Welcome to the huberman Lab podcast, where we discuss science and science based tools for everyday life. I'm Andrew huberman, and I'm a professor of neurobiology and Ophthalmology at Stanford school of medicine. Today. We are going to discuss light in the many powerful uses of light to optimize our health. We're going to discuss the use of
light for optimizing 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 and body into hormone 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 is Express and that is true throughout the lifespan today. I will discuss the
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 depth so that it's still of interest to
you. And I promise to give you tools, very specific
protocols that are extracted from the peer review. Literature that will allow you to use
different so-called wavelengths
which most of us think of as colors of light
in order to
modulate your health, in the ways that are most important to you.
For those of you that are thinking that the use of light to
Health falls under the category of woo science, pseudoscience, or biohacking. Well, nothing could be further from the truth. In fact
in 1903. The Nobel Prize was given to Neils fincen. He
was Icelandic. He lived in Denmark for the use of photo therapy for the treatment of Lupus.
So there's more than 100 Years of
quality science, emphasizing the use of light. And as you'll soon, see that use
of particular wavelengths or colors
of light.
In order to modulate the activity of cells in the brain and body. So while it is the case that many places and companies are selling therapies and products related to the use of flashing lights and colored lights, promising specific outcomes from everything from stem cell renewal to Improvement of 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 a 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 dr. Glenn Jeffrey University College London. The Jeffrey lab is known for doing.
Earring 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 exposures to Red Light early in
the day can offset much of the vision loss that occurs in people, 40 years, or older.
And what's remarkable about these studies is that the entire duration of the therapy is just one, two, 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 allowed, those cells to replenish 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 can apply those protocols. Should you choose? But I use this as an example
of our growing understanding of not just that 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 row.
National safe, and Powerful way. I'm pleased to announce that I'm hosting to Live Events. This may the first live event will be hosted in Seattle, Washington on May 17th. The
second live event will be hosted in Portland, Oregon on May 18th.
Both are part of a lecture series entitled, the brain-body
contract during which I will discuss science and science based tools for mental health, physical health, and performance. Now, I should point out that while some of the material, I'll cover will overlap with information covered here on the huberman Lab podcast.
East and on various social media posts. Most of
the information I will cover
is going to be distinct from information covered on the podcast or elsewhere.
So once again, it's Seattle on, May 17th Portland on May 18th, you can access tickets by going to
human lab.com, / tour and I hope to see you there. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford.
It is however, part of my desire and effort to bring zero cost to Consumer information
about science and science related tools to the General Public.
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sample pack. Okay, let's talk about light. First. I want to talk about the
ex 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 to 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 cetera. The physics of light can be made very simple by just illustrating. A few key bullet points. The first bullet point is that light is electromagnetic.
Netic energy. If the word electromagnetic feels
daunting to you. Well, 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 traveling in these little wavelengths and the reason for those of you who are watching at making a little wavy motion with my hand as that's actually the way that light energy moves in Little
Waves just like sound waves are
coming at you and
And impinging on your ears, if you can hear me talking right now that is happening. Those are sound waves. Meaning the movement of air particles out there impacting your
eardrum will light. Energy is just little bits of electromagnetic energy travelling through your environment all the time
in these little waves,
and impinging
on your brain, and body and eyes Etc. And as I mentioned
before, energy can
change the way that other things behave, it can cause reactions in cells of your body. It can cause
Actions 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
ripens, that's because the electromagnetic 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, calorie is a measure of
energy. It has everything to do with how much heat
is generated when you burn a
cooler 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 electromagnetic energy, but really put that word energy into capital letters. Embed 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 wavelengths and the simplest way to conceptualize. This is to imagine that cover of that Pink. Floyd album where
there's a prism, 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 purple's
Etc. Anytime we have light in our
environment. That is so called White Light. It
includes all those wavelengths, but sunlight
And other forms of light also have
other wavelengths of light that we can't see. So when we think about the rainbow, that's just the visible spectrum of light. There are also wavelengths 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 wavelengths. Give a few examples of this
humans are not a species that can see into the
infrared.
The Spectrum, a pit viper, meaning a snake that has infrared
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 emitting infrared
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 in front.
Red goggles. Well, then you would be able to see the heat emissions of any organism, human or otherwise that could emit infrared energy. Let's take the opposite end 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, light 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.
You 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 show that
ultraviolet light viewed for just a few minutes each day or landing on the skin for just a few minutes. Each Shake can actually offset a lot of pain. It actually has the ability to reduce the amount of pain.
Pain sense by your body and we Now understand the specific circuits in the brain and body that allow that to happen. I'll talk about that and the related protocols a little bit
later. So the important thing to understand about the physics of light is that there's energy at all these different wavelengths. We only see some of
those wavelengths, which basically is to say that light impacts us, at many different
levels and the so-called levels that I'm referring to are the different
wavelengths of light, and you're
welcome to think of the different wavelengths of light as different colors.
I do understand that there are
truly colors of light that you and I can't see. And yet that have a powerful impact on your brain and
body. Now, the third bullet point to understand about the physics of light, is that different wavelengths of light because of the way that they're wave travels can penetrate tissues two different depths. This is very, very important. Today. We're going to talk a lot
about red, light therapies and near-infrared light Therapies.
Those are so-called longer wavelengths longer wavelength. Just think of a bigger Longer wave, right?
A bigger curve as opposed to short, wavelength light, which is going to be shorter, write a short. Wavelength light would be something like blue or green light or ultraviolet. Light
blue, green, and
ultraviolet light because it short, wavelength 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,
You were to shine UV light onto your arm. For instance. It could impact the skin on the surface of the arm and maybe some of the cells just beneath the top layer of skin, but it wouldn't penetrate much deeper
long, wavelength 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 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 it 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 conceptualize it. You think? Wait, I got a skin. There doesn't the light just bounced off. And the answer is no, because of the way that long wavelength
light
interacts with the absorbance properties of your skin. Absorbance properties are just the way that the
skin takes light energy and converts it into a different form of energy
and
Our skin is not able to
take long wavelength light, like red light, and near-infrared light and absorb it, but the tissue is deeper in your body can. So if you shine red light or near infrared light on to 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 layers of skin into the
deeper layers of skin and can even make it into the deep layers of your
arm.
And as we start to transition from the
physics of light to the biological impacts of
light, just understanding that the different wavelengths of light impact. Our tissues at different levels, literally at different depths will help you better understand how light of different colors of different intensities and how
long you are exposed to those colors and intensities 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.
And have them land and be absorbed
at tissues deeper in your body. Well, it turns out that different wavelengths of light are also best absorbed by particular so called organelles within your cells. What are organelles? Organelles are the different compartments and different functions within a given cell. So, for instance, your mitochondria, which are responsible for generating
ATP and energy in your
cells.
Those exist at a particular depth at a particular location within a cell. They're not all at the cell surface. They sit somewhat deeper in the cell, the
nucleus of your individual cells contains DNA. And that sits at a particular depth or location within your cell.
Different wavelengths 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 mitochondria or the nucleus or the different aspects of your cells that are responsible for different functions.
This is exquisitely important and it's exquisitely powerful. Because as you'll learn today, particular wavelengths of light, can be used to stimulate the function of particular organelles 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 our cells,
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 modulate our
Biology light would be the sharpest and 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.
Wavelengths 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 metal table, because it's reflecting a lot of light of particular wavelengths,
if that table were pitch-black. However,
it wouldn't reflect quite as much and you would be able to comfortably 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 it were 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 absorbance properties of a given surface
will determine whether or not light energy goes and
stays at that location and has an impact on that
location or whether or not it bounces
off.
Every biological function of light, has to do with the
absorbance 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 it clear how this works by using the three primary
examples of how you take light in your environment and convert it into biological events.
We have photoreceptors in the back of our eyes. These photoreceptors come in two major types, the so-called rods and the cones. The rods are very elongated. They look like rods and the cones look like little triangles
rods and cones have within them photopigment. They have dark stuff that stacked up
in little layers. Rods, absorb light of essentially. Any
wavelength. There's some variation to that but let's just say it 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 photons. And rods are essentially what you use to see in very low. Light conditions will return more to Vision later.
The cones come in three
major varieties, at least for most people who aren't colorblind.
And you have so-called red cones, green cones and blue cones, but they're not really red green and blue in the back of your eye.
They are cones that
either. Absorb long wavelength light red that absorb medium wavelength light green or short, wavelength light blue.
The reason that they can absorb different wavelengths 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 absorbing like more than others. Well, so to the photoreceptors, meaning, the
cones are absorbing light of different wavelengths to different extents and in a absolutely incredible way. Your brain is actually able to take that information and
Eight, 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 photoreceptors in the back of
your eye absorbing light of different wavelengths, rods and cones. The other place. Of course, where light can impact our body is on our surface, on our skin and skin has pigment to we call that pigment. Melanin. We
have within our skin, multiple cell types, but in the top layer of skin, which is called the epidermis, we have crap, no sites and we have
melanocytes and the melanocytes are the cells that create pigmentation.
The skin and of course, there is wide variation in the degree to which there's 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 toward the equator
tend to have more melanocytes
activity than people who are located at the North Pole, and of course, people live at different locations throughout the Earth, regardless of their genetic
background or where they were born. And
so, as you all know with light exposure, those melanocytes will
turn on.
On genetic programs and other biological
programs that lead to enhance pigmentation of the skin, which we call Tanning the way they do. That is by absorbing UV light specifically. So with melanocytes, we
have a very specific example of how a pigment
absorbs light of a particular length. In this case, ultraviolet short, wavelength 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 photoreceptors. We have melanocytes. 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 of 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
spleen, but the
spleen still responds to light information through indirect
Pathways and those indirect 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 organelles, your 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, onto your photoreceptors impact, in the photoreceptors of your eye, or it can be indirect. It can
be light arriving on your
Photoreceptors the photoreceptors than informing another cell type, which informs another cell type, which then relays a signal and kind of a Bucket Brigade, manner off to the spleen and says to the spleen. Hey, there's a lot of UV light out here. We're actually under stress. In fact, there's so much UV light that you need to activate an
immune program to protect the skin and in response to that. The spleen can deploy certain signals in certain cell types to go out and start repairing skin that's being damaged by UV light. So we have
Signals that we have indirect signals, but in every case, it starts, with light of particular, wavelengths, being absorbed by particular pigments or properties of the
surfaces that those light waves land on.
And as you recall from our discussion about the physics of light.
Remember, it's not just about light impinging. On the surface of your body like can actually penetrate deep to the skin and access at least certain tissues and cells of your body. Even
In though, you can't see those wavelengths of light, they are getting into you all the time. So perhaps, the best way to wrap
this discussion about the
physics and 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 impacting the surface
of your body. But many of those signals are being taken by cells at the
surface of your of your body. Meaning your
Lana sites in your skin and the photoreceptors of your eyes
and then being passed off as a set of instructions to the other organs and tissues of your body,
like an impact, our biology in it, very fast moderately, fast
and slow ways,
but even the slow ways, in which
light can impact, our biology 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 lit
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 stumble out and it's lighter out in the next room and it takes me a while to wake up. Ah, but if
we were to move you from a room, that
was very dark to very
bright, a signal
conveyed, from your eyes to an area of your brain, stem called the locus coeruleus would cause
Release of adrenaline,
similar to the release of adrenaline, if you were to be
dropped into very, very cold water, all of a sudden, you just an immediate wake up signal to your brain and body. So
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 in the environment, not in the sort of snapshot acute sense, but averaging the amount of light in your 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, our so-called sir. Can you will rhythms cercano rhythms are literally a
calendar that exist within your body.
That uses not numbers but amounts of hormones that are
released into your brain and body each day and each night as a way of knowing where you are in the 365 day calendar year. Now that might seem kind of crazy but it's not crazy. The
Earth travels around the Sun once every
365 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
if 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
or not you were in the northern hemisphere, the southern hemisphere,
but nonetheless
in short days, you have more Darkness, that's obvious.
And if you understand that light arriving on the eyes,
Is absorbed by a particular cell, type called the intrinsically,
photosensitive ganglion cells, just a name. You don't need to know the name. But if you want, is the so-called intrinsically, photosensitive ganglion cell also called the melanopsin cell, because it contains an option, a photo pigment that absorbs short, wavelength light, that arrives through sunlight, those cells,
communicate to particular stations in the brain
that in turn, can connect to your so-called pineal gland, which is this little pea-sized gland in the
Of
your brain that releases a hormone called melatonin. And the only thing you need to know is that light activates these particular cells, the intrinsically photosensitive, melanopsin
cells, which in turn shuts down the production
of melatonin 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 melatonin release will be much longer because as I mentioned before, light inhibits, it shuts down melatonin.
Whereas 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 melatonin production, what you'll find is that the duration of melatonin released from the pineal is much shorter.
So melatonin 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 melatonin 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, this is beautiful at least to me. It's 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 melatonin and melatonin is well known for its role in making
us sleep each night and allowing us to fall asleep. Many of you have probably heard before, I am not a big fan of melatonin,
supplementation for a number of reasons, but just as a quick aside,
The levels of melatonin that are in most supplements
are far too high to really be considered physiological. They are indeed super physiological and most cases and melatonin can have a number of different effects. Not just related to
sleep, but that's supplemented melatonin
here. I'm talking about our natural production and release of melatonin, according to where we are in the 365 day. Calendar year, endogenous, melatonin meaning the Melatonin that we make within our bodies naturally, not melatonin.
Supplemented has two general categories of effects.
The first set of effects are so called regulatory effects. And the others are protective effects. The regulatory effects are for instance, that melatonin can positively impact bone mass. So melatonin can, for instance, turn on the production of
osteoblasts, which are essentially stem cells, that
make more
bone for us, that make our bones stronger and that can replace damaged aspects of our bone.
Melatonin is also involved in maturation of the gonads during puberty the
ovaries and the testes,
although their the effects of melatonin tend to be
suppressive on maturation of the ovaries and testes.
Meaning, high levels of melatonin tend
to reduce
testicle volume, and reduce certain functions within the testes, including sperm production, and testosterone production. And within the ovaries
melatonin can suppress the maturation of eggs, Etc. Now,
I don't want anyone to get scared. If you've been
Melatonin most the effects of melatonin 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
and doggedness melatonin. And that is healthy to keep them out of puberty until it's the right time for puberty to happen.
So melatonin can increase bone mass, but reduces gonad Mass.
So to speak, it's going to have varying effects, depending on the
Those and levels of other hormones and other biological events in the body, but as you can see, melatonin has these powerful regulatory effects on other tissues? I should
also mention that melatonin is a
powerful modulator of placental development. So for anyone that's pregnant. If you're considering melatonin supplementation, please, please, please talk to your OBGYN. Talk to your other doctor as well. You want to be very, very cautious because of the powerful effects that melatonin can have on the developing fetus and placenta for people that are not pregnant. In fact, all
people melatonin.
In has a powerful effect on the central nervous system, as a whole, your brain. And spinal cord are 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 melatonin. Melatonin is thereby associated with the dark phase of each 24-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 detailed to get into today.
So melatonin is regulating how awake or asleep we are. It tends to make us
more sleep. Incidentally.
It's regulating our timing of puberty and it's regulating how our gonads the
He's in over his function, even in adulthood to some extent. And it's regulating bone mass.
As I mentioned before, melatonin also has protective effects. It can activate our immune system. It is among the most potent
antioxidants. So it is known as 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 melatonin has anti-cancer properties. That doesn't mean that just cranking up the levels of melatonin by supplementing it.
And
we're by spending time in darkness and not get any light, which would, of course inhibit. Melatonin is going to be beneficial for combating cancer. That's not the way it works. It is actually the rise and fall of melatonin every 24 hour cycle and the changes in the duration of that melatonin signal throughout the season that has these anti-cancer and antioxidant
effects. So, when we think about light impacting our biology, the reason I bring up melatonin as the primary example of that is a
because melatonin
Impact. So many important functions within our brain and body, but also because hormones in general, not always. But in general are responsible for these slow
module ettore effects on our biology.
And so, I'm using this as 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 melatonin is the transducer of that
signal. So at this point, we can say, light powerfully
modulates melatonin. Meaning it shuts down. Melatonin. Melatonin is both beneficial.
For certain tissues and suppressive for other tissues and functions. What should 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 the 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 pineal sits deep in the brain
and like can't access the pineal directly at least not in
humans. So in order to get light information to
the pineal and thereby get the proper levels of melatonin, according to the time of year.
We should all try and 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 affective disorder, which is a seasonal depression
or
Feel low during the fall and winter months, there ways to offset this. We did an entire episode on mood and circadian rhythms where we describe 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 nonetheless
changes in melatonin meaning changes in the duration of melatonin release across the
year are normal and healthy. So provided that you're not suffering from depression. It's going to be healthy to somewhat modulate. Your amount of indoor and outdoor time across the year.
Are
the other thing to understand is
this, very firmly established fact, which is light powerfully inhibits melatonin.
If you wake up in the middle of the night and you go into the bathroom and you flip on the lights
and those are very bright, overhead fluorescent lights,
your melatonin levels, which would ordinarily be
quite high in the middle of the night because you've been eyes closed in the dark. Presumably will
immediately plummet to near zero or zero, we would all do well regardless of time of year to not
Destroy our melatonin in the middle of the night in this way. So, if you
need to get up in the middle of the night and use the restroom, 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.
Melatonin needs to come on early in the night. It actually starts
rising in the evening and towards sleep. But then as you close your eyes and you go to sleep, melatonin levels are going to continue to rise at least for several hours into the night.
Again, if you get up in the middle of the night,
really try hard
not to flip on a lot of bright lights if you do
that. Every once in awhile, it's not
going to be a problem. But if you're doing that night
after night, you are really disrupting this fundamental signal
that occurs every night
regardless of winter spring summer
Etc. 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
Months as the summer
months. There are functions that are specifically
optimal for the shorter days of winter and their 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 that are doing
shift work, what I can say is try and avoid getting bright light in your
eyes in the middle of your sleep cycles, even if you're sleeping in the middle of the day because you have to work at night if you wake
up during that bout of sleep, really try
hard to limit the amount.
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 outside to you. You would want to close the blinds and limit artificial light inside.
One way to bypass 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 dimming the lights are turning them off.
The other is, if you are going to use light using long wavelength light
because as you recall these intrinsically photos,
The melanopsin cells within your retina that convey, the signal about bright light in your environment to impact melatonin to shut down. Melatonin respond to short wavelengths of light. So red light is long, wavelength 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 of the night. Well, then you would probably
not reduce melatonin at all. Unless those red lights in Amber.
Lights are very very bright. Any light provided. It's bright enough. Will shut down melatonin production.
One final point about melatonin and this relates
to melatonin supplementation as well.
Is that now that you understand how potently melatonin
can impact things like cardiovascular function, immune function, anti-cancer properties, bone, mass. Gonad function etcetera. You
can understand why it would make sense to be cautious about melatonin supplementation, because supplementation tends to be pretty static. Its X
number of milligrams.
Per night, whereas normally endogenously, the amount
of melatonin that you're releasing each night is changing according to time of year, or
if you happen to live in an area where there isn't much
change in day length across the year. So, for instance, if you live near the
equator, well, then your body is accustomed to
having regular amount of melatonin each night.
When you start supplementing, melatonin, you start changing the total amount of melatonin, obviously, but you're also changing the normal rhythms in. How
Much Melatonin is being
released into your brain and body across the 365-day calendar year. So,
while I'm, somebody who readily Embraces
supplementation in various forms for things like sleep and focus
etcetera 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-counter. You, just go into a pharmacy or drug store or order online this hormone, which is known to have all these powerful effects.
So I get very
He concerned when I hear about
people taking melatonin, especially at 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 of 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. Now you could imagine at least two mechanisms by which this occurs the first mechanism, we could easily map to melatonin and the fact that melatonin is suppressive to various aspects of the so-called gonadal axis, which is basically a fancy way of saying that melatonin inhibits testosterone and estrogen output from
the testes and from the ovaries. I
just want to remind people that both males and females
make test.
Throne 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 for mating behavior. There's a
broad misconception that
testosterone is involved in mating behavior and estrogens vault 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 discuss this on the episode on.
Mising testosterone and estrogen. So if you'd like more details on that, please see that episode of The huberman Lab podcast.
Okay. So if melatonin is suppressive to the
so-called gonadal axis and reduces overall, levels of testosterone and estrogen in males and females and a
light inhibits melatonin, then when there's more light than there's less melatonin and more
hormone output from the
gonads 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 operates in, parallel to the light
suppression of melatonin 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 melatonin as sort of a break
on these reproductive
hormones, the second mechanism is more like an accelerator
on those hormones 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 UV Blue Light. So short wavelengths of light can trigger increases in testosterone and 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
Of light to the eyes. It turns out that it is the exposure of your skin, to particular wavelengths of light.
That is triggering
increases in the hormones testosterone and estrogen leading to increased 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 clothes on or ornaments on if you're somebody who has earrings and so forth.
Your skin is actually an endocrine organ. Meaning it.
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 going to 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 2021 entitled skin, exposure to UVB, light induces, a skin brain, gonad axis
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 the study also
explores 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 UV B, meaning, ultraviolet, blue lights, are short, wavelength light 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.
Tyrone, 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 as these data
indicate, and mice. Tended, to seek out mating more and mate. More. There were also increases in gonadal weight, literally increases in testy size and in ovarian size,
when mice were exposed to this,
UVB, light
past a certain threshold. Now, as I mentioned before, the study also looked at humans, they did not. Look at testy
size, were ovarian size in the human subjects. However, because they are
humans, they did
address the psychology of these human beings and address whether or
not they had increases
in, for instance, aggressiveness or in Passionate feelings, and
how their perception of other people
changed, when they were getting a lot of UVB, light exposure to the
And 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
UVB exposure increased these so-called sex steroid
levels in mice and
humans. The sex story hormones. When we say steroids. We don't mean,
anabolic steroids taken exoticness Lee. I think when people hear the word steroids, they always think, steroid abuse or
use rather steroid hormones, such as
As testosterone and estrogen went up, when my sir, humans
had a lot of UVB exposure to their skin. Second of all,
UVB light exposure to the skin, enhanced female attractiveness. So that perceived attractiveness of females by males and increase the receptiveness where the desire to
mate in both sexes.
UVB, light exposure also changed, various aspects of female biology related. To fertility in particular, follicle growth, follicle and egg.
A curation are
well-known indices of fertility. And of course correlate with the menstrual cycle in adult humans and is related overall
to the propensity to become pregnant,
UVB, light exposure, enhanced maturation of the follicle,
which 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 look at mice and
humans is terrific. I think that oftentimes 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
UV light. That was equivalent to about
20 to 30 minutes of midday sun exposure. Now, of course, where you live in the world, will dictate whether or not that
midday sun is very, very bright and Intense, or is less bright. Maybe there's cloud cover Etc. But
since imagine that most people are interested.
Did in the 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 or the human subjects.
What they did is they had people. First of all, establish a Baseline. And the way they establish a baseline was a little bit unusual but will make perfect sense to you. They had people wear 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 out on this podcast before, it's
pretty unusual that you'll get enough, UVB exposure from
artificial lights throughout the day. And in the morning, you need a
lot of UVB exposure, or we should be getting a lot of UVB
exposure to our eyes and to our face, into our skin. Throughout the day provided. We're not getting
sunburned. 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 10 p.m. And 4 a.m. That even a tiny bit of UVB
exposure from artificial sources can mess us up in terms of our sleep and our energy levels and so on. And that's because of the potent effect of 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 20 to 30
minutes Outdoors. They had people wear short sleeves. No hat, no sunglasses.
Some people wear sleeveless shirts, they encourage people to wear shorts. So they were indeed wearing clothing. They were not naked and they were wearing clothing. That was
culturally in situationally appropriate, at least for the part of the world
where the 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 30 minutes, two or three times.
Week in a minimum of clothing. And
yet still wearing enough clothing that
is culturally appropriate. They were outside. They weren't sunbathing flipping over on their back and 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 a hat of any kind. Just getting a lot of sun exposure to their skin.
They did this for a total of 10 to 12, UVB treatments. So this took several weeks, right? It took
about a month. If you think about it, two or three times per week, for a total of 10 to 12, UVB treatments. These treatments of course 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 10 to 12 of these
UVB light exposure.
Sunlight type treatments.
They did this by collecting blood samples, throughout the study, and they saw significant increases in the hormones beta estradiol, which is one of the major forms of estrogen progesterone. Another important steroid hormone 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 UV exposure.
Compared to individuals from countries with high UV exposure. Now, this ought to make sense. If we understand a little bit about how the skin functions as an endocrine organ,
many of you have probably heard of vitamin D3, which is a vitamin that we all make many people supplemented as well. If they need additional vitamin D3.
We all require sunlight in order to allow vitamin D3
to be synthesized and perform its roles in the body.
And it turns out that people who have
Darker skin actually need more vitamin D3 and or more sunlight exposure in order to activate that D3 pathway,
then do people with paler skin.
And this should make sense to all of you. Given What You Now understand about
melanocytes that cell type that we discussed earlier because melanocytes
have pigment within them. And if you have darker skin, it means that you have more melanocytes or that you have
melanocytes that are more efficient at creating pigment.
And as a consequence, the light that lands on your skin will be absorbed by those melanocytes and less of it is able to
impact the D3
pathway. Whereas, if you have pale skin, more of the light that lands on your skin can trigger the synthesis and assist the
actions of vitamin D3.
Similarly, in this study, they found that people who had paler skin and or 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 were getting a lot of UVB
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 20 to 30 minutes per day in sunlight. In a minimum of clothing. There was an increase in testosterone observed in both men and women the
It is in testosterone were greater for people that had paler skin than darker skin. So the data, I'm about to describe also come from the same paper, but do not involve 20 to
30-minute daily sun exposure
protocols. It's simply addressing whether or not testosterone levels change as a function of time of
year.
They measure testosterone across the 12-month calendar. This study was done on subjects living in the northern hemisphere for the entire year. And so
The months of January February
March, of course, the length of days is shortest and the length 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 in the nights
are shorter and what they observed was very obvious.
They observed that testosterone levels were lowest in the winter months and were highest in the months of June July, August, and September. Now, these are very important data least to my knowledge.
Allergies are the First Data systematically exploring, the levels of sex steroid 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 and mice and the other data in this paper on humans, which illustrate that if you're getting more, UVB exposure, your testosterone levels are higher. The study went a step further and explored whether or not the amount of sunlight exposure.
One is getting to their skin, influences their psychology in terms of whether or 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. Dr. Sam or hot our who's the director of the chronobiology unit at the National Institutes of mental
health. And samurais recommendation, is that people get as much bright light exposure as they safely can in the morning and throughout the day for
sake of both 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
UV 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 a motion.
Sexual and they parse this pretty. Finally, I don't want to go
into all the details and we can provide a reference in 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 focused more on increases in physical arousal, and sexual passion. Whereas 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 and reported a
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 those interact in both directions,
meaning the hormones. No doubt, effect psychology, and no doubt the psychology these changes in Passionate feelings.
No doubt also increased or change, the hormone levels as well.
And I want to re-emphasize that there was a component of the study that had no deliberate daylight.
Sunlight exposure for 20 or 30 minutes, but rather just looked at hormone levels throughout the year and found that the increase in day length,
correlated with increases in testosterone and sexual
passion. Now, my opinion, this is a very noteworthy study because it really illustrates that Sunlight and Day length can impact the Melatonin pathway and thereby take
the foot off the brake. So to speak on testosterone, estrogen, and the desire to mate.
Eight,
it also emphasizes that
sunlight UVB
light can directly, trigger hormone
Pathways and desire to mate and mating behavior.
Now, the study went 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 UVB light exposure to the eyes triggers activation of these.
Particular neurons within the eye
and then with centers
deeper, in the brain and eventually the pineal gland to suppress the output of melatonin
and thereby to allow testosterone and estrogen to exist at higher levels because melatonin can inhibit testosterone and estrogen in this study. They were able to very clearly
establish that it is sunlight exposure to our skin.
That is causing these hormone 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 UVB light, meaning sunlight Exposed Skin. Upregulated meaning increase the activity of something called p53, which is involved in the maturation of cells and various aspects of cellular function and the cells. They were focused on where the kurata, no
sites, which you are now familiar with from our earlier discussion about the fact that
The epidermis of your skin contains mainly kurata no sites and melanocytes
sunlight exposure, increased p53 activity in the skin. And p53 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, or humans were
exposed to sunlight. So these data,
Are 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 safely possible,
but that we also need to get UVB sunlight exposure onto our skin.
If we want to activate this p53 pathway in kurata, no
sights and the
testosterone and estrogen increases that are Downstream of that p53 pathway.
So even though the gene knockout studies were done on mice.
They clearly show that if you remove p53 from the skin that these effects simply do not occur. So, in terms of thinking, about a protocol to increase testosterone, and estrogen mood and feelings of passion, the idea is that you would want to get these two to three exposures per week. Minimum of 20 to 30 minutes of sunlight, exposure
on to as much of your body, as you can reasonably, expose it to
and is a reasonably. I mean, of course you have to obey
Cultural constraints, decency
constraints. 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 in
theory because sunscreen has UV protection, it would
block some of these effects. Now, I'm not suggesting that people do away with sunscreen 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
And many people are especially prone to skin cancer. So you need to take that. Seriously. Some
people are not very prone to skin cancers and can tolerate much more sun exposure. You're probably familiar with the simple fact that if you've gone outside on the
beach with friends, some people get burned 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.
Measure on to 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 or not comes from sunlight or from an artificial
source, is the effect of UVB 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 UV be on hormones and mating. Again. This is occurring via UVB exposure to the skin
and UVB exposure to the eyes.
I want to just describe two studies that really capture the essence of these
results. I'm going to discuss these and
kind of a top Contour
fashion. I won't go into it as quite as much depth, as I did the last study, but I will provide links to these studies as
well. The first study is entitled skin exposure to ultraviolet B.
Rapidly activate systemic neuroendocrine and immunosuppressive responses
and you might hear that and think oh
immunosuppressive. That's bad. But basically what they observed is that even one
exposure to UVB
light change the output of particular hormones and neuro chemicals in the body such as corticotropin hormone and beta endorphins, which are these endogenous
opioids. We've all heard of the opioid crisis, which is people getting addicted to opioids that they are taking in drug
form Pharmaceuticals.
But here I'm referring to
endorphins that our body naturally manufacturers and releases in order to counter pain and act as
a somewhat of a
psychological Soother also because of course, physical pain. And emotional pain are intimately, linked in the brain and body.
What they found was that exposure to UVB, light increased, the release of these beta endorphins.
It caused essentially, the release of an endogenous painkiller.
Now, a second study that came out very
recently.
Just this last week. In fact,
published in the journal neuron cell Press Journal. Excellent Journal is entitled. A visual circuit related to the periaqueductal gray area for the anti nociceptor of effects of bright light treatment. I'll
translate a little bit of that for
you. The periaqueductal gray is a region of the midbrain, that contains a lot of neurons that can release
endogenous opioids, things like beta, and kefflin
things like and kefflin things like Mew opioid. These are all
Names of chemicals that your body can manufacture the act as
endogenous painkillers 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 nociceptive nociception is basically the perception or the way in which neurons respond to painful stimuli. So you can think of NOS deceptive events in your nervous system as painful
events and their I'm using a broad brush. I realized that the experts in pain will say, oh it's not a really a pain circuit etcetera etcetera, but
for sake of today's discussion, it's fair to say that NASA ception is the perception of pain. So if this title is a
Circuit related to the periaqueductal
gray, which is this area? That releases, these endogenous opioids for the anti-nausea, separate 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 intrinsically photosensitive melanopsin ganglion cells as the long name for them. But these particular neurons 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 aficionados or for you Ultra curious folks. They have names like the ventral lateral. Geniculate nucleus and the intergenic IT leaflet the name.
Don't matter. The point is that light landing on the eyes is captured by these melanopsin cells. They absorb that light, translate that light into electrical signals that are handed off to areas of the brain such as the ventral geniculate. And then the ventral geniculate communicates with this periaqueductal gray area
to evoke the release of these endogenous opioids, that soothe 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 had shown that. It is light landing on our skin. That mediates that effect. But only in part, it could explain the entire effect. This very recent study indicates that it's also light arriving at the eyes. And in this case again, UVB light
ultraviolet blue, light of the sword that comes from sunlight
that is triggering 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 of The huberman 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 UVB, light exposure to the skin and to the eyes
One involving activation of
testosterone and estrogen Pathways as it relates
to mating and another that relates to
reducing the total amount of pain that we experience in response to any painful stimuli.
So for those of you that are thinking tools and protocols, if you're somebody who's experiencing chronic pain, provided you can do it safely. Try to get some UVB exposure, ideally, from sunlight. I think the 20 or 30 minute protocol, two or three times per week is an excellent.
And it seems like a fairly low dose of UVB, light exposure. It's hard to imagine getting much damage to the skin. Of course. If you have very sensitive skin, or if you live in an area of the world, that is very, very bright and has intense sunlight
particular times of year. You'll want to be cautious. Heed the
warnings and considerations about sunscreen that I talked 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 UVB
exposure
and I want to emphasize something that I've also emphasized in the many discussions on this podcast related to sleep and circadian, rhythms and alertness, which is even on a cloud covered 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, an 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 favor to try and chase, some of that
sunlight and get into that sunlight, to expose your eyes and your skin to that sunlight, as much as
you safely can. And 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 fine to where
Eye glasses or contact lenses. In fact, if you think about the biology of the eye, and the way that those
lenses work that you will just serve to focus
that light onto the very cells that you want. Those light beams to be delivered,
to wear as 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're wearing your blue,
Workers 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 certainly is a place for blue blockers in the
evening and nighttime 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 those short
wavelength UVB, wavelengths of light that you so
desperately need to arrive at your retina. And of course also on to 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 short sleeves or long sleeves, whether or not you want to wear shorts or a 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't 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
Sure, more or fewer photons depending on for instance. If you're completely cloaked in clothing and you're just, you know,
exposed in the hands neck and face such as I am now or whether or 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 or only in the summer months and that's sort of going to depend
On whether or not you experienced depression in the
winter months. So called seasonal affective disorder. Some people have mild. Some
people have severe forms of seasonal affective disorder. Some people love the
fall and winter, and the shorter days. They love bundling up. They love the leaves. They love the snow. They love the cold, and they don't experience those psychological low. So it varies tremendously and
there are genetic differences and birthplace origin differences, that relate to 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 conjugal chronobiology unit at the National Institutes of mental health. Samurai guitar
that we would all do well to get more UVB
exposure from sunlight throughout the
entire year. Provided. We aren't burning our skin, or
damaging, our eyes in some way.
In addition to that during the winter months. If you do experience some
drop in energy
or increase in depression or
psychological loes,
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 LED 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 in the show note in the show notes caption, scuse me. This is a nine hundred and thirty-two thousand luck.
X l ux light source that's designed for drawing. It's literally a drawing box. It's a thin panel. It's about the size of a laptop, very inexpensive compared to the typical sad lamp. I actually have one in my position on my
desk all day long. I also have enough skylights above my desk.
I'm a 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 full-blown seasonal affective 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.
The morning and several times throughout the day and if it's particularly 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 UVB exposure to their skin and they want to do
that through sources other than sunlight.
And there it's a little bit more complicated. There are of course, tanning salons, which basically our beds of UVB
light. That's really all they are.
Never been to one. I know people do frequent them in certain parts of the world.
There are, of course, people are covering their eyes.
They are only getting UVB exposure to their skin typically because the UVB exposure or intensities, rather tends 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 UVB exposure. So without knowing your particular,
Stances finances, genetics or place of origin, Etc.
I can't know whether or not you need to use artificial sources. You're going to have to gauge that
meanwhile getting outside looking at and getting some exposure
of UVB, onto your skin, is going to be beneficial for the vast majority of people out there.
And in fact, it's even going to be beneficial for people. That are blind. People that are blind provided. They still have eyes often maintain these
He's melanopsin cells. So even if your low vision or no vision getting UVB exposure to your eyes can be very beneficial for sake of mood
hormone, Pathways pain reduction, and so
forth. A cautionary, note people who have retinitis Pigmentosa macular degeneration or glaucoma as well as people who are especially prone to skin. Cancers should definitely
consult with your ophthalmologist and dermatologists before you start increasing the total amount of UVB exposure that you're
From any Source sunlight or
otherwise there are additional very interesting and Powerful
effects of UVB light in particular on immune function.
All the organs of our body are inside our skin and so information about external conditions, meaning, the environment that we're
in need to be communicated to the various organs of our body.
Some of them have
more direct access to what's going on outside. So, for instance, the cells in your brain, that reside right over the roof of your mouth, your hypothalamus that
control hormone output, and then control the
biological functions that we call circadian functions. The one that change every
24 hours.
Well, those are just one or two connections. Meaning synapses away from those cells in
your eye. That perceive you bb UVB light, excuse me. Other organs of your body such as your spleen, which is involved
in the creation of molecules and cells. That combat infection. Well, those are a long ways away from those cells in your eye. And in fact, they're a long ways away from your skin. There are beautiful studies showing that if we get more UVB exposure from sunlight or from
Appropriate artificial sources.
That spleen and immune function are enhanced. And there's a very logical well-established circuit
as to how that happens
your brain actually connects to your
spleen. Now.
It's not the case that you can simply think. Okay, spleen turn on release killer cells, go out and 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 autonomic nervous system. Meaning it's below
or not accessible by conscious control. It's the thing that controls your
heartbeat, controls your breathing and that
also activates our flips on the switch of your immune system.
When we get a lot of UVB,
light in our eyes, or I should say, sufficient UVB light, in her eyes,
a particular Channel, a particular set of connections within the sympathetic nervous system is activated and our spleen, deploys immune cells and molecules.
Fuels 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 you tend to be colder
out. Well, that's true. But it's also the case, the people around you have fewer colds and
flus and that
You will get infected with fewer colds and flus, and other infections.
Because if those infections whether or not their bacterial or viral arrive, in your body, right? If you inhale them or they get into your mouth or on your skin, your spleen meets those infections with a greater output. In other words, the soldiers of your immune system, the chemicals and cell types of your immune system
that combat infection are in a more ready deployed stance. If you will
if you want to
No more about the immune system and immune
function. I did an entire episode about the immune system and the Brain in a, you can find that at huberman lab.com., We talked about, cytokines. We talk about killer cells, B cells, T cells, Etc, a lot of detail
there. So we often think about the summer months in the spring. Mom 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
Actions were just able to combat them better.
What does this mean in terms of a tool? What it means is that during the winter months. We should be especially
conscious of accessing UVB light to enhance our spleen 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 cytokines. So that when we encounter the infections, as we inevitably will write, we're constantly being bombarded with
Well, infections that we can combat those infections well and as 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 wound, healing is faster. When we are
getting sufficient, UVB exposure. Typically that's associated with the longer days of spring
and summer. It is known that turnover of hair cells. The very cells that give rise to hair cells are called stem cells. They have live in little so-called niches in our skin.
With these hair stem cells and your hair grows faster and longer days that to is
triggered by UVB exposure. Not just to the skin but to the eyes that's right. There
was a study published in the proceedings of the National Academy of Sciences a couple of years ago. That showed that the exposure of those melanopsin ganglion cells in your eyes is absolutely critical for triggering. The turnover of stem cells in both the skin and hair and also,
so it turns out in nails. So if you've noticed that your skin, your hair, and your nails, look better and turnover 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 going to essentially remove
older skin cells and replace them with new cells and all the renewing cells and tissues of our body are going to proliferate are going to recreate themselves.
More. When we were getting sufficient,
UVB light to our eyes, and also to our skin.
And so, while some of you may think of light therapies, such as red light therapies or UVB, therapies is kind of new agey or just biohacking
again phrase. I don't particularly like this notion of biohacking because it implies using one thing for a purpose that it was never intended to
have. Well, it
turns out that UVB exposure and red light as well soon. See is a very potent
Form of increasing things, like wound healing and skin health for very logical. Mechanistically, backed reasons.
So, while 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 particular light therapy that you're considering involves very local,
Sharon rather than Illuminating broad swaths of skin. And if it has no involvement with the eyes, meaning there's
no delivery of UVB or red light or the other light therapy to the eyes.
It's probably not going to be as potent, a treatment
as would a more systemic activation of larger areas of skin and the eyes. Now again a cautionary, note. I don't want people taking technologies that were designed for local application and
And beaming those into the eyes. That could be very, very bad and damaging to your retinol and other tissues. Certainly. When you taking bright light of very high intensity of any kind and getting Cavalier about
that. Typically the local illumination of say a wound or particular patch of acne 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'll talk about in a few moments most of those therapies for
I skin involve 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 replenish that with new cells. So there's 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 they're not Terror cells or skin cells, Etc versus systemic
activation across
Broad swaths of skin in the eyes. You 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 kefflin and another endogenous opioids, improving immune status by activating the spleen and so on. And so on, really are all the downstream consequence of
Illuminating, large swathes of skin. And making sure that those neurons and within the I get there. Adequate UVB, exposure, or other
Wavelength exposure,
not simply beaming a particular
wavelength of light at a particular location on the body. And hoping that that particular illumination at a particular location on the body is going to somehow change the biology at that location.
Our biology just really doesn't
work. That way. It's
possible, but in general, systemic effects through broad-scale illumination and illumination to the, I
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 affective
disorder, but many of us don't suffer from seasonal affective disorder. So I'd like to drill a little deeper into how light
impacts mood.
And here, I want to again, paraphrase, the statements of dr. Samet are at the National Institutes of mental health. I
should mention the director of the chronobiology unit at the National Institutes of mental health. And perhaps one of the top
12 to 23 World experts in how light
can
Impact mood appetite to circadian rhythms and so forth.
Samer stated on the podcast and 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. And throughout the day is, a
safely possible is going to be beneficial for mood.
There's 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 melanopsin cells in
our eye, that
bypass all the areas of the brain associated
with circadian
clocks. So, everything related to sleep and wakefulness, that's specifically dedicated to the
pathways involving the release of molecules, like, dopamine the neuromodulator that's 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 individuals.
Just opioids that we talked about before
that particular pathway involves a brain structure. Called the Perry habenula, nucleus the Perry habenula nucleus gets input from the cells in the eye that respond to UVB light and frankly to
Bright Light of other wavelengths as well because as you recall, if a light is bright
enough, even if it's not UV or
blue light it can activate those cells in the eye those cells in the eye, communicate to the Perry have been alert
nucleus and as it turns out,
Out. If this pathway is activated at the wrong
time, of each 24-hour cycle, mood
gets worse, dopamine output, gets worse molecules that are there specifically to make us feel good. Actually are
reduced in their output.
So while UVB exposure in the morning and throughout the day is going to be very important for elevating and maintaining elevated mood. Avoiding
UVB light.
Night is actually a way in which we can prevent
activation of this.
I, to Perry have binocular pathway that can actually turn on
depression to be very direct in succinct about this.
Avoid exposure to
UVB light from artificial sources
between the hours of 10
p.m. And 4 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 psychiatrist, see a trained psychologist.
I just get that
treated, but you would do especially well to avoid UVB exposure from artificial sources not just from 10 p.m. To 4 a.m., But really be careful about getting too much exposure
to UVB even in the late evening. So eight pm perhaps to 4 a.m. I can't emphasize this
enough. That if you view UVB light, you activate those neurons in your eye very potent lie and if those cells communicate to the Perry, habenula nucleus, which they do you.
Will truncate or reduce the amount of dopamine that you release.
So
if you want to keep your mood elevated, get a lot of light, UVB, light throughout the day. And at night, really be
cautious about getting UVB exposure from artificial 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 10 p.m. Or so. And for
am, in fact, even during sleep. There's a recent study that just came out in the proceedings of the National Academy of Sciences and it's entitled light exposure during sleep in pairs
cardio, metabolic 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.
Or slightly bright light. Now, many people can't fall asleep in brightly lit rooms. So they acknowledge this. These were not very brightly lit rooms. These were rooms that had just a little bit of overhead room, lighting. 100 lakhs, 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. Looks. If you
want to get a sense of how bright three Lux is vs. 100 Lux, I would encourage you to download the free app light meter. I have no.
Up to the app. It's a pretty cool app. However, I've used it for a long time where you can basically Point your phone at a particular, light
source, sun or otherwise, and you just press the button. It'll give you an approximate read out of locks, which is the light intensity that the phone happens to be staring out at that location. It's not exact but it's a pretty good back-of-the-envelope measure of light intensity.
So these subjects were either
sleeping in a very
dim room. 3 lakhs is very, very dim or a
somewhat dim room.
100 lakhs
in this 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 glucose blood sugar is regulated by insulin because you don't want your glucose levels to
be too high hyperglycemia or too low
hypoglycemia, and the hormone insulin is involved in sequestering and shuttling glucose in the bloodstream. Basically how well you manage glucose in the blood.
Stream can be
indirectly measured by your insulin levels
and it's well-known that sleep deprivation can disrupt glucose regulation by
insulin.
However, in this study subjects were sleeping the whole night through. It just so happens that some of the subjects Were Sleeping In This Very dimly lit room.
Three locks, and other subjects were sleeping in a somewhat. Dimly-lit room. 100 lakhs.
What's incredible
about this study? Is that
both rooms were sufficiently dim that melatonin.
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 melatonin levels were not disrupted and given how potently light can inhibit melatonin. This speaks to the fact that this very dim condition of three locks and the somewhat dim condition of 100, Lux was not actually perceived by the subjects. Nor was it disrupting these hormone Pathways. They also looked at glucose responses. They had people essentially,
You take a fasting glucose test in different conditions. I won't go into all the details. But here's what they found in healthy adults, even just one night of sleeping in a moderately lit environment. This hundred Lux environment caused changes increases in nighttime heart rate, which means that the sympathetic nervous system was overly
active as compared to people that slept in a completely dark or in a very, very dimly lit. Room decreases in
heart rate, variability, and here, I should point out that
Heart rate, variability or HRV is
a good thing. We want heart rate, variability. So they saw increases in heart rate, decreases
in 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 lit. Environment is disrupting the way that our autonomic nervous system is functioning.
Altering so-called autonomic tone making us less. Relaxed is probably the best way to describe it. Even though we are asleep disrupting the way that our cardio metabolic function operates such that we have lower heart, rate, variability and increased insulin resistance. This is not a good thing for any of us to experience. So, while we've mainly been talking about the
positive effects of UVB light and other forms of light.
Now, we have two examples. One from the work of hot are
And colleagues showing that UVB
exposure via the Perry habenula can diminish the output of
dopamine and other molecules that make us feel good. If that UVB, exposure is
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 eyelids, which it can
activating the
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
drones showing that during the course of a healthy deep night's sleep. Our body actually transitions through various forms of metabolic
function. We actually
experience ketosis like States, we experience gluconeogenesis. We experience different forms of
Tab lism 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 metabolism probably in sleep, but certainly outside of sleep. So we wake up and have our first meal of the day or even. If you're intermittent 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 UVB light, which is short, wavelength
light. So UV light blue light, maybe even some blue green light that's going to be short, wavelength light. Now, I'd
like to shift our attention to the other end of the
spectrum. Meaning the light spectrum to talk about red light and infrared light, which is long, wavelength light,
many so-called low level light
therapies. The acronym is
llt, low level light therapies
involve the
Use of red light, and infrared, light
sometimes low level light therapies, involve the use of UVB, but more often than not these days when we hear, llt, low level light therapy. It's referring to red light and
near-infrared light Therapies.
Low level, light therapies have been shown to be effective for a huge number of biological
phenomenon and 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 Contour of
those studies
and point out that for instance, low level light therapy. With infrared, light has been shown to be effective for the treatment of acne.
Other sorts of skin lesions, have been some really nice studies actually where they use subjects as their own internal control. So, people will believe it or not agreed to have half of their face illuminated with red light or near infrared,
light, and the other half of their face serve as 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. Meaning the accumulation of new acne cysts.
With low level light therapy, using red light and infrared light
sometimes. However, there is a resistance of
that acne to the low level, light therapy, such that people will get an initial
Improvement and then it will 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
acne and wound. Healing Etc.
Well to understand that we have to think back to the beginning of the episode where I described how long wavelength
light such
Red light, and near-infrared Light, which is even longer than red light,
can pass through certain surfaces, including our skin. So our skin has an epidermis, which is on the outside and the dermis, which is in the
deeper layers,
red light, and infrared
light can pass down into the deeper layers of our skin, where it
can change the metabolic
function of particular cells. So let's just say acne as an example
within the dermis, the Deep layers of our skin we have what are called
sebaceous glands that actually make
the oil.
Oil that is present in our skin. Those sebaceous glands are often nearby hair follicles. So if you've ever had an infected hair follicle,
that's not a coincidence that hair follicles. Tend to get infected part of
it is because there's actually a portal down and around the hair follicle. But the sebaceous gland is where the oil is created. That is going to
give rise to, for instance, acne lesions. Also in the dermis and the Deep layers of the skin are the melanocytes. They're not just in the epidermis. They're also in the deeper layers.
The
skin and you have the stem cells that give
rise to additional skin cells. If the top layers of the epidermis or damaged, those stem cells can become
activated and you also have the stem cells that give rise to hair follicles. So by shining red light or near infrared 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.
Homage to the
upper layers of the skin, the epidermis
and that it triggers certain biological Pathways within the
cells of the sebaceous gland and the stem cells within the hair cell Niche, and the stem cells and skin.
What happens is the top layers of the skin are basically burned off by a very low level of burn and or the cells in the deeper layer start to churn out new cells, which go
and rescue the lesion essentially clear out the lesion and replace that lesion with
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's sometimes cases where people will get a red blotchiness due to certain skin conditions
or some darker pigmentation that they want remover 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
sebaceous gland, the stem cells, Etc.
Well, long
wavelength light can actually get deep into the skin. I mentioned that before but can also get into individual cells
and can access the so called organelles, which I described at the beginning of the episode in
particular. They can access the mitochondria,
which are responsible for producing
ATP. Now, the simple way to think about this for sake of this discussion is that as cells age and in particular in very metabolically active cells, they
What are called? R OS is reactive oxygen species.
And as reactive oxygen species, go
up, ATP energy, production, those 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 that 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 mitochondria, which increases ATP
And directly or indirectly.
Reduces these
reactive, oxygen species, these reactive oxygen species are
not good. We don't want them. They cause cellular damage, seller deaf. And for the most part, just inhibit the way that our cells work. So, if you've heard of red light or near infrared, light therapies designed to heal skin or improve
skin, quality or remove lesions, or get rid of scars or
unwanted pigmentation. That is not
pseudoscience. That is not
Whoo science that is grounded in the very
biology of how light interacts with mitochondria and reactive oxygen
species. Some of you may also find it interesting to note that some of the cream based
treatments for acne. For instance, like retinoic acid.
Retin-A is actually a derivative of vitamin A and the pathway involving retinoic acid and vitamin A believe it or not is very similar to the Natural biological pathway by which photo pigments in the I can.
Light
information in to biological changes within those cells.
So the key Point here is that light is activating particular
Pathways in cells. That can either drive at death of cells
or can make those cells,
essentially younger by increasing ATP, by way of improving mitochondrial 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,
My red
light and near-infrared 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, or 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 infrared light so called La
LT low, level light.
Bees, for treatment of Dermatological
issues. So, anything related to skin? I will include a link to a excellent set of reviews. The first one is light emitting diodes and dermatology a systematic review of randomized, controlled trials that one includes review of a
very large number of studies came out just a few years ago in 2018. And I think it's very clearly and cleanly laid out for anyone to access. You can see the
degree of effects of red light, for
instance, on treatment of acne, or scarring,
Etc. And I'll also provide a link.
Link to another review which is low level light therapy in skin, stimulating, healing and restoring. So for those of you that are
interested again in Dermatological issues and the kind of
restoring
youthfulness and the kind of General
themes of anti aging and Longevity and how red
light therapies can be used for that. I would encourage 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 sake of treating and improving
Skin, and I mention this
because I get a lot of
questions about infrared, sauna
and Global illumination with red lights. We'll talk more about cases, where Global
illumination of your whole body. 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 high.
Hot enough temperature wise, in order to trigger some of the important effects on growth
hormone and heat, shock proteins, and some of the other things that sauna has been shown to be excellent for
that's a general statement. I realize there are some infrared
saunas that do get hot enough.
There are very few data on the use of whole body illumination with infrared saunas. They really point to any specific mechanistically supported affects almost all the positive effects that you're going to see a red light and low level light.
Peace certainly, the ones discussed in the reviews that I just mentioned 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, infrared saunas, but in general, they don't get hot enough to trigger. Most of the positive
effects that sauna have been
demonstrated to have and it's unclear at all
as to whether or not they can enhance skin quality youthfulness, restore.
You know top layers of skin that are damaged repair acne.
Etc. So more on heat saunas 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-infrared 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. Glenn Jeffrey at University College London. Who again, is a
long-standing member of the
Science Community working on visual neuroscience and who over the
last decade or so has really emphasized the exploration of red light, and near-infrared 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 eye that's responsible for translating light information into electrical signals. So that we can see we
don't
Get any
new cells after the time in which we were born.
So, the ability to keep our neurons
healthy is extremely important for our visual system. Extremely important for our hippocampus, an area of the brain involved in memory and should just mention that. Even if people don't get
Alzheimer's, there's always going to be some degree of age related
dementia. Sadly. Nobody is as cognitively sharp in the years before they die as they are 20 years before that is just never the case where all
Getting worse at thinking feeling perceiving, Etc. The question is, how quickly we are getting worse.
So, any mechanism by which we can preserve or reverse? Neuronal function, turns out to be immensely beneficial. The Jeffrey lab has published two studies in recent years, on humans, that looked directly. No pun intended at how red light, and near-infrared 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 this
effect of light on
mitochondria. 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. If it's
of the appropriate wavelength red light can do that, can get into cells, it
can access the mitochondria. It can increase a teepee.
In general any time, ATP is doing its thing to increase energy and sells its involving this thing called cytochrome C,
which is an oxidase.
Any time you hear a say SE and biology. It's going to be an enzyme. It's
involved in some process of degrading, a molecule, and creating another molecule.
Typically, so ATP. And cytochrome, C is going to give you a teepee. Now, that's a great thing, but it creates a
by-product, it breaks things down such.
You get, these are os's, these reactive, oxygen species, and those reactive oxygen species. For those of you that want to know,
are involved in things like redox, signaling and
reactive oxygen species, actually change, which genes are made in a Cell. So the goal of any treatment to keep neurons or other cells youthful
and functioning well, and to present to prevent or reverse aging is going to be to increase ATP and to reduce reactive oxygen species and
And in doing so to disrupt some of the normal
Pathways associated with aging.
The Jeffrey lab approach these studies with that understanding of how mitochondria and reactive oxygen species in a
teepee 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 20s or 40 years old or older view red light of about 670 NM 670 NM would appear
red to you and me.
They had they had them do that. Scuse me at a distance
that was safe for their 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 at about a foot away
from a red light that was of 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 12 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 28 years old to about 72 years old. The major findings were that in individuals, 40 years old, or older? So in the 42
72 year old
bracket, but not in the subjects younger than 40 years old. They saw an improvement in visual function that Improvement 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 Triton exam T, RI ta n, Triton exam which specifically addresses the function of the so-called short, wavelength cones. The ones that respond to green and blue light. They saw a 22 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 an
improvement of 5% or
10%. So a 22 percent Improvement in visual Acuity, even though it's in this very specific form of visual testing this Triton exam or this Triton 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 retina, but we don't tend to lose cones. 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 ganglion cells
cones for whatever reason are pretty resilient to age related loss. However, because rods and cones, both are not just among the
most metabolically active cells in your entire body, but the most metabolically active cells,
I was in your entire body. That's right. Your
rods and cones are the cells that demand. And that use the most energy of all the cells in your body. Not your skin cells, not your spleen cells, not your stomach cells, even if you
talk a lot, not the
cells. They're 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 rods, and cones,
and to rescue the function of
this particular cone type, the short wavelength, and medium wavelength
cones, which if you think about the study is a little bit surprising because it was red light and
near-infrared light. Not short, wavelength light that was used in order to create this Improvement in seller function. But if you step back a little bit
further, it makes
Makes sense because there's nothing specific about the red light. In the sense that it's not, that it gets delivered only to Red
cones, that red light, and near-infrared light is being absorbed by all the photoreceptors, within the eye, the rods and the blue cones and the green cones. And the red count is just at the red cones, absorb that light best. So
the important takeaway here is that viewing
red light and your infrared light at
a distance at which it is safe for just a couple of minutes.
Each.
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 it again, the retina including your photoreceptors are not just connected to your brain. They're not just near your brain. They are actual central nervous system tissue. They
are the only two pieces of your brain minear. Neural retinas are the only two pieces of your brain that reside outside your scholar at least outside the cranial
Vault. 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 these cells because they reside
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 describe the non-invasive applications of light
to try and restore the function of those cells as well.
So a little bit more about the studies from the Geoffrey lab, one of the things that they observed was a reduction in so called
drusen, Dr. U SE, n
drusen, our little fatty deposits, little cholesterol
deposits that accumulate in the eye 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 clogging a veins and arteries is not a good
thing. Well, our neural retina being so metabolically,
active requires a lot of blood flow. It's heavily
vascularized and drusen are a special form of cholesterol that accumulate in the eye as it turns out these red light and near-infrared light therapies explored by the Jeffrey lab were able to actually reduce or reverse some of the accumulation of Drew's.
And and so, in addition
to reducing reactive oxygen species, the
idea in mind now is that red light may actually reduce cholesterol deposits
and reactive oxygen species in order to improve neuronal 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 to 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, nowadays. 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-infrared light that one could use. I
don't have any affiliation to any companies or products that promote or make those red light Therapies.
I do own a red light panel. So I
confess I have started using this protocol. I am older than 40 years old. I
also have been experimenting with these red light panels as a way of addressing other
changes in biological tissues for which I'm doing blood work, etc. And I'm going to talk about that in a future episode, but that of course is what I call Annika data, it only relates to my experience. So today and certainly on all episodes of the human Lab podcast. We emphasize peer reviewed studies, almost exclusively talking.
Anak data only when highlighting it as anecdotal.
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 that red light
source, whatever Source you happen to use whether or 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 wavelengths to pass through. This would be very easy to look up online and figure out how to do this. You probably do this.
Us 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 eye. 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 lights or sunlight or
otherwise, that's painful and makes you want to squint or close your eyes. That means it's too bright to look at without closing your eyes. Okay, that's sort of a duh, but I would loathe to think that anyone would harm themselves with bright light in any
Way, 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, retinal neurons. Do not regenerate. Once they are gone and dead. They do not come back. There's no technology to replace them at this current state in time. So, please don't damage your retinas.
So is a red light source, safe to
look at. If it is not painful to look at
chances are it is? And yet, I would still encourage you to
talk to your optometrist or ophthalmologist before getting into any extensive. Protocols.
Al's.
But if you are still determined to pursue the sorts of protocols that are in the Jeffrey, studies certainly will provide a link to
those studies again, it
involves looking at these red light panels, blinking allowed for 2 minutes, to 3 minutes every morning for a period of two weeks or more. And
If you're older than 40, that could very well have an effect. If your longer younger than 40, scuse 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. It can be somewhat indirect illumination much as we described for the use of UVB light before,
the wavelength of light is important.
It is red light, and near-infrared light that is going to be
effective in this scenario.
The authors of this study emphasized that it was red light of 670, NM in wavelength, and near-infrared light of 790
nanometers in wavelength that were
effective. And that those wavelengths could be complementary. 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-infrared light. However,
I want to emphasize that most
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 oftentimes arrived in their packaging with I 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 of light,
seriously, but if you're going to explore 670 and 7, 90, nanometer
light Force,
Of in enhancing neuronal
function. Set it at a distance that's comfortable to look at and that doesn't force you to squint or does it make you feel
uncomfortable. Physically as if 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 or a coincidence that you
have that response to very bright light. There is a so-called photic avoidance
pathway and that involves cells within your retina. These ganglion cells that communicate with. Yet another brain station,
certain area of your Thalamus that
communicate to areas of your brain that are associated with pain. So literally that can trigger
headache and that can trigger the squint reflex.
Biology is just beautiful in this way too
much. Light is bad for us and that it can
damage our eyes and other aspects of our body. So if we look at a light, that's too bright or I send a signal to the brain that gives us a sort of a headache and a desire to squint and turn away
so that can be a useful guide in
terms of gauging, 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 studies I just described once again, involve the use
of red light early in the
Within three hours of waking and are for the sake of improving, neuronal 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 of 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 of the night. At least. I hope they're not. But some of you may do that
from time to time all-nighters for studying, I confess. I still pull all-nighters every once in a while to prepare things like podcasts and other deadlines,
really, try not.
It to happens, less and 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 work where they have to work, certainly past 10 p.m. Or maybe they're taking care of young children in the
middle of the night, and they have to be
up in that case. Red light can actually be very beneficial and nowadays. There are a lot of sources of red
light available, just as red light bulbs. 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 in 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 wavelengths of light. So blue, light of 460 NM or red light, or dim, white light of different brightnesses, Etc, and looked at things like melatonin, how much does light of a given
color? And intensity suppress, melatonin? They looked at cortisol a stress.
Stress hormone, they looked at wakefulness. How much, or to what degree, could a given
color of light, increase wakefulness, at different hours of the day. The takeaway from
this study is very clear. If you need to be awake late at night for sake of shift work or studying or
taking care of children, etcetera. Red light is going to be your best choice
because if the red light is sufficiently dim, it's not going to inhibit melatonin production and it's not going to
increase cortisol at night.
Cortisol 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, 9 p.m. Cortisol, ten PM cortisol is
well known to be associated with
depression and other aspects of mental health. Russia has a mental illness. So, if you do need to be awake at night or 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 it allows you to stay awake and to do whatever work that you need to
do. It does not seem to alter melatonin production. So that's good. It does not seem to
Alter levels or timing of
cortisol production. So
yet, another case where red light used
correctly can be beneficial
up until now. We've been talking about the effects of shining different wavelengths 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't just shine light on to
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 RI and believe it or not. Also to our skin.
Many brain areas are not
Brain areas such as the hippocampus which is involved in learning and 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 on our eyes, we can change the activity of neurons in our neocortex,
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
Change the activity of neurons in the brain. Well, there's pharmacology. You can take pills. You can inject drugs that will change the pharmacology of neurons in the way. They operate in. Fire course. Antidepressants are one, such instance,
opioid drugs are another. There's a huge array of
psychoactive 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 of your brain that utilize the same
chemicals. So a drug for instance to increase serotonin for sake of improving. Depression will also often have the effect
of reducing certain neurons output of serotonin in the hippocampus and cause changes in appetite or changes in libido and so on and so forth. You can imagine using electrical stimulation, putting wires into the brain and stimulating specific brain areas in order to activate the neurons in those brain areas, and certainly that works and has been done experimentally and is done.
During neurosurgery exams Etc, 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 neurons deep within the
brain. But again, the skull 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
Referring to now is mainly the work of leeway
PSI at MIT, Massachusetts Institute of Technology and her colleagues.
And what they've discovered is that there's a particular pattern of brain
activity called gamma activity,
gamma activity is one so called the wavelength of electrical
activity in the brain. So not wavelengths of light, but wavelengths of electrical activity, in the brain that can be
restorative, for certain aspects of learning and memory, and
can actually help create molecular changes in.
And that lead to
clearance of debris and even
reductions in age-related cognitive decline.
So the way to think about brain waves and brain oscillations, is that
neurons are electrically active, that involves chemicals Etc
and they can be active, in very slow, big wave forms. So you can think of delta waves meaning. So you can imagine a wave of electrical activity that comes along very infrequently. So a given
neuron fires and
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 imagine it's firing very often. It's going to be short wavelength right shorter gaps between firing or if it's firing very
seldom. You're going to think about that as longer
wavelength firing turns out that gamma waves are one pattern of firing that lead to Downstream.
Metabolic functions and biological functions that end up clearing away debris. That's are 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
gamma oscillations within the brain? Well, what
leeway sigh and colleagues have beautifully. Shown is that by delivering certain patterns of light flicker. So, lights going on and off at a particular frequency. The brain as a whole starts to entrain, 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 I'm referred to are several, but the one that I'd like to highlight is entitled gamma entrainment binds higher-order
brain regions and offers neuroprotection. What they essentially did,
was to expose subjects 240 hertz, which is a particular frequency of Illumination
to the eyes. So, it's light goes on, like, goes off, like goes on, like, goes
off at a frequency of 40
Hertz. And when they did that,
and they recorded the
The activity of neurons within the brain, not just within the visual areas of the brain, but with in other areas as well, they observed increased gamma oscillations, 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 and 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,
Life. Here. It is. Wavelength
generating patterns of Illumination, light on light off light on light off at a particular frequency.
So what they found for instance using this pattern of stimulation and by the way, the stimulation was called Genesis gamma entrainment using sensory stimulation. So GE nus gamma entrainment using sensory stimulation had a number of really interesting effects. First of all, it reduced so called amyloid, plaques and phosphorylated, Tau amyloid, plaques and phosphorylated, Tau are
Date with Alzheimer's and normal age-related cognitive decline. So this is incredible right. A pattern of flashing light delivered to the eyes creates a pattern of neuronal firing not just in the visual 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 decline and
Alzheimer's and in parallel to that they observed an upregulation.
Of some of the biological Pathways that lead to enhancement of neuronal
function. Maintenance of synapses, which are the connections between neurons and so on. And so
on they have discovered and list out a huge number of these
biological effects. Both the 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 and in the experimental sense,
meaning that you could imagine that if 40 hurt stimulation turns out to be the very best stimulation protocol to induce these gamma oscillations. Well great. But because it's non-invasive, it's fairly easy to explore 50 hertz, stimulation hundred Hertz stimulation, 20 Hertz stimulation and to do that
with different wavelengths of light.
And so that's what's happening. Now, the scilab and other labs are really starting to explore the full range of variables that can impact.
Within the brain and their Downstream
consequences. So, again, this is phototherapy but phototherapy, but very different sort that we've been
talking about up until now, it's
phototherapy designed to trigger activation of biological Pathways 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 spleen. The testes, the ovaries and so on.
So,
Again light has these powerful effects both locally on the cells that light is delivered to but also systemically 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 sort of depends on how adventurous you are right. Now. These studies are being explored in the context of clinical
trials in people with Alzheimer's dementia and other forms of neuronal degeneration.
Action,
is it dangerous to look at a 40 Hertz. Flickering light? Well in general, the answer is going to be. No. However, if you're prone to epilepsy, 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 this study illustrates, and as
anyone who's ever been out at night to a
club or something illustrates, when you look at a strobe light, for instance, your whole world of
visual perception changes, but actually the Rhythm at which you perceive music at which you perceive conversation at, which you perceive the movement of your body actually changes, according to the patterns of visual
flicker in most cases strobe. If we're using the sort of club dancing example, your
brain is in training
to its outside
environment. So given the power of flickering lights to entrain, brain rhythms. I think at this stage, it's probably two preliminary to really suggest a specific protocol.
But 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're going to see specific protocols, that one could potentially use even at home. And of course, these are non-invasive protocols in order to place the brain into a particular State, not just for sake of offsetting neurodegeneration, but also for enhancing Focus, for
enhancing the transition into sleep and other brain States as well.
Today, I covered
What 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 endocrine level,
neuronal level immune level mood Etc. Through both illumination of the eyes and the skin and other tissues as well.
Realize 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 nowadays, for instance, in the use of red light 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
testosterone output. And 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 are 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 UV beyond the skin of men and women. In order to
increase hormone in particular, testosterone and estrogen output, those
data, I think are very
Exciting and very
actionable. We talked about those earlier. So if you want
more information on how photo therapy can be used,
certainly we will do another episode on phototherapy in these other contexts.
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A podcast much of which is unique and has never been presented publicly before. The first one is going to be May. 17th 2022 in Seattle, Washington. The second one is going to be May 18th. In Portland, Oregon to access tickets. You can go to the link at huberman. Lab.com tour. So thank you. Once again, for joining me today. For this deep dive discussion into photo
therapies, meaning the power of light to modulate, our biology and health. And as always, thank you for your interest in signs.
