Undoctrinate Yourself - #2 - Shedding Light on Circadian Biology

Episode Date: March 12, 2025

On this episode of Undoctrinate Yourself, we deep dive into the mechanisms of circadian biology in the body and the impact of our light environments on these processes. We break down the importance of sunlight in health optimization and disease prevention and remediation, and the potential harms of artificial light.Support the podcast by becoming a patron: patreon.com/UndoctrinateYourselfPodcastDr. Alexis's Instagram: https://www.instagram.com/dralexisjazmyn

Hello and welcome back to the Undoctrinate Yourself podcast with me, Dr. Alexis Cowen. I am super excited to be back. And if you've joined me for my first episode, which was kind of my backstory and my why behind what I do and what I'm passionate about, thank you so much for joining me there. Now I'm really eager to dive into some science and really get into the meat of things because there's just so much for us to explore here. in the solo capacity as well as with guests. So right now this is going to be a solo podcast. I have, like I mentioned last episode, some great guests lined up for you, but I really want to kind of set the stage and provide you guys with some basic and fundamental information that I think we need to all know moving forward so that we are informed and can be inquisitive and

discerning when we're listening to people speak and trying to understand and assimilate scientific information. So today's episode is going to be on all things light and circadian biology. And we're going to get into the very nitty-gritty details of both of those very big topics. But I really wanted to begin by kind of painting a picture for you all. So just imagine. It's 200 years ago. The year is 1823. Electricity hasn't yet been commercialized. So, you know, you go about your day, maybe you live in a village or a small town, and, you know, you go work a job in some sort of manual labor or textiles position, and, you know, you go there during the day. You're up, perhaps around dawn, eating breakfast, going to work. You're coming home before it gets dark. You're, you know,

eating a meal with your family and the sun is setting. Let's say that it's around the summertime in the northern hemisphere. So let's say the sun is setting around 8.30. You start winding down to go to bed because the light that you're limited to at night is going to be candle, firelight, essentially candle and fireplace. So once it gets to this time of night, you're really starting to wind down and get ready for the next day. And you're exposed to almost complete darkness all night until when you wake up in the morning with the sun. This was roughly the existence of our human species for the entirety of the time that our species has inhabited Earth, which the modern human is estimated to be around 200,000 years old.

And our discovery of fire roughly coincides with that. Fire seems to have been discovered maybe between 300 and 500,000 years ago. And before we discovered fire, you know, quote unquote discovered, I'm sure we probably happened upon fire in response to lightning storms and such that could cause fires within our environment and then we learned how to harness it. But regardless, before this period of time, the light that we were exposed to within our environments was limited to a very select number of sources. The primary one being the sun, which goes without saying. The sun is providing the vast majority of the light that we're encountering, assuming, you know, that we're living this time 200 years ago or any time prior to that. The sun is what our lives revolved around. The sun provided all of the light that we needed to navigate our terrains during the day.

And when the sun went down, our nervous systems also deregulated and begin going down to kind of enter a more restorative time of the day where we're getting sleep. We're recovering from our day and we're preparing for the next. day. So the sun being the primary source of light during this time, other sources of light that we could encounter would include the moon and stars. So depending on the phase of the moon, you're going to get different intensities of light, and we're going to get into the different intensities of light depending on the source. So the moon and the stars, other sources of light. We can also have bioluminescence, so there are certain marine microorganisms that can create very low levels of light in the ocean. And so that's another source, but I would say it's pretty minimal. Also,

of course, like fireflies in the summer here in the northeast are a form of bioluminescence, but again, this is not like a major source of light. And then finally, we would also have lightning as a source of light. But again, kind of fleeting, not a primary source of light in our environments, more so an anomaly that would happen every so often. By and large, the sun is and was providing light for our species since the dawn of life on Earth. So something that we don't think about a lot and that's not discussed is that the sun has really been the driver of evolution on the planet. And the sun has been crucial for the regulation of the functions of life and the functions of organisms. So let me give you an example. Life on Earth has always encountered cycles

of light and dark, not one or the other. So there's never been a period of time where it's just light all the time, you know, forevermore and dark all the time. It's actually both that serve as really crucial stimuli that regulate biological life. And life evolved to use darken light as a way to understand the environment that the organism finds itself in. They serve as major landmarks about what time of day it is, what the environment is like. So for example, sun is more intense in the northern hemisphere. We have more intense sun during the summer. We have longer days.

And then as the year approaches more so towards the winter, we get shorter days and less intense sun. and those shifts are providing information to our bodies about what time of the year it is, and that creates shifts in gene expression and regulation of our metabolism and biology that's in accordance with those shifts in the environment. So now, let's fast forward to today, where we live in this modernized environment that really started after the 1893 World's Fair, which was the electrification of the world. this is when electricity was introduced into the home, and it revolutionized the way that our lives

worked. We now had the ability to harness light at the flick of a switch, and that ultimately allowed us to be more productive, which I ultimately think is more to our detriment than, you know, at least in some ways. But so with our ability to harness light within our homes, we have the ability to work at basically any time of day. We have the ability to just kind of operate society on different hours than the hours that our bodies and our biology adapted to abide by. And so you can think about life today where, you know, you go out after sundown and you go to any store, any mall, restaurant. you're in well-lit spaces, generally speaking. And that light is often bulbs like LED lights and fluorescent bulbs,

and we'll get into the difference between the different types of light bulbs and what that actually means for our bodies and how our bodies are functioning. But really in this introductory part of the podcast, I really just want to emphasize and illuminate, pun intended, just the insane changes in our light environment that our species has experienced in the past less than 200 years. So in 200 years, there's no evolution happening within our species. We're not equipped to deal with these shifts in the light environment. And I'm going to get into the ways in which our light environments are regulating our bodies,

which will then shed light on why this is an important topic to begin with. But just recognizing that we're now living under artificial light virtually day and day out and 24-7. And we do so without any regard for the effects on our health. And we also do so without any regard for the types of light that may have differential impacts on our bodies. So, for example, the sun has light that ranges from the visible to invisible parts of the electromagnetic spectrum, and we're going to unpack the electromagnetic spectrum shortly. But we basically have the range from UV through the visible spectrum, which is, you know, like Roy G. Biv. So we have UV violet up through red. Then we have the near-infrared and infrared light, which is just above red that is not part of the visible spectrum.

and that encompasses the light that we receive from the sun here on the ground on Earth. There are x-rays and gamma rays that can come from the sun, but those are filtered out by our atmosphere, so they don't reach us down here on Earth. Contrast this with certain lights that we're encountering in our indoor environments. So let's take a fluorescent bulb, for example. Fluorescent light bulbs, the classic compact fluorescent bulbs, have a very large peak in the blue and UV ranges.

of the electromagnetic spectrum. And they have these peaks in the absence of the rest of the visible spectrum, essentially. So what I'm saying is when we're under the sunlight, which is what we evolved to be under, we're exposed to a broad spectrum ranging from infrared all the way to UV. When we're under a fluorescent bulb, we're getting these very isolated wavelengths of light in the blue and UV range that is actually creating this situation where it's as if we're under an alien sun. To our bodies, we are now in an environment that is completely alien to the one in which we evolved to live. And so this is just something to keep in mind, and it's something that once you see it,

you can't really unsee it just how much artificial light we're exposed to our environments and how normalized it's become. and at the same time how normalized a lot of the chronic diseases that we're facing today have become, that it almost seems like an inevitability to develop a lot of these long-term chronic conditions, and it really makes you start to question, what are we doing unconsciously that we have somehow collectively assumed isn't affecting us and isn't harming us, but in reality is kind of going in the face of our evolutionary biology and how our bodies, were designed and how they developed to function optimally. So just with that kind of little introduction, I want to move into some of the basics so that we can

understand how light is influencing the way that our bodies are functioning. So first of all, I want to define chronobiology. So chronobiology is the study of the biological rhythms and the molecular pathways by which these rhythms are established, maintained, and impaired within our body. bodies. So chronobiology, a major focus of study within this field is the circadian rhythm, but virtually these studies are applied to all different types of rhythms within the body. So the circadian rhythm specifically refers to the 24-hour rhythms within the body. But there are other rhythms that are also occurring at the cellular level that's dictating to the cells of the body what

time of day it is essentially. But more or less, all the rhythms in the body, despite what time they're running on, are dictated by biological clocks that exist at the cellular level. And these biological clocks consist of specific molecules that serve as instruments of time. So our body is keeping time all the time. And I'm going to tell you exactly how that timekeeping is, you know, made accurate and how it's occurring molecularly. And once we start to realize that, then we can really understand how to optimize these

processes and where we're going wrong. Importantly, clocks have been actually identified in virtually every tissue within the body. But having said that, there is one master clock that exists within the entire body, and that clock is the super

chasmatic nucleus or the SCN. And that's located within the hypothalamus in the brain, The SCN actually receives direct input from the eyes. So when light is exposed to the eyes, the eyes transduce that signal directly to the SCN, and that light signature can then be interpreted by the SCN to tell the SCN what time of day it is, and then convey that message to the downstream clocks within all the other cells of the body. and by doing so, this can ensure that the SCN keeps all of the body's clocks in time with one another.

So I mentioned the circadian rhythm being the rhythm that's attributed to the 24-hour cycles of the body. So there are specific inputs that will dictate the beginning and end of each 24-hour cycle. And these inputs are known as zeitgebbers, which is German for timegivers. And the primary timegivers or zeit-gabers within the body are light, temperature, food, and kind of stimulation, like nervous system stimulation. But among those four, light actually has the largest impact on regulation via the SCN pathway. So with regards to the specifics of this SCN structure within the hypothalamus, this portion of the hypothalamus is composed of around 10,000 neurons,

and it's both necessary and sufficient for the establishment of the circadian rhythm. and solar light exposure is the source of light that we evolved to use to regulate and entrain our clocks via the SCN. And like I mentioned before, the eye can directly communicate with the SCN. Well, this occurs via this area within the eye that traverses into the brain called the retinohypithalamic tract or the RHT. So the RHT mediates increased firing within the SCN. that facilitates the entrainment of that master clock. The Rhth originates in these cells within the eye

called innately photosensitive ganglion cells or IPGCs. And these cells express the photoreceptor melanopsin. Photoreceptors are these molecules that are light sensitive, and so they're able to detect light and then transduce a signal in response to detecting that light. So melanopsin was actually initially evolved within invertebrates. and has been retained as this very, very crucial photo receptor within mammals, including us. And so specifically melanopsin is a G-protein-coupled receptor that is absolutely essential for

non-image-forming visual functions. So this is independent of actually perceiving our environment visually. It's instead really important for conveying signals about our environment to our brain. And as it turns out, like, you know, I just mentioned this melanopsin is really important for conveying the signal of solar irradiens, solar light, to the SCN for entrainment of the master clock. Specifically, melanopsin is maximally sensitive to 480 nanometer light. And we're going to get into the electromagnetic spectrum, but 480 nanometer light lies within the blue region of that spectrum. So blue light really serves as the impetus for the entrainment of that master clock's timing. And blue

light is what we would encounter in sunlight around noon. So the maximum blue light that we're going to get in nature is like noon in the middle of the summer. That's when you're going to get, you know, maximal blue light exposure that's really telling your body what time of day it is. But in general, you know, even if it's, whatever time of year it is, if it's around midday, like peak sun, that's when you're getting peak levels of blue light from the natural environment that's going to be providing the information that your body needs to entrain the superkysmatic nucleus, the SCN, and allow it to determine the time of day so that all the other clocks within the body can be entrained on that time. So interestingly, melanopsin isn't the only option that's present in

the body, and I think this is really an emerging field within the photoreception place, but there's a lot of data and information that suggests that. that we may have quite a bit of non-visual-related photoreception going on. So there's options, other options that are also like these light-sensitive receptors that are present within keratinocytes, melanocytes, dermal fibroblasts, and hair follicle cells, for example. We find these options, these light-sensitive molecules present there. And ultimately, biology is thrifty.

It's not going to put these receptors where they're not needed. And so it's just a matter of us figuring out what they're doing in those locations. But I think it's super interesting, especially because the visual options present within the eye are also present in the keratinocytes, these cells that are making keratin within our skin. And so what are these options doing in our skin? What are they sensing light for? What is the purpose of that? I think it's a very interesting and open question that we need to explore further. So now let's unpack the electromagnetic spectrum a little bit.

The electromagnetic spectrum encompasses all wavelengths of light that range from visible to non-visible. So this would include radio waves. So let's kind of start at the lowest, the longest wavelength, the lowest frequency light. This would be your radio waves. then as you start moving up the spectrum, we can then, let me pull out my notes. Then we move up to microwaves, which are the next ones after radio waves,

and also within the microwave part of the spectrum, we also have the 5G, Wi-Fi, and Bluetooth wavelengths of light. So even though we don't see and perceive these frequencies of light visually, these are forms of light that are interacting with our biology, And so you can kind of think of it as light pollution in this way, even though we can't physically see it with our eyes. So up from there, we have the infrared light, which is what you would find from if you have like an infrared or near infrared light panel. In addition to that, infrared light is what's produced by our bodies. in other words as heat.

So heat is often used interchangeably with infrared light. Within the context of our bodies, our bodies are making heat to sustain our body temperatures. As endotherms, we have, and warm-blooded mammals, we have to make our own heat to maintain our body temperature. And if you look at, you know, a human or any mammal or any warm-blooded animal through an infrared camera, you can see the heat being emanated. And that is infrared light. So I think it's cool to think about it in that way that we're literally creating light. But we just don't think of it that way because we don't see it with our eyes. But heat in this context is light.

And so we have the infrared part of the spectrum. And then we move into the visible part of the spectrum, which is the Roy G. Biv. We have red, orange, yellow, green, blue, indigo, and violet. These are the visible wavelengths that we can see and is what constructs our reality. essentially. From there, we move back into non-visible light, which is the UV part of the spectrum. So UV is the beginning of the ionizing radiation part of the spectrum. UVA and UVB are what we receive from sunlight. UVC is the shortest wavelength, highest frequency part of the UV spectrum, but UVC is actually absorbed by the ozone layer in our atmosphere, and so it doesn't actually

reach the Earth. So UVA and UVB are primarily what we're receiving from the sun. And then we move up to x-rays and then gamma rays. So the x-rays and gamma rays are the canonical forms of ionizing radiation that we can encounter. But we're not encountering those from the sun. Like I mentioned before, those are kind of absorbed and or reflected by our atmosphere so that we're not affected by them when we didn't evolve to encounter these parts of the spectrum within our environments. And so the visible light spectrum spans from only 400 to 700 nanometers, and the rest of the light outside of those wavelength ranges are non-visible, and having said that, they can still be sensed by our bodies.

So light is light regardless of whether or not we can see it. And depending on the species that you are, like let's say you're an insect listening to this podcast, you have a different perception of reality entirely. You may be able to see UV light, for example, quite well and not being able to see other parts of the visible wavelength for us. And so the way that we perceive reality is very, very species dependent and species context dependent. And I think that's just something important to keep in mind whenever we're making scientific discoveries and claims within science, because everything is relative to our human senses. And so that means that the truths that we're uncovering are also relative truths. They're not absolute truths. Ultimately, our senses dictate how we, we are perceiving reality and therefore what our reality is to us.

And so that means we can only make claims about our reality as a human species, which, you know, I think is fine. There's nothing wrong with that, but we really need to realize the limitations of that if we're trying to make bold claims that are absolute about the nature of reality in general. Okay, so something that's important to talk about is the intensity of life. with regards to how it's affecting our biologies. And so light intensity, the sun was the primary source of light,

like we mentioned before, of light in our environments. And so the sun's intensity is quite high. So on a blue sky day, a clear day in the summer, you're looking at around 100,000 lux worth of light. Compare that to, kind of an overcast day, gray skies. You're looking at around 1,500 lux of light. And then compare that to like a full moon on a clear night. That's about one lux of light. So the sun is very,

very, very bright, which makes it a very intense stimulus for the entrainment of our master clock and in accordance all the rest of our clocks downstream. And having said, that at nighttime when we are supposed to be winding down and going to sleep, having lights on in our environment is sending the wrong messages to our body about the time of day that it is. So most well-lit indoor places are around 300 to 400 lux. And there's hard research showing that light that's even less than 200 lux in your environment before bed and during sleep is highly disruptive to melatonin release during sleep and your ability to actually get into good quality deep sleep and get also a healthy sleep duration. So lightness in the

environment is extremely important to consider when we're trying to optimize sleep and recovery and healthy circadian rhythm. In addition to light intensity, there's another metric that we need to consider and that is light temperature. So light temperature is a metric. that's measured in Kelvin. And light temperature basically tells you where on the spectrum of red to blue a given light source is. And so the lower the light, the lower the color temperature of a light, the more red that light is. And then the higher the color temperature of the light, the more blue that light is. And we know from, you know, extensive research studies that have been done, and I'm going to include some links to studies in the

show notes that both blue light and bright light will inhibit the release of melatonin from the pineal gland and this the release of melatonin occurs in accordance with declines in ambient light after sundowns so essentially if you keep bright lights on in your house as the sun is setting into the night time you are not releasing the melatonin that you need to actually get tired and get good quality sleep that night. And melatonin is actually really interesting. So it's a pleotropic molecule, which means that it has many different functions. It's derived from the amino acid tryptophan, which is an essential amino acid in humans.

It's also a very ancient molecule melatonin. So melatonin is found in bacteria, plants, and fungi. And it's the primary hormone that's secreted by the pineal gland in the brain. And so a lot of people don't realize that melatonin is a hormone because you can buy it over the counter and there's not really that much regulation on it. But the reality of it is is that it is a hormone and it does serve very, very important functions in the body and taking it exogenously is disruptive to the processes that require melatonin to be fully, you know, facilitated and actualized. But in addition, melatonin to inducing and sustaining sleep,

In addition to those things, it also enters the bloodstream where it entrains biological clocks throughout the body. And so in this way, the secretion of meltonin provides information to the rest of the body about, you know, it being nighttime, it being time for sleep and recovery. Interestingly, some non-sleep related functions of meltonin that a lot of people don't know about is that it's synthesized in the mitochondria of almost every cell of the body that contains mitochondria. So these include the GI tract immune cells and the liver. And in these cells, in these mitochondria, these meltonin pools don't freely exchange with the circulation. Instead, they remain in the tissue where they exert potent antioxidant and free radical scavenging effects. So melatonin has these kind of dual roles in both regulation of sleep and recovery and inducing of sleep, but also in anti-inflammation and free radical scavenging within tissues.

And so I mentioned this before, but the studies that I'm going to link here, there's one that basically shows that less than 200 locks of light around bedtime and during sleep dramatically suppress melatonin levels and shorten the body's perceived dark window. And this disruption of melatonin signaling has major implications, specifically in areas including sleep, thermoregulation, blood pressure regulation, and glucose metabolism, which are areas that we all really care about if we're thinking about optimizing health and leading a healthy life. And we also know from the research

that light exposure during sleep impairs cardiometabolic function. This is going to be one of the papers that I will include in the show notes, but moderate light exposure around 100 lucks in this case. after just one night time of exposure during sleep, this 100 bucks of light would increase resting heart rate, decrease heart rate variability, which is a metric for kind of how flexible your nervous system is and how well it is functioning. This 100 bucks of light also increased morning insulin resistance and increased oral glucose tolerance insulin levels. And what essentially that means is that it required more insulin to get glucose into muscle compared to people who were not exposed to light during sleep.

So now we've talked about the kind of the harms of getting artificial light before bed and during sleep. And I just want to emphasize that that's really important both for kind of bright lights that you might have in your environment and your home, but also for indicator lights that might be on video game consoles, light switches, like if you have any small indicator lights on any devices that are in your bedroom, please put like black electrical tape over them so that they're not shining any light when you have all the lights off and you're trying to go to sleep because even those small amounts of light can have an effect on your sleep quality. So it's very important to just get your room as dark as possible,

whether that, you know, means using the electrical tape on any indicator lights, making sure all your lights are turned off, using blackout curtains if you have windows in your room and if there's any ambient light exposure coming in from outside. Taking these steps to make your room as dark as possible while you're sleeping. It will make a big difference on your sleep quality and your recovery, and it's something that you can notice differences in immediately, like after one night of doing this. But on the flip side, in addition to the importance of dark at night, getting sunlight during the day, is also extremely important.

So there's a really cool review paper that is relating all the different health benefits of sunlight to a whole host of protective effects on health and the prevention of disease. And I really love this paper because societally today, we're really fed

this propaganda about the sun being toxic and something you have to protect yourself from. And yes, too much sunlight can, you know, give you burns and cause some issues. But our bodies and our species evolved to get sunlight. Sun is the primary source of the essential nutrient vitamin D, for example, just as an example that everybody kind of knows about. There are many correlations with low vitamin D levels and the development of certain diseases, specifically autoimmune diseases, seem to be tightly linked to. low vitamin D levels. In addition, melanoma is also associated with

low vitamin D levels, which is something that mainstream medicine has never been able to reconcile because there is this propaganda and this belief in the model that it's sun that's causing your skin cancer. Even though currently today, sunscreen use is an all-time high, indoor living is at an all-time high, and melanoma rates are at an all-time high. How can we reconciled these facts if sunlight is the cause of melanoma. It's, it doesn't make sense. So anyway, this paper that kind of shows I'm going to include it in the show notes as well, that sunlight confers health. Sunlight is associated with reductions in all cause mortality. It's associated with reductions in the rates of asthma, cancer, cardiovascular disease,

cognitive impairment, Crohn's disease, multiple sclerosis, Parkinson's disease, stroke and both type 1 and type 2 diabetes as examples. And so we discussed the sun was the primary source of light on the planet until very recently in our planet's kind of evolution. It's really only, it's been less than 200 years since we started having a lot of light exposure at night. And this is affecting not only us, but other species on the planet as well, especially those species that can detect the non-visible portions of our electrical.

electromagnetic spectrum. So insects, for example, who may be able to sense longer wavelengths of light in the infrared or even beyond that, radio wave out to what radio wave parts of the electromagnetic spectrum, you can imagine all of the light pollution they may be experiencing because of our just rapidly increasing use of technology. And there's this underlying assumption that I think is unwarranted, and that is that technology is assumed to be safe until it's not. Like, there's no rigorous testing of new forms of technology to show that they are safe for our biology and for our environments. Instead, these new forms of technology are instantiated, and then down the line, we do the research to show, oh, actually, there's all these negative effects.

Now we need to, like, re-engineer the technology so that we don't have these effects. when instead we should be doing that research up front to make sure that the products we're putting out are safe and that they're not going to be harming us unknowingly in 5, 10, 15 years, especially for devices like cell phones and wireless headsets that people are using from a very young age and they're using them for many hours a day. There's no safety studies to show that this isn't causing issues. And it's very concerning from a scientific standpoint that these types of questions aren't being asked because this is like a no-brainer when it comes to being scientifically rigorous,

especially if we care about the health of our population, we should want to know the answers to these questions. But I slightly digress. So I really just want to emphasize that, you know, Sun has held this very important role in our species development and the development of life on the planet. And the introduction of electricity around the world has completely subverted the evolutionary environmental constraints on light and dark cycles and the use of light and dark cycles to regulate biological processes. This is now being disrupted due to our interference with using technology essentially to create our own forms and sources of light. And so I mentioned before about the compact fluorescent bulbs having this kind of big peak within the blue and UV

parts of the spectrum. There's also a peak within the green and a small peak in orange. white LED bulbs also have a very big peak in blue, and they have some red to a lesser extent, though. And compare this with something like an incandescent bulb, which emits a lot of red and infrared light. And so the more red and infrared light a light source produces, and the less blue it produces, the less disruptive it is to melatonin production and release.

And so because of the big, peaks in the blue wavelength part of the spectrum in the LED bulbs and the fluorescent bulbs, this makes them highly damaging to the melatonin system. And so the research suggests that melatonin can be suppressed by up to 80% with the use of LED and compact fluorescent bulbs around bedtime and during sleep compared to incandescent bulbs, which only suppress melatonin production and release by about 40%. And then compare that with candlelight. And there's also Also, there's some O-L-E-Ds that are actually mimicking candlelight, and these will actually only suppress melatonin by about 2%. So if you're going to use light at night, you know, candles kind of romantic anyway.

If you're into aesthetics, I think it makes, you know, a lot of sense to maybe light some candles or get these O-L-L-D candlelight style bulbs that you can use around the house. There's also LED bulbs that you can connect to like your Wi-Fi and then change the color and the brightness from your phone. Those could also be a good option if you're trying to, you know, have some flexibility in your light environment throughout the day. You can turn them up brighter as needed, but just keep them down and more in a reddish hue later in the day to minimize the effect on sleep quality. So just taking a breather here really quick. We've covered a lot of information, and I'm sure that there's going to be lots of questions, so I would urge you to, if you're watching on YouTube, drop your questions in the comments. If you're watching or listening on Spotify, rather, you can drop some feedback there or any questions that you may have.

I'd also like to mention some research surrounding the use of blue blocking glasses for sleep and also for mood disorders. So there's a range of blue blocking glasses available on the market. the ones that actually work are going to have an orange tinted lens, as these are the ones that are really able to effectively filter blue light out of the ambient environment. And so if you buy blue blocking glasses that have kind of clear colorless lenses, they're only going to be blocking a very small fraction of blue light. I want to really emphasize the importance of getting a good quality brand

that is effectively blocking blue light. You'll know if it's working because if you look at any, sort of, let's say you have a blue indicator light on like your PS5, for example, you put the blue blockers on. That light will actually look gray. You really won't be able to see any blue emitting from that device at all. And I actually have a protocol that I'm, you know, I'm going to, for anybody listening to the podcast, I'm going to give it to you for free. So if you're interested in this foundational protocol that I created, it's related to all things optimizing your light environment and your circadian health. And if you're listening, you can shoot me a DM on Instagram and I will share it

with you. Or you can send me an email at Dr. Alexis Jasmine, J-A-Z-M-Y-N at gmail.com. And I would be happy to send it to you there. But anyway, so blue light blocking glasses, if they're a good pair, they will work extremely well to help improve your circadian health and your sleep quality if you wear them at night. And particularly in patients with any sleep disorders that are diagnosed, the blue blocking glasses can reduce sleep onset latency and help to induce the secretion of melatonin, which can help with deep sleep quality and overall sleep duration.

And these effects are also observed in individuals who do not suffer from a diagnosed sleep disorder. the use of blue blocking glasses also reduces mania in patients with bipolar disorder, which is really interesting. And I think as the research moves forward, we'll find that a lot of the psychological illnesses that we are dealing with today can have stems and roots back into circadian regulation and just kind of unhealthy environments in general. but specifically the light environment is one that's really the vast majority of people are doing it wrong because we've just normalized this very backwards way of living with regards to our light environments. And so it's something that's made such a huge impact in my life through optimizing these things and something that I'm really, really passionate about sharing with you guys.

And that's why this is the first episode, the first science episode that I'm really getting into with you because I really see this as the foundation upon which everything else is built. Because if your circadian health isn't optimized and your sleep quality is poor, you're not going to have the energy to go exercise, lift weights. You're not going to have the mental fortitude to make healthy choices with regards to nutrition. You're going to be way more likely to not be able to resist your cravings, to reach for the snack foods, to reach for the fast foods, to feel low energy and feel like you need. to consume more carbohydrates to boost your energy in the short term. You're also going to just give

into more cravings and bad behaviors in general because your willpower is going to be compromised just from having your poor quality sleep and recovery. And so I really see this, you know, as the foundation upon which you can build a healthy life if you really nail down these basics. And the best part of it is is that it's really easy to make most of these changes. It's also quite inexpensive. So in a lot of ways, it can be free depending on what you're willing to compromise on. And so that's another reason why I absolutely love focusing on circadian health and the light environment with clients. Because it's something that's so actionable, the results you get are almost immediate, and it costs very little money to do right.

Okay, now I want to focus on some of the benefits of specific. wavelengths of light within the sun. So depending on the position of the sun in the sky, we can leverage it for specific health benefits. Specifically, in the sunrise and sunset portions of the day, the sunlight is enriched in the red and infrared parts of the spectrum, this electromagnetic spectrum. And it's actually really interesting, but red and infrared light actually helped to support the skin to effectively assimilate UV light during the peak sun hours of the day around like solar noon. And we're going to get into why UV light is really important for health. But for now, I want to focus on the IR, the infrared and the red parts of the spectrum,

which actually help to prime your skin to accept that UV light midday. and what that means is it helps to support melanin production in response to UV exposure so that you're less likely to burn. In addition, red and infrared light is also anti-inflammatory so that if you do burn or have any sort of damage from excessive UV light exposure, that the red and infrared light can actually help to repair that and prevent any long-term damage. and there's actually a really cool study where they showed in patients in a lab, they irradiated their skin on little patches with UV light of different intensities. And then on the same person, they had a strip of skin where they exposed also UV light of different intensities to different spots, but they also preconditioned that skin with red and infrared light before the UV exposure.

And what they showed was that the same. skin burned significantly less on the skin that was preconditioned with red and infrared light before UV exposure. And this would be especially relevant for people who have like Fitzpatrick one or two type skin, which is very, very pale and very easy to burn. The red and infrared light would be particularly important to leverage for these anti-burning effects and the effective and supportive UV light assimilation. during midday sun. So independent of UV protection, red and infrared light also have other health benefits,

including improved tissue function, accelerated wound healing, anti-inflammation, and increased cellular energy metabolism. So red and infrared light can actually directly stimulate this complex of the electron transport chain in mitochondria called cytochrome Coxidase. And Cicrochrome C oxidase is kind of this crux in energy production within the mitochondria, that when you can activate it, you're actually going to make more energy, more ATP, in the cells.

So you're supporting the energy status of that cell without even putting food into the system, just with light alone, with this red and infrared light. So now let's talk about UV light, another really, really important portion of the sunlight spectrum. So despite having a bad reputation, UV light is absolutely essential for health.

And like I mentioned before, UV light falls into three categories, UVB and UVC, UVA and UVC. UVA and UVB are the ones that we're getting directly from sunlight, so those are the ones that I'm going to focus on here. UV light, because it's short wavelength, it doesn't really penetrate the body very much. It only penetrates into the epidermis of the skin. UVA light is the most abundant UV light in sunlight. And the exposure of skin to UV light, UVA light specifically, increases the expression of the enzyme called heem oxygenase 1.

that mediates antioxidant, anti-inflammatory, anti-apoptotic, and anti-prolifitive effects. So in this way, UVA light can be very protective against early malignancies, and also helps exert anti-inflammatory effects, you know, assuming that the dose is right. So the dose always makes the poison. If you're getting burned from sun exposure, you're overdoing it. And a lot of times, and I especially was bullish on this during the summer, but you have to develop something that like Dr. Jack Cruz calls a solar callus. So if you have very pale skin and it's kind of hard for you to tan, you want to gradually increase your sun exposure during midday over time. And

you also really want to leverage the red and infrared light either through getting a panel, like one from mito red that I have here. I have the mito pro series that's red in near infrared. You want to use something like that or you want to make sure that you're really diligently getting out and seeing the sunrise and sunset before you do. kind of any midday sun exposure if you have very pill skin. And you build up that solar callus over the course of days and weeks. And then ultimately, you'll be able to tolerate more sun without burning. But anyway, in addition, UVA also protects cells and tissues against oxidative stress and injury,

which can be induced with UVB exposure in isolation. So in this way, UVA kind of balances out the effects of UVB and together, we can really see that when we're encountering full spectrum sunlight, we're getting the medicine in its full spectrum form versus all of the studies that ever showed that UV light was harmful to, you know, causing malignancies such as skin cancer and that it's harmful to the eyes. All of those studies were done with UV light in isolation and none of them were conducted in response to or in the context of full spectrum sunlight,

which is absolutely such a mis-apportunity. at understanding really what's going on because our species encounters sun. It doesn't encounter UV light in isolation unless we're going to lay in a tanning bed, which is like a very small portion of the population. The fact that they extrapolated UV light as being harmful to that UV light

encountered in the sun is completely fallacious and kind of flies in the face of the data that suggests that the sun contains the portions of the light spectrum that are balancing to the negative parts such as UVB, which can be harsh in isolation, but has these very meaningful benefits in the context of full spectrum sunlight. The final thing I want to outline about UVA light is that it is a very potent stimulator of nitric oxide production in the skin. And that nitric oxide produced in the skin can permeate into the bloodstream where it directly promotes vasodialis.

blood pressure lowering and boosts athletic performance, cardiac health, and reduces erectile dysfunction for men. And so in this way, UVA light is really, really important for anybody who struggles with blood pressure regulation, anybody who struggles with any sort of vascular issues and heart disease. Like, it's really, really important for healthy circulatory function. And so I really emphasize in the foundational protocol getting a sufficient amount of sun daily especially during the months that you can get it. So in the northern hemisphere here, we're getting pretty great sun from like May to August, but after that, the intensity starts dropping down pretty precipitously. And we need to either get something like a vitamin D light

from a company like Spurdy or Chroma. They both make lights that contain UVB, which you kind of do in like a pulsatile fashion for a very short period of time just to get some of that stimulus in, but also if you can travel to somewhere, it has better light that's closer to the equator. That's also a feasible option during the off season, such as the winter and late fall and early spring. So with regards to UVB light, UVB light is the wavelength of light that's responsible for converting 7 dehydro cholesterol into pre-vitamin D3. So vitamin D is an essential fat-soluble vitamin and is ultimately a hormone. And it's essential for the function of the metabolic system, the immune system, skeletal muscle, and among others. Also, cognitive function.

And it seems like every day we have new functions that are being outlined for the role of vitamin D within the body. In addition to the roles in vitamin D synthesis, UVB also activates hypothalamic, paraventricular, and arcuate nucleus in the brain. rapid stimulatory effects in the brain. So it's a very potent stimulator of the nervous system. And that makes sense because the time that we would encounter UVB light in our environments is around midday when we're supposed to be the most alert. And through the activation of cellular defense pathways, UVB light triggers the transcription of this pro-hormone gene called pro-opio-melanacortin or Palm C. Palm C is a pro hormone that, depending on the tissue that it's produced in, has the ability to be

cleaved into up to 10 distinct hormonal products that regulate everything from energy expenditure to appetite, to pain relief, mood, and your ability to tan in response to sunlight. And so in this way, POMC is a very, very fundamental feature of regulation of biology, and its production is, its production necessitates exposure to UVB light, which we cannot get unless we are out in the sun. So with regards to vitamin D, a lot of people and clinicians will look at vitamin D

as something, you know, that you need to optimize as a standalone biomarker. So if you're deficient, you need to consume a vitamin D supplement and get your levels into an appropriate range. The way that I look at it, though, is that vitamin D is more like a biomarker for UV light exposure. And when we look at it in that way, we can really understand that supplementing vitamin D is actually just addressing a symptom and not a root cause. To effectively optimize our vitamin D levels, we actually need to optimize our sun exposure

and not merely just provide our bodies with a supplemental form of vitamin D to get levels to where we want them because then we're actually missing out on a lot of the other benefits of UV and sun exposure in general. But having said that, vitamin D, you know, does have mechanistic implications and immune function and muscle function. And a lot of clinicians will only diagnose you as low vitamin D if your levels are less than or equal to 20 nanograms per milliliter. But full suppression of parathyroid hormone, which is released when vitamin D is suboptimal,

occurs at levels of 25 hydroxy vitamin D, which is the storage form in the blood, of around 40 nanograms per milliliter or greater. So for this reason, greater than 40 nanograms per millimeter of vitamin D, if you're getting your blood taken, is ideal. And personally, I like to see vitamin D levels between 60 and 80 nanograms per milliliter. to really be optimal. And you're more likely to be deficient in vitamin D if you live in the northern latitudes, let's say above the 43rd north latitude.

And this likelihood will further increase if an individual has melanated skin. If you know you have darker skin like me, I need more sunlight to get the same amount of vitamin D as a very pale person. And also if you're overweight or obese, you have a higher likelihood of being deficient because vitamin D can basically be pulled out of the circulation and stored in a fat tissue where your body can actually access it. So if you're overweight or obese, it's really important to also make sure that you're getting in the sun, that you're optimizing your vitamin D levels.

And interestingly and importantly, the sun will also help you to lose fat and lose weight and optimize metabolism through that POMC molecule. So POMC creates this molecule called Alpha MSH. that is the most highly correlated marker, genetic marker, with obesity. And alpha MSH is really, really important for regulating appetite and energy expenditure in the body. And so the more pomacy you can create in response to the sun, the better regulated your appetite will be. And the more resting, your resting energy expenditure can be positively regulated to better support energy balance and, you know, any fat loss goals. With regards to vitamin D, it also plays really important roles in bone metabolism.

So one of the primary roles of vitamin D is to regulate calcium homeostasis in the body. So when vitamin D is sufficient, it facilitates calcium reabsorption to prevent calcium loss through the urine and the stool. And this calcium can then, you know, remain in the bloodstream, where in the presence of sufficient levels of vitamin K2, which you can get from fermented food, and organ meats, grass-fed organ meats and fattener cuts of meat, vitamin K2 allows that calcium to be taken up into the bones and the teeth. And so it's really important to kind of together, both optimize your vitamin D levels and make sure that you're eating a diet that's conducive to having adequate vitamin K2 levels to really get that calcium

to the places where it needs to be. Vitamin D actually also serves as a pretty reliable biomarker for overall mortality, hip fractures, and the development of muscle wasting or sarcopenia. And we've also seen in the literature that vitamin D status in deficient individuals, if you can improve their status, will improve metrics of mitochondrial density and mitochondrial functions. So in that way, it has very important links with metabolism as well. I mentioned the Fitzpatrick scale before, and that's really to help you decide how much sun you should get right off the bat. I really recommend the D-Minder app. It's an app where you plug in

your Fitzpatrick skin type, you plug in where you're located, and you essentially then input how much clothes you're wearing, and then when you go outside to get some sun, you can start a timer, and it will show you how much vitamin D you're making per minute, which is really cool. But for the Fitzpatrick scale, that goes from a type 1 up through type 6. Type 1 being very fair, which means that you almost always burn and can't tan. Compare that to type 6, which is dark brown skin that never burns and always tans. And then the types 2 through 5 are kind of the intermediate types. You can find the scale easily online and identify which type of skin you are so that if you go to use the D-Minder app,

you can input that information to get a better readout of how much vitamin D your making per unit time. Another thing I really want to mention about vitamin D is that vitamin D supplementation, and this actually goes very much along with the idea of vitamin D being a biomarker and less so a standalone metric to be optimized, is that vitamin D supplementation has largely resulted in underwhelming clinical benefits despite very strong correlations between vitamin D status and a variety of diseases. And I think this largely plays into the idea of, like I just a general.

just said, vitamin D being a biomarker for sun exposure and UV light exposure specifically, in addition to vitamin D having its own roles. And this can kind of be also exemplified by the fact that UVB exposure catalyzes the conversion of that 7-D hydrocholesterol into a variety of vitamin D-D-like molecules other than vitamin D3. These include tachystereal and lumestereal and their derivatives. So there are forms of vitamin D that can only be produced in response to sun that you cannot access by supplementing with vitamin D. So this just is another piece of evidence to show that it's really the sunlight and the UV light exposure that we need to optimize and less so just taking a vitamin D supplement to get that number where we think it needs to be. Now let's talk

about POMC a little bit. So I mentioned it before. Proopio Malinacortin is this complex prohormone whose production is stimulated by UV light. And it can be cleaved into 10 different hormonal products. So now I want to get into what those hormonal products are. So the first one is gamma MSH. Gamma MSH is a natueredic peptide that regulates blood pressure by modulating sodium balance. The second peptide is ACTH. This is a really important hormone that's made by the pituitary and it stimulates cortisol production.

And thus regulates hepatic glyphysh. glucose output. So I think whenever people hear cortisol, they think cortisol bad, which is just like such an oversimplification. Cortisol is an absolutely essential hormone for life. It is what basically turns your body on in the morning when you're getting up and getting ready for the day. It mobilizes blood sugar so that your brain can come online. Your nervous system can start firing and your body can wake up after being asleep and kind of dormant for so many hours during sleep. It's just when cortisol rhythms kind of get messed up due to unhealthy circadian rhythm or overly stressed states that you get these kind of sustained levels of cortisol that are

inappropriate. You're only supposed to get this moderate spike in cortisol in the morning about like roughly 20 minutes or so after waking up that can then come down pretty gradually and stay low throughout the day, but if you're extremely stressed or have an aberrant circadian rhythm, then those spikes, the spike in cortisol can either be shifted or can be extended. And that's where we run into issues with insulin resistance and just poor glucose control and just overall feeling kind of burned out. So then ACTH, that second peptide, can also be cleaved itself into a couple of different peptides. One is Alpha MSH.

So I mentioned this before, but Alpha MSH is what allows our skin to actually make pigmentation, to make melanin in response to the sun. But in addition to that, Alpha MSH also regulates inflammation and modulates the immune system. It regulates reproductive function and energy homeostasis by reducing food intake and increasing satiety. Alpha MSH also increases energy expenditure by increasing skeletal muscle fatty acid oxidative. And the second peptide that can be cleaved from ACTH is a peptide called CLIP, which is short for corticotropin-like intermediate peptide. And this peptide is an insulin secretagogue, so it helps your pancreas kind of create insulin. So this is particularly important for people who may have type 2 diabetes or type 1 diabetes, for that matter, who struggle to produce their own insulin.

the sun via Palm C, via clip, can help support insulin production in the pancreas. Another peptide produced from Palm C is called beta lipotropin, which is a pituitary peptide that promotes fat oxidation in the body. And then this beta lipotropin can be further cleaved into three different molecules that are very interesting. And these are beta endorphin, which is the primary endogenous opioid within the body. that's highly anxiolytic and has this very potent mood boosting effect. And beta endorphine can also be claved into two other forms of endorphine, gamma, gamma endorphin, so gamma

endorphine creates a relaxed antipsychotic effect and it also helps to regulate blood pressure. Versus alpha endorphine creates a more amphetamine-like neurological effect, which is like more stimulation and more focused and also stimulatory to the immune system. Finally, the last two peptides that are produced in response to palm C cleavage are gamma lipotropin, which also promotes fatty acid oxidation and lipolisis, as well as beta MSH, which regulates feeding behavior, appetite, and hypothalamic control of body weight. So another really important one with regards to energy balance and maintaining a healthy body composition. And I mentioned before that depending on the tissue that the pomacy is produced in, it's going to dictate how many of these different peptide

products are produced. So when light hits your eye, including UV light, and that signal is transduced to the brain, we get POMC production in the anterior lobe of the pituitary, we get it in the hypothalamus, and we get it in the PARs intermediary of the pituitary. So all the parts of the brain that can make POMC are going to be making POMC in response to UV light hitting the eye and that signal being transduced into the brain. And this is really important to recognize and consider because if you're wearing sunglasses, if you're wearing prescription glasses like these, if you're wearing contact lenses, you are blocking UV light from entering your eye and sending that signal to your brain. And as a result, you're not getting the POMSI production stimuli needed

to actually facilitate the benefits of this multifactorial and like cleotropic molecule. So to get the improved satiety and the increased energy expenditure and all the metabolic benefits of palm C expression in the brain centrally, we need to have UV light entering our eye for a period of time during the day. And that means not blocking it out actively. And in addition to that, the other place that Palm C is primarily made is in the skin. And when it's made in the skin, we're getting full cleavage into the 10 cleavage products. So really important to also expose the skin to the sun. And we already talked about why that's important from a vitamin D standpoint.

But for POMC, it's also really important. Also worth noting that the skin of the abdomen, there's neurons under it that are major POMC producers. And so if you can expose the skin of your abdomen in particular to the sun, you can get the maximum amount of benefits that you can get with regards to Palm C. So really the prescription is to get outside, don't wear glasses, sunglasses, contacts, expose your belly, lay out for a period of time that's dictated by a combination of, you know, your own intuition on how you're feeling in your body if you feel like you're burning or not, the time of the year.

You know, if you want to use your deminder app to help you decide that as well, that's totally fine. but just making sure you're getting out there midday. And we also talked about earlier that getting outside in the morning, and maybe we didn't say this directly, but I want to say it directly now, getting natural light into your eyes first thing when you wake up is extremely important for entraining that circadian clock in your brain, the SCN. Your body needs to know what time it is, and the only way it can do that is by integrating natural light from your environment

because that's the light that our bodies were designed and involved to interpret. And so even if it's only for two to five minutes, get outside. If you can get your bare feet on the grass or even concrete, even better while you're getting sunlight into your eyes, because that can facilitate earthing and grounding, which gives your body free electrons to use, which electrons are really what we make energy from in our bodies. So if you can do that, great, getting your bare feet on the ground, getting sunlight in your for two to five minutes. If you can stay out longer, great.

If not, it's okay. You're going to still get massive benefits from even that short period of time. We've covered so much in this episode. I don't even remember when I started, so I don't know how long we've been going. But I think we're going to call it here. I think I have even more to say on these topics.

But I think this was a really good beginning overview of what's important and should give you guys plenty of information to digest with regards to circadian health and the light environment. So I really urge you to take some notes

while you're listening to this to also check out the show notes. If you can, you can look at some of the papers that I referenced. You can check them out for yourself. If you need to go back and listen again to take notes, that would be great.

If you have questions or, you know, ideas or want me to explain or expand on anything I spoke on, drop a comment on YouTube or Spotify. And if you enjoyed it, you know, also leave a comment if you can, leave a rating. It would be super helpful to kind of gain some momentum here early on. But other than that, reach out to me if you want access to the foundational protocol, which outlines all of the circadian and light environment recommendations to optimize your health in this capacity.

I really want to share it with as many people as possible. I think this work is extremely important. And it's also very actionable and accessible. So please reach out if you or anybody you know or love would like to have access to it. I want to share it with as many as possible. So I hope you enjoyed this episode. Looking forward to hearing your feedback on it. And I hope everybody has a great day.

I'll be back soon with another episode. Haven't decided on the topic yet. but I think it will probably be another solo episode and then we'll dive into some interviews so stay tuned for that hit the subscribe button over on Spotify or YouTube if you want to stay tuned and not miss those episodes and looking forward to chatting with you guys again soon