and dead, they do not come back. There is no technology to replace them at the current state in time. So please don't damage your retina.

So is a red light source safe to look at? If IT is not painful to look at, chances is or IT is. And yet, I would still encourage you to talk yer optometrist or optometry gist before getting into any extensive protocols.

But if you were still determined to pursue the sorts of protocols that are in the Jeffery y studies, certainly we will provide a link to those studies. Again, IT involved looking at these red light panels blinking aloud for two minutes to three minutes every morning for a period of two weeks or more. And if you're older than forty, that could very well have an effect.

If Younger, Younger than forty, excuse me, that's unlikely to have an effect, at least that was what was observed in these particular studies. The lights were not flashing. IT was continuous illumination. Again, you're allowed to blink. IT does not have to even be direct illumination and can be somewhat indirect illumination, much as we described for the use of U, V, B light before the wavelength of light is important. IT is red light and nearing for red light that is going to be effective in this scenario.

The authors of the study emphasize that IT was red light of six hundred and semi nanometer in wave life and near infrared light of seven hundred and ninety nanometers in wave life that were effective and that those wavelength be complimentary. That's probably why or maybe it's just coincidental, but it's a fortunate coincidence that a lot of the commercially available red light panels that you'll find out there combine both red light and near and for red light. However, I want to emphasize that most of the panels that are commercially available are going to be too bright to safely look at very close up.

And in fact, that's why most of those red light panels are designed for illumination of the skin and often times arrive in their packaging with eye protectors that are actually designed to shield out all the red light. So take the potential dangers of excessive illumination of the eyes with any wavelength light seriously. But if you're going to explore six seventy and seven ninety anomie light for sake of enhances neuronal function, set IT at a distance that's comfortable to look at and that doesn't force you to squint or doesn't make you feel uncomfortable physically as you need to turn away during the period of that two to three minute illumination each day.

In terms of turning away from light, i'll just briefly mention that that is not an accident to a coincidence that you have that response to very bright light. There is a so called photos avoidance pathway, and that involves cells within your retina on these gang wen cells that communicate with yet another brain station, certain area of your selling us that communicate to areas of your brain that are associated pain. So literally, that can trigger headache, and they can trigger out the skin reflects.

Biology is just beautiful in this way, too much light is bad for us. And then I can image our eyes and other aspects of our body. So if we look at a light that too bright, our eyes send a signal to the brain that gives us a sort of a headache and a desire to squint, turn away.

So that can be a useful guide in terms of aging, how bright a light should be, or at least how far away you should be from a bright source in order to safely engage with that light source. So the states I just described once again, involve the use of red light early in the day, within three hours of waking. And for the sake of improving our function, red light has also been shown to be beneficial late in the day and even in the middle of the night.

And when I say middle the night, i'm referring to studies that explore the use of red light for shift workers. I know that most people are not working in the middle night, at least I hope they are not. But some of you may do that from time to time, all nighters for studying.

I confess, I still pull all everyone's in wall to prepare things like podcast and other deadlines, really trying not to happens less than less as I get older because I think I get more disciplined and or less good at pulling all nighters. But I realized that many people are doing shift to work or where they have to work, certainly past ten pm, or maybe they're taking care of Young children in the midst the night and they have to be up. In that case, red light can actually be very beneficial.

And nowaday there a lot of sources of red light available just as red light bulb. You don't need a panel. So what i'm basically saying is that IT can be beneficial to use red lights at night. The study i'd like to emphasize on this context is entitled red light, a novel non pharmacological intervention to promote alertness in shift workers. So beautiful study, they explored the use of different wavelength of light.

So blue light of four hundred and sixty anoma ters, or red light, or dim White light, I have different brightness nesses at sea, and looked at things like milestones, how much does light of a given coLoring intensity suppress military? And they looked at court is all a stress hormones. They look at wakefulness. How much or to what degree could a given color of light increased wakefulness at different hours of the day? The takeaway from the study is very clear.

If you need to be awake late at night for a sake of shift work or studying or taking care children in etta, red light is going to be your best choice, because if the red light is sufficiently dim, it's not going to inhibit militants in production, and it's not going to increase cortisol at night cordis. All should be high early in the day, or at least should be elevated relative to other times a day if you are healthy. A late shifted increase in cortisol.

However, nine pm cortisol, ten pm cortisol is well known to be associated with depression and other aspects of mental health as a mental illness. So if you do need to be awake at nighter, even all night, red light is going to be the preferred light source. And in terms of how bright to make IT well as dim as you can, while still being able to perform the activities that you need to perform, that's going to be your best guide.

I'll provide a link to this study as well. Again, it's a really important study because IT emphasized that there are forms of light, red light provided its dim, that can allow you to stimulate the alertness that light landing on the eyes can provide, so allows you stay awake and to do whatever work that you need to do. IT does not seem to alter militant's production, so that's good.

IT does not seem to alter levels or timing of cortile production, so yet, in other case, where red light used correctly can be beneficial. Up until now, we've been talking about the effects of shining different ravels of light on the skin or on our eyes, and the downstream health consequences of that illumination. However, one of the most important goals of science and medicine is to figure out how to change the health of our brain.

And of course, our brain is contained within our skull, and therefore we can just shine light onto the outside of our head and expected to change the activity of neurons deep within the brain, unless those neurons are linked up with our eyes or with our skin. And as IT turns out, even though there are a lot of brain areas that are connected through neural circuits and hormone circuits to our eye and believe not also to our skin, many brain areas are not brain areas, such as the hypo campus, which is involved in learning in memory. Brain areas such as our neocortex.

Well, some areas of our neocortex, such as our visual cortex, are indirectly linked to our eyes. So if we shine light in our eyes, we can change the activity of neurons and anneal cortex. But there are other brain areas that are not directly or even indirectly connected to our visual system, not at least in any immediate way.

So that raises the question of how do you change the activity of neurons in the brain? Well, there's pharmacology. You can take pills.

You can inject drugs that will change the pharma logy neurons in the way they Operate in fire course and to the presence or one such instance um O P I drugs or another. There is a huge way of psycho active compounds, meaning compounds that will change the levels of chemicals in your brain. Some of those work, many of them also Carry side effects.

It's all rather indirect, meaning you have lots of different cells in different areas, your brain that utilizes the same chemicals. So a drug, for instance, to increase eotu and for sake of improving depression, will also often have the effect of reducing certain neurons output of the tony in the hippocampus, and cause changes in appetite, or changes in label, and so on and so forth. You could imagine using electrical stimulation, putting wires into the brain in stimulating specific brain areas in order to access the neuron to those brain areas.

And certainly that works and has been done experimentally and is done during the a surgery exams at a, but involves removing a piece of skull. So that's not very practical in principle. Light would be a wonderful way to modulate the activity of neuron deep within the brain.

But again, the score is in the way. Recent studies, however, have figured out ways that light can be delivered to the eyes to change global patterns of firing in the brain in ways that can be beneficial to the brain. And the work that i'm referring to now is mainly the work of Lewis gh at MIT massacres institute of technology and her colleagues.

And what they discovered is that there's a particular pattern of brain activity called gamma activity. Gama activity is one so called the wavelength of electrical elective in the brain, not wavelength of light, the wavelength electrical activity in the brain that can be restorative for certain aspects of learning and memory, and can actually help create molecular changes in neons that lead to clearance of debris and even reductions in age related cognitive cline. So the way to think about brain waves and brain isolation is that neurons are electrically active that involves chemicals at sea, and they can be active in very slow, big wave forms.

So you can think of your delta waves, meaning, so you can imagine a wave of electrical activity that comes along very infrequently. So are given on fires, and then some period of time later fires, and then some period of time even later fires. Or you can imagine that that same cell is very active.

Fires, fires, fires, fires, fires. You can image it's firing very often. It's going to be short wave ly, right? Shorter gaps between firing or if it's firing very seldom he's going to think about that as longer wavelan firing. Turns out that gama waves are one pattern of firing that leads to downstream meta lic functions and biological functions that end up clearing away debris that associated with aging in cells, and that also lead to molecular changes that enhance the kind of youthfulness of neurons, so to speak.

How do we induce gamer isolations within the brain? Well, what lev sigh and colleagues have beautifully shown is that by delivering certain patterns of light flicker, so light is going on and off at a particular frequency, the brain as a whole starts to in train, meaning IT matches to those particular patterns of light flicker, even though many of the brain areas that do this are not directly within the visual system or visual pathway. So the studies that are referred to are several, but the one that i'd like to highlight is entitled the gamma and training, buying higher order brain regions and offers neuro protection.

What they essentially did was to expose subjects to forty hurts, which is a particular frequency. Of illumination to the eyes. So it's like goes on, like goes off, like goes on, like off at a frequency of forty hurts.

And when they did that, and they recorded the activity of neurons within the brain, not just within the visual areas of the brain, but within other areas as well, they observed increased gma isolations, meaning that the electrical activity of the brain at large started to match to the patterns of light that were delivered to the eyes. This is really exciting, a very unique from the different types of photo therapies that we've been talking about up until now. All the patterns of phototherapy that we've been talking about up until now involved constant illumination with a given wave life.

Here, IT is wave length, generating patterns of illumination light on line off, line on line off at a particular frequency. So what they found for instances using this pattern of stimulation, and by the way, the stimulation was called janus gamma, and training using centers stimulation, so gnu s game and training using sensory stimulation, had a number of really interesting effects. First of all, IT reduced so called Emily ied places and Foster related tow emo od places and Foster a to are associated with alzheimer's and Normal age of cognitive decline.

So this is incredible, right? A pattern of flashing light delivered to the eyes creates a pattern of neuronal firing, not just individual areas of the brain, but in other areas of the brain as well, that in turn trigger molecular pathways that reduce some of the markers and the cause of age related cognitive cline and alzheimer. And in parallel to that, they observed an up regulation of some of the biological pathways that lead to enhancement of neuronal function, maintenance of synapses, which are the connect in between neurons, and so on and so on.

They have discovered and listed out a huge number of these biological facts, both reduction in bad things, so to speak, and the improvement in good biological pathways. And I find these studies so exciting because first of all, they're non invasive, right? There's no drilling through the skull.

They are very tractable in in the experimental sense, meaning that you could imagine that if forty hurt stimulation turns out to be the very best stimulation protocol to induce these gama isolations, well, great. But because it's not invasive, it's fairly easy to explore fifty hurts stimulation, hundred hurt stimulation, twenty hurt stimulation and to do that with different wavelength light. And so that's what's happening now.

The sii lab and other lab are really starting to explore the full range of variables that can impact isolations within the brain and their downstream consequences. So again, this is phototherapy, but phototherapy a very different sort that we ve been talking about up until now. It's phototherapy designed to trigger activation of biological pathway s far away from the very tissue that's being illuminated.

And IT calls to mind the same sorts of mechanisms that we were talking about earlier, where illumination of the skin with uvb light is setting off an enormous number of different cascades in different organs and tissues, including the spring, the testes, the overs and so on. So again, light has these powerful effects, both locally on the cells that the light is delivered to, but also systemic in terms of the cells that are changing their electrical and chemical outputs, are modifying lots and lots of biological programs. Is there an actionable tool related to these studies yet? Well, that all that depends on how adventures you are right now.

These studies are being explored in the context of clinical trials in people with alzheimer dementia and other forms of neuronal generation. Is IT dangerous to look at a forty hearts flickering light. Well, in general, the answer is going to be know.

However, if you're prone to epilepsy, y, for instance, staring at a flickering light of a given continuous frequency can induce seizure, right? That might surprise some of you, but IT shouldn't. Because as the study illustrates, and is anyone who's ever been out at night to a club or something illustrates, when you look at a stroke, for instance, your whole world of visual perception changes, but actually the rythm IT.

Would you perceive music, that would you perceive conversation? That which you perceive the movement of your body actually changes according to the pattern of visual flicker, in most cases. Strobe, if we're using this sort of club dancing example, your brain is in training to its outside environment.

So given the power of flickering lights to in train brain rythm, I think at this stage it's probably too preliminary to really suggest a specific protocol. I would definitely keep an eye out for these sorts of studies. They are coming out all the time.

And I think in a very short period, we are going to see specific protocols that one could potentially use even at home. And of course, these are not invasive protocols in order to place the brain into a particular state, not just for sake of offsetting your generation, but also for enhancing focus, for enhancing the transition into sleep. Another brain states as well today I covered, but I would say is a lot of information.

My goal was to give you an understanding of how light can be used to change the activities of cells organelles within those cells, entire organs, and how that can happen locally and systemically. We talked about the power of light to impact our biology at the undergoing level, neuronal level, immune level, mood at sea through both illumination of the eyes in the skin and other tissues as well. I realized that even though this was a lot of information, there are many aspects of phototherapy that I did not cover.

I know there's a lot of interest. Note days, for instance, in the use of red lite and other wavelength light therapies for ovarian health and testicular health. In fact, I get a lot of questions, such as, can red light be used to improve test astonia output? If so, is that best accomplished by shining red light on the skin or directly on the gonads, on the testicles? I'm going to cover those data at a future time.

Right now, the studies that have been done in rodents, I don't think we're easily enough translated to humans. And the studies that are happening in humans now are exciting in the sense that they hold a lot of potential, but the data aren't clear yet. However, the data using uvb on the skin of men and women in order to increase hormone, in particular testosterone, in aster's an output.

Those data, I think, are very exciting and very actionable when we talked about those earlier. So if you want more information on how phototherapy can be used, certainly we'll do another episode on phototherapy in these other contacts. If you're learning from and or enjoying this podcast, please subscribe our youtube channel. That's a terrific zero cost way to support us. In addition, please subscribed to the podcast on apple and spotify and on apple u.

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