We’ve Been Wrong About Sunlight... It’s Not Just Vitamin D | Dr. Roger Seheult

0:00 We're spending so much time inside. We have windows that block infrared light because we don't want to increase our cooling cost. We have replaced all of the lights in our homes with LED bulbs. What Bob Fosbury calls this is the scurvy of the 21st century. I know this sounds like wishful thinking, like you just need to get outside in the sun, but yet what do we see on those British ships? Drink this ration of lime juice. Your sailors, your colleagues will stop dying. It's that simple. We have created an environment that is completely bereft of the same wavelength of light that the sun is giving us the majority of and it is also very beneficial for just about every cell in our body. I believe that incandescent bulbs are better than just narrow band LED red light or infrared light therapy. LED lights are not as

0:46 effective as diverse multi-wavelength light that we would see either from an incandescent bulb or from the sun itself. much better results versus just one particular color of red light. 50 years ago, you would easily hear from the scientific community, the only real benefits for going outside in the sun is getting your vitamin D. That's the only thing that we knew. The sun is way more than just vitamin D. Dr. Well, for somebody right now hasn't tuned into the importance of their light environment, let's give them the 101 on why this is something that is so critical and what it's doing to their health. >> Yeah, very good point. I think I think the best way to start out is to look at the ultimate source of light in our world, which is the sun, and the three

1:32 types of light that come from the sun and what they do to the body. because all all three types of light are very important to the human body. Um the first one we all know about this and that's when we go outside and we say we're getting our vitamin D and that's because ultraviolet which is a form of light that we cannot see from the sun it's it's so high in in wave in um frequency that it uh it's it's beyond our ability to see it but it's there and it uh it it when it hits the skin it takes cholesterol derivatives in our skin and turns it into vitamin D. So that's really important. Vitamin D has many uh attributes to it. Not only bone, calcium metabolism, but also immunity, things of that nature. So, uh that's one of the benefits of of going out in the

2:18 sun and having appropriate light. The other is visible light. So, this is the the light that you can see with the naked eye. Uh red, orange, yellow, green, blue, indigo, violet. Uh we could get into a talk there about how certain colors actually affect our brain. uh very good research going on right now at University of Arizona uh where that's being um looked at. Uh for instance, I'll give you an example. Green light and blue light, the colors of green and blue actually have a an effect on our our our perception of pain. It actually reduces our perception of pain. Maybe the reason why we notice that people that get outside have less need for pain medications in the acute pain setting. They've actually done studies on this, but it it's much more than just color. So light itself going into the eyes is

3:06 one of the major zeitgeabs or aectors of the uh clock that runs in your brain that runs all the systems. Um and this is I can't I can't really understate this. This is so really important for your entire body how important this is. To give you an example uh if you if you take Disneyland for instance you know that uh during the day there are operations that are going on there are rides that are going on the gift shop all this stuff. But at night, every all of that shuts down and there's literally an army of people of employees that go in at night to get the park ready for the next day. Engineers that shut down the rides and check for fractures in the in the metal. Um the gift shop that gets restocked, the gardeners that weed the gardens, uh the people that take the gum off of the off the pathways. And so when

3:54 Disneyland opens at 8:00 in the morning, the whole crew that's worked on it the whole night, it's like a brand new park. and and the the human body is far more complicated than Disneyland. And as as a result of that, you can imagine all the systems that are in place. There are systems that are are functioning during the day that incorporate molecules to make things uh food that you're eating. And then at night, the opposite happens. Things get broken down, things are being repaired. Um and all of those genes are coordinated by your your circadian rhythm. So what is the major input that determines that circadian rhythm and its effect? It's light. uh light going into the eyes there's also an effect of mood. So light coming into the eyes also affects mood especially in the morning time. This is the reason why people especially women who live at high

4:39 latitudes uh are susceptible to getting seasonal affective disorder which is a condition where they're depressed. They're not seeing enough sunlight. This typically happens in the wintertime, hence the term seasonal affective disorder. So that that's a whole talk right there. Um and then the the last type of light that comes from the sun is actually the majority of the photons that come from the sun. More than 50% of those photons that come from the sun are in the infrared spectrum. This is very long wavelength, very easy to penetrate through things very easily, the atmosphere, um uh your your your clothes, your skin. In fact, there was a recent study that was just published uh in uh from London uh University uh College London, Glen Jeff group that they actually measured infrared rays

5:26 going through someone's body um and coming out the other side. And not only that, but that lab has also done great work in showing the effects of infrared light on the cells, specifically the mitochondria, the the engines of your cells and how it upregulates energy production, which is really uh the antithesis of what we see with aging. So um and this is infrared light and and there's multiple randomized control trials which now show that this type of light infrared light has a tremendous benefit on health not only in the long-term setting but also in the acute setting. There's a paper that was just published this year or actually in 2025 that showed that uh medical intensive care and surgical intensive care patients both that are exposed to this type of light leave the intensive care

6:12 unit 30% faster and are stronger than those that uh get placebo. So um to review we have ultraviolet light vitamin D very important there. We have visible light super important in terms of our circadian health and mood. Uh can't understate that. Um, also darkness is really important for circadian health. So having light at the right time of day and having darkness at the right time of day. And then finally, infrared light, which increasingly more and more we're becoming devoid of that in our environment where we have LED lights in our homes. We have windows that block infrared light. We spend 93% of our time inside. Um, so really this is a huge topic. There's multiple uh um aectors of light on the human body and there's many places to dig in.

6:58 >> Well, that was a great overview. I think taking time now and getting into each of these more in depth is a good way to structure things. Coming back to UV, which is the first one you went over there. This is not visible. You mentioned the connection there to vitamin D. Let's talk about in a practical sense what it looks like getting the UV light in a healthy way. >> Yeah. So, you really have to be outside to get that because um ultraviolet light even though it's very high frequency and high energy, it does not penetrate very well through objects uh through clothes. So, you have to be somewhat exposed and and because it cannot penetrate very easily. Um the sun has to be pretty high in the sky for you to get enough ultraviolet radiation. So, winter time is not a good time to get uh ultraviolet

7:45 light. That's why a lot of people supplement with vitamin D. But um there's there's actually more to ultraviolet light than just vitamin D. We we did say vitamin D with ultraviolet light, but there's something called nitric oxide which also is released from uh exposure to ultraviolet light. There was a study that was done in fact um looking at blood pressure and latitude. This is this was prior to 1980 when we started developing very effective blood pressure medications and this study was done looking at the entire globe and measuring people's blood pressure in various countries and measuring the distances from the equator and what they saw was very clear. It was subtle but it was very clear and statistically

8:31 significant. The further someone lived from the equator the higher their blood pressure was. And um and we've we've shown this Richard Weller uh he's a dermatologist at University of Edinburgh in Scotland. Uh he was actually on this paper and uh he's shown he was one of the first to show that ultraviolet light exposure to the skin creates a molecule called nitric oxide. And nitric oxide is a second messenger system uh aector in the cell which which basically means that it it is is telling the the systems in your body the vascule in your body to relax. And so when the blood vessels relax when they open up now the pipes are bigger and the pressure inside those

9:18 pipes are relieved and the pressure comes down. Well, this type of light is more abundant at the equator and uh there's about a 5 to 7 mm difference when you go from the equator to the highest latitudes in that study. So, and by the way, not only going north but also going south away from the equator, they also noted the same thing. So, um vitamin D is a uh is a steroid hormone. That's important to understand because steroid hormones circulate throughout the body and they're able to penetrate through the cell surface and actually go into the nucleus of the cell where they are able to interact with transcription and DNA reading to make messenger RNAs and messenger RNAs of course are what um

10:03 is the code for protein synthesis in your cells. So the the the reach here is very very wide. what we see with ultraviolet light uh multiple benefits. So, how do you get this ultraviolet light? Well, you've got to be outside and the sun has to be pretty high up in the sky. Um the uh the uh the darker your skin is, the more time outside you have to be to get this ultraviolet radiation because the melanin, not the melatonin, but the melanin in your skin actually blocks ultraviolet light. So, if you are very fair skinned and uh a Fitzpatrick, in other words, there's different Fitzpatrick types of skin. One is the is the most whitest and you know, six I believe is is the most darkest. If you're uh one of those higher levels,

10:50 you could get outside and get quickly um your daily dose of ultraviolet radiation. Um if you're not, if you're um if your skin is is darker in color, you've got to be out there for much longer. Think about this. Um, I think we can all agree that the human race probably originated somewhere around Mesopotamia or or Africa, somewhere close to the equator. And they were very likely dark-kinned people. Um, as they moved away from the equator, think about what what happened here in terms of adaptation. As they as these groups of people moved away from the equator and moved into Europe or even Northern Europe, the body's need for ultraviolet radiation was so constant, so powerful that it actually that those

11:37 those societies actually became lighter skinned because the availability of ultraviolet radiation at those latitudes was diminished enough that there had to be adaptions, adaptations that the human race had to have in order to remain a viable race at those latitudes. In other words, their skin had to become more and more uh pale. Um if you think about it the other way as as you're going down to Australia, it's kind of an aberration there. Uh is that um there's quite a lot of ultraviolet light down in Australia even though they are quite far away from the equator. And that has to do with the ozone layer and ozone blocking ultraviolet radiation. So there's uh there's a posity or a lack of of ozone uh around Australia around the south pole. Um and as a result of that uh much

12:24 more ultraviolet light comes in. Look at the people indigenous to Australia uh very far away from the equator as opposed to northern Europe. The northern Europeans very light-skinned traditionally who are the who are the aboriges of Australia still very dark-kinned interestingly. And I and I think as a result of that, we can kind of conclude maybe anthropologically that Australia's always had quite a bit of ultraviolet light. Now, what you do is you you put people who are light- skinned in an area where there's a lot of ultraviolet light and you're going to get a lot of of of burning of the skin. Conversely, you take people who are darker skinned and you put them away from the equator where they already have a sort of a built-in mechanism to protect themselves from the abundance of ultraviolet radiation which they're used to getting at the equator. And you put

13:11 them in an environment where they're not getting enough ultraviolet light cuz they're not outside long enough. And now you introduce to them, you know, the modernities of of all of these technological advances like being indoors, air conditioning. Um, you can see very quickly how uh and it's easy to understand why so many people at these latitudes can be uh very deficient in vitamin D. >> Okay. You're making it very clear early on, which I think is critical, that when it comes to light, it's not just vitamin D. Because I think that can actually be a detriment to a lot of people who see it that way and figure, okay, this is getting complicated, different types of light, different, you know, latitudes, skin colors. I'm just going to take vitamin D and be done with this.

13:56 >> So, you're making it clear vitamin D. >> I know you're somebody that does take it. You feel it's important. It's a piece of this, but it's just a small piece of the whole picture here. >> Vitamin D is necessary, but it's not sufficient. I think that sums up uh what we're talking about and it's going to become even more clear when we start talking about infrared light which is on the other extreme of that visible spectrum. Absolutely. Okay, let's stick with UV right now and I want to make sure before we leave this part we're clear with people the goal here because again with the variables skin color, latitude and even time of day is going to influence heavily the amount of UV. How does somebody know if they're getting enough? And let's start near the equator to eliminate that variable. And

14:41 then I want to talk to the person like me. We were talking before the call. I'm in Ontario and we're in the middle of winter right now. What can I do by getting outside or hacking that to make sure I'm getting enough of this UV light? >> Yeah. And UV is is an interesting um aspect because there there are certainly beneficial effects to ultraviolet radiation. Um but there's also detrimental effects to ultraviolet radiation when used um in uh in the absence of the other types of light. So when used alone, we have uh evidence at least on petri dishes and in labs that ultraviolet radiation because it is so high in energy can actually cause mutations in the DNA and that leads to cancers. So there's this concern about

15:28 skin cancers. There's a concern about melanoma. Um, interestingly, there's a a paper that just uh hit pre-print, which is Richard Weller's uh paper looking at uh a UK bioank 400,000 large study where they looked at ultraviolet light and they and the differences at least in England at that latitude and what happened to people who had a lot of exposure to ultraviolet light and people who didn't have a lot of exposure. And basically what they found was that if everybody in the cohort in the group that they studied 400,000 UK bioank if everybody had gotten the least amount of ultraviolet light in that cohort okay as opposed to being distributed if everybody did exactly what everyone did

16:14 to get the least amount of ultraviolet light. There would be about 30 or 40 less melanoma deaths over about 8 to 10 years. But there would be probably 2 or 3 thousand more all-c cause uh deaths. Okay. On the other hand, if they were to have made everybody have the highest exposure of ultraviolet light in that cohort, then uh there would be about 30 or 40 less uh sorry, more melanoma deaths and and skin cancer deaths. Um but there would be up to 3 to 4,000 less all-caused mortality, so non-skin cancer deaths. And so there's kind of a trade-off. And so your question is is how do you in Ontario get enough ultraviolet light or anybody around the

17:00 world get enough ultraviolet light especially in the winter time? Uh number one, I would highly recommend getting outside for as as much as possible and there'll be reasons why we talk about that later. But for ultraviolet purposes, even on days where you where the sun is not high enough to get ultraviolet light, let me tell you there's a a astrophysicist by the name of Bob Fosbury who believes that something called relay scattering which is the reason why the sky is blue because it takes that area of the spectrum and scatters it across the across the sky across the canopy that you can actually get the right amount of ultraviolet B radiation from the sky even though the sun itself is not high enough. So there there seems to be some

17:45 evidence that you can get enough ultraviolet light even in the dead of winter by going outside if there is blue sky. Uh obviously the clouds would block that. But if there's blue sky in the middle of the winter time, getting outside. Now of course that ultraviolet's going to have to hit your skin somewhere. So if you're completely bundled up and only your face is showing, you're probably not going to get enough. Uh going back to that, uh I would say supplement. Now the question is how much do you supplement? Um it's it's really difficult to tell because the amount of vitamin D that somebody needs to take in to get to a specific level is dependent on their age. Um it's dependent on their body mass index. The more the older you are, the more vitamin D you need. The larger you are, the more

18:31 vitamin D that you need. And uh and uh uh also there are other extenduating circumstances as well. For instance, there's some studies at least in animals that indicate that high intake of high fructose corn syrup can actually inactivate vitamin D, turn it into the 2425 version of of vitamin D as opposed to the 125 which is the active form. So all that to say is is that uh if you are concerned about your vitamin D levels because either you're you're you have darker skin and you live at higher latitudes, I would highly recommend consider supplementing with vitamin D. But I would even more highly recommend that you get your levels tested and make sure that you're at the appropriate level once you get on a certain amount of vitamin D. There's some people that

19:16 supplement with vitamin D in the winter time only and they don't do it in the summer because they're outside enough. I think that's a reasonable way of doing it. The other thing I would just mention before uh leaving vitamin D is that vitamin D is a fat soluble vitamin which means it's possible for you to collect enough vitamin D in the summertime and then have it stored at least for some use as you go into the winter time and and use your body store. So it doesn't uh it's not something that you need to take on a daily basis. In fact, some people administer vitamin D monthly because it is fat soluble. So anyway, those are some thoughts. That's a point I wanted you to hit on there. The fact that the seasonality, especially in a place like Ontario, maybe that's just a normal response for

20:03 the body to get different amounts of vitamin D and different amounts of sun as inputs in different times of the year. >> Yeah. So, you mentioned vitamin D supplementation being a little bit different depending on variables for each person. What's the goal level you like to see with your patients? Yeah, that's a good question. Um, so there's first of all, let's talk about the units. Uh, nanograms per deciliter, I believe, is the one that I use. It's sort of the lower one. It's the one that we use in the United States. There's the one in in uh Europe, I think, is milliliters uh sorry, millim moles. Um anyway, uh the one that I use is the nanogs. And for that, generally speaking, you'll see on the lab results

20:48 that come back that they like that to be above 20 or 30. And that's been validated for bone. And I think that's probably realistic. I personally like to see in my myself and also my patients a higher level. And it's only because of what I saw during CO where we correlated very well with vitamin D levels less than 50. As as vitamin D levels started to come down less than 50, that's when we started to see an increase in the incidence of CO 19 infections. So I don't believe that there's been a value that's been validated against infections or acute chest infections. I know that Martino did a a metaanalysis that was published

21:34 in the British Medical Journal a number of years ago that showed that supplementation with vitamin D actually reduced uh acute chest infections. Um I'm not sure if he actually came up with a level where that seemed to uh be validated, but the level that I aim for is about 50. I think that's a reasonable level. And so um I've I take supplemental vitamin D. I take about 4,000 units internationally daily. That's enough for me in my my body at my latitude and my skin color to keep my levels at about 50. But everybody should everybody's different and there is no magic dose. Um and so I would highly recommend that people get their levels checked because it may be too low or more rarely it could also be too high. Uh there are a few case reports of

22:20 vitamin D toxicity. So it is possible. I would I would just be careful and get your levels checked. A lot of times with vitamin D, you see K2 being part of that supplement as a package. Do you think that's critical? There are some studies that seem to indicate that vitamin K2. Now, this is not to be confused with vitamin K, which is obviously involved in anti-coagulation and it's an uh antagonist to cumin. So, this is K2. It's a little different. Um that it it prevents the deposition of calcium in the blood vessels. So, uh, yeah, I have no problem, uh, with people taking vitamin K2 with the with the D as well. As of late, I've been hearing this talk when it comes to vitamin D that it's actually used in rat poison. And there's a group of people, it seems to be

23:06 gaining momentum, that are saying vitamin D supplementation is toxic and to avoid it. Have you heard this? Yeah. I mean, in France, uh, back in the, uh, the Von D war of the 1790s, they used to drown people in water, and that's how they kill people. Does that mean that water is, uh, is dangerous and we shouldn't drink it? I mean, uh, yeah, the rat poisons got high levels of vitamin D on purpose so that it's toxic, but just about any I can't think of a single substance that we take into our body that if given at high doses wouldn't also be just as lethal. So, um, yeah, it's, uh, I don't think that taking appropriate doses of vitamin D is toxic or or lethal in any in any way

23:52 because that same argument could be used for just about any other uh thing. We could I could give people too much water. In fact, a woman um I I use the France thing a little bit kind of tongue and cheek, but there was a radio station that put on a promotion to see who could drink the most amount of water. And this poor lady did win, but she she died because of she dropped her sodium too low because she drank too much water. Her brain swelled and she seized and died. So, uh, something as nutritious as water can also be taken to an extreme. Good point. Have you heard of these spurty lamps or other brands or similar lights that can be used indoors, especially somebody like me in the winter time to synthesize some of what we'd get from sunlight? I think we're getting better and better at that. Um

24:39 I I I I really have this philosophical problem with medical reductionism where we try to find something that's good. We try to distill it down to its functional parts, isolate it, concentrate it and then give it uh because when we do that, we take it out of its environment that it was placed in and there may be actual beneficial associations with other factors around it that we may not understand. Uh the case in point of that is the studies where we looked at lung cancer patients who had diets that were high in vitamin A and vitamin E, you know, um uh those types of substances. And so what we did was we uh took we ran trials where we gave high doses of vitamin A, vitamin E, uh betaarotene to uh lung cancer patients. They had to

25:25 stop that study early because they found that those substances and high doses given away from the uh environment that they were normally in actually caused worse deaths. Um and so uh this this idea of medical reductionism where we find the the magic particle, package it and then patent it and then sell it. Um, I think it's it's never as good as the original. >> Earlier you talked about cancer and how balance is key. Not getting too much light, not getting not enough. >> Yeah. >> Let's bring sunscreen in and talk about people using that. Is there a healthy way to use that? Are there healthy sunscreens? >> Yeah. Your thoughts in that realm? >> Yeah. So, what what is sunscreen doing? It's the the purpose of most sunscreens,

26:10 although there are some sunscreens out there that actually want to block infrared light. I have no idea why they would ever want to do that. Uh, but most sunscreens are there to block ultraviolet light. You can block ultraviolet light with clothes. Generally speaking, one one or even two layers of clothing is plenty to block ultraviolet light. Um, what I think people want though is they they apply this sunscreen because they want to get out in the sun without the benefit of or without the detriment of having clothes on because they want a sun tan. They want to be tanned. So there if you if you look at the way they test sunlight, let's talk about efficacy of sunscreen or sunblock. It's it has to be constantly be reapplied. It has to be on. It cannot be washed off. And that is

26:55 the only way you can reach some of these SPFs that are published on these sunscreens. There's a big there's a big scandal going on right now in Australia. Uh because of the amount of melanoma cases, the government has actually kind of opened up and and asked for products to be made so that people can get these sunscreen products. And what they found is that many of these products that are coming to market are not standing up to not even a tenth of what is published on the uh on the on the bottles. So the the other effect of sunscreen is this uh psychological problem um where you are psychologically think that you're protected. So, you put the sunscreen on, you've applied it, you haven't reapplied it, you didn't apply it properly, and

27:42 now because you think that you're protected, you're going to spend more time out in the sun, and actually u you might even lead to more skin damage. The other effect of this is the chemicals that they put in the thing. Have we actually tested uh these chemicals and how they get uh uptaken into the body, what their effect is on the body in the long term? You know, we we don't know a lot of these things because we haven't looked for these things. But we know that chemicals can be absorbed through the skin. We that's why we make medicines that are patches, right? Lidocaine patches, fentinel patches, we know that the skin absorbs chemicals. Uh and uh certainly that's no different with sunscreen. So, uh, I think if you're if you're trying to protect yourself from excessive ultraviolet radiation from the sun, which I think is

28:28 perfectly appropriate, especially in people who live in environments where there's a lot of ultraviolet light and they have sensitive skin, then uh probably the one of the most effective ways of doing that is to cover up and to to wear a broad rimmed hat, to wear a long sleeve uh shirt, to go outside but not necessarily in direct sunlight, or to avoid direct sunlight between the hours of 10:00 uh a.m. and 2:00 p.m. or even 4:00 p.m. and then go out in the morning when the sun is coming up which has a lot of other benefits which we'll talk about or when the sun is setting when the suns are when the sun is at the the the rising aspect of the day and the setting aspect of the day because it has to go through so much atmosphere to get to your eyes and to your body. There's

29:13 really a minimal amount of ultraviolet radiation occurring at that time of day. >> One thing you've hit on a couple times I want to highlight is with UV light, it doesn't go through the clothing versus what we're going to get into later with infrared where we can still get our dose being clothed outside. >> Yeah. Before we part ways on the UV part, just to round everything off here, again, coming back to me in Ontario in the winter, we know it has to hit the skin to get the UV benefit. What is my best bet? obviously exposing as much skin as possible being out midday, but for me to get as a Caucasian light skin, what would I need to do throughout the

30:00 winter to get a healthy dose of UV? So, some people would say that right now in Ontario in the wintertime, the sun is not high enough to produce vitamin D in your body. And uh I would say that that's probably true based on the the height of the sun. Again, there is some disagreement in the scientific literature that you may be getting enough vitamin D through ultraviolet radiation through relay scattering from the sky. But um let me just sort of reflect back. There was a study that was done um I believe it was Richard Weller again uh on this study looking at CO 19 mortality and they specifically looked in the portion of the United States in the wintertime that was above let's say Tennessee uh roughly speaking where

30:46 there was no way you could get enough ultraviolet radiation similar to Ontario where you could not get enough ultraviolet radiation to make vitamin D even in those at that time and even in those places they were able to statistically show that the more sunlight that people had, the lower the CO 19 deaths were. And this was in a a paper that was published um not only looking at the United States, but they validated in Great Britain and they also validated in Italy where in the wintertime not enough uh vitamin D being produced they thought, but still a benefit from a correlation with more sunlight. So to get back to your question, there's actually nomograms that have been published that that show

31:32 like if this is the time of year and this is your latitude, this is how much time you need to spend outside in the sun to get enough vitamin D in your system. And I don't have that in front of me at the moment. I can look it up. It's it's been a while since that's been published. But the the the I remember looking at it and seeing that the longest amount of time that it it took it generally was around 5 to 15 to 20 minutes to about 30 minutes generally speaking. But obviously in the winter time in Ontario in Canada you're going to be 30 minutes plus to get enough of that light if you're going to get enough vitamin D. And we also want to always come back to the thesis here where vitamin D is important, could potentially be a proxy for other things, but we know with

32:19 UV specifically, there is N O and there's probably a lot of things in our lifetime we won't even discover that UV is doing to the body. >> Yeah. Exactly. So that that's I mean if we were to go 50 years ago, you would easily hear from the scientific community, oh the the only real benefits for going outside in the sun is getting your vitamin D. And that's because that's the only thing that we knew. We don't know what you don't know. And what we've discovered, especially in the last year or two, uh the science on this has really exploded and we're finding out that the sun is way more than just vitamin D. >> All right, let's pivot into visible light now. first thing in the morning. We'll go right through the day. When and what is the ideal exposure and why? We're talking about visible

33:06 light now. And because we're talking about visible light, we're talking about light's interaction with photo receptors in the back of your eye. Now, these receptors are called intrinsically photosensitive retinal ganglen cells. So, if we ever use that term, you'll know what they're talking about. These are not the rods and the cones that let you see specifically. These are general like light sensors kind of like very similar to the sensor that you might have on an outdoor light that you have it set to come on when the when the sun goes down. Uh that's the type of light sensor that we're talking about. So is there light? Is there not light? And and that sort of thing. Now these these sensors tend to be on the lower portion of your retina and as a result of that they are more stimulated by light in the upper visual aspect of your um of your

33:53 visual uh system and that's simply because the image gets flipped. So if you have an image in the upper portion like the sun where the sun is uh where the sky is that is going to project to the lower portion of your retina which is where these retinal ganglen cells are. Now these retinal ganglen cells have two projections. One projects to the the timekeeper of your brain and of your body called the supercaismatic nucleus and the other projection is to an area called the perihabenular nucleus in the brain and this is where mood is regulated. So the two major consequences of getting outside and getting light into your eyes is not only get getting your circadian rhythm all matched up but

34:39 also getting the appropriate mood. Now this is really important to understand because this affects so many things in your in your body. So let's talk first about the circadian rhythm. Getting outside into bright light is going to keep your circadian rhythm on a clock and making sure that your schedule is on time. So many studies have shown that when people's sleep schedules change or they're not uh grounded uh at the particular time of the day, that's what increases cardiovascular risk. That's what increases uh cancer risk. And the reason for that is because you're not coordinating the as the different aspects of your body all at the same time. Um, think

35:26 about the Disneyland uh thing again, right? If you've got the engineers out there shutting down the ride, but you don't have uh the other people to inspect the ride, if they're not coming in at the same time, you're not going to get the full benefit of that team showing up to look at those to look at Space Mountain, for instance. If you're not getting the the guy who washes the street at the same time as the guy who scrapes the gum off the ground and if they're not coming at the same time because they're not coordinated, you're not going to get the maximum benefit of those two groups of things that are probably regulated by different genes coming on at the same time. So what you in fact you get is you get a half job get getting done when your clock is not in sync. And so as a result of that, it doesn't it's it's not too hard to understand why cancer rates would go up,

36:12 cardiovascular rates are going up. The reason is is because to keep your cardiovascular disease rates low, to keep your cancer rates low, multiple systems in your body need to be working in concert with each other to do the job correctly. And when the clock is not being set appropriately, those things are not being coordinated. And so you're not going to get the same kind of job. So, one of the things that really entrains your clock to make sure that it's on time and everything's running on at the same time is bright light in the morning. And I would say before 9:00, how do you get that bright light? You need to go outside. I I can't say this enough. If you think that you're getting light enough inside your home, let me let me disabuse you of that understanding because if you were to

36:59 measure the amount of light in a typical room inside your home in the morning, you would hit maybe about 100 lux. A lux is how we measure the intensity of light. At the same time, if you were to go outside, it would be if if the sun sun was shining, it could be up to 100,000 lux. So, you're getting a thousand times more light outside than you're getting inside. And and because of that, the dose needed is going to come a thousand times faster outside than it would be if you're inside. You people, anybody who who is in photography would understand this. If you set up a a manual SLR camera inside to take a photograph and you you set the f-stop and the ISO and the aperture rating, all those things just for the perfect picture, and then take that

37:45 camera, don't change anything, and go outside and try to take a picture. It's just going to be a big white blob. you're not it's just going to be a white picture. And the reason is is because there's so much more light outside than there is inside. The the reason why it doesn't seem that way to us is because when we go outside, our pupils because of our iris get so much smaller and they let in so much less light so we can adjust to it. You got you know this, right? When you go when you're outside for a while and you come inside, everything looks dark and you have to let your eyes kind of open up and allow that light to come in. There's a huge difference between the light inside and outside that if you want to get the benefits of all of your systems coming on online. Okay? Again, think about it like you're you're flying and you have a

38:31 connecting flight. If those time schedules are all off, you're going to miss your flight and you're not going to get the appropriate thing done. It's the same thing in your in your body. All of these systems need to be come on. They need to be regulated. Your clock needs to be synchronized. And the thing that synchronizes your clock is bright light in the morning before 9:00. I would say 10 to 15 minutes is probably enough. It's probably more than enough. Here's the problem. This time of year in Ontario, you are getting up before the sun is getting up. Yeah. I mean, the sun may not even get up till I don't know what is it, 8. What is it over there? >> I would say yeah, around 8:00. >> Yeah. That's really hard to do, especially in the winter time. I mean this is the reason why people this the re this is part of the reason why people

39:16 in the winter time are more susceptible to diseases. It's the reason why we see the highest levels of mortality across the board. Um it's also because of the lack of sunlight. So what we found and it's the main reason the point being here it's the main reason why we see people with seasonal affective disorder. So this is the other pathway not not just it projecting to the super chaismatic nucleus which is the time clock of the brain but it's also projecting to the perihabenular nucleus which regulates mood and and typically it's women but also men in the winter time you know January February this is where they're depressed they're not getting enough light and and here's the typical thing that happens and I know this is in Toronto I know this because I grew up in Toronto and I've visited several times you can literally literally in the wintertime, you know

40:03 this better than I do, but for those that are listening, you can literally go in your apartment in in in North York, you can go down to the to the basement level of your apartment. You can get a path that leads directly without even going outside to the train uh to the subway station. Take the subway station down to the closest terminal down downtown. Get on the path and walk through basically, you know, miles and miles of of mallike uh underground, come to where your uh high-rise office is, and then take an elevator up and stay in your office. you lit and you can literally do this every single day and never go outside. Um it's it's an amazing infrastructure that you guys have in Toronto. I I don't know of many

40:48 other cities that have that. Uh it's quite a testament to the engineering that you've got there and the fact that you don't have earthquakes which is really uh well you just had an earthquake which is about a four but that's another topic. Here's the point is that you're not getting exposed to light at all. If you know for those of us in California it's not much different. We don't have that that underground infrastructure. But it's not a dissimilar story. You get up in the morning, you got to get in for a 7:00 shift. You go to your garage where your car is parked. You drive in the dark to your underground parking structure and you go into your building and then the sun comes up. And then you're working there till 5:00. The sun's already down and you're driving home again. No benefit of seeing any kind of light. So that type of day in day out for weeks in the in the winter time is going to wreak havoc on your circadian rhythm. Not even

41:33 to mention the fact that you're going home and as late at night, it's dark. It's supposed to be dark, but you're watching screens, you have the TV on, you're socializing, it's it's just a disaster. So, here's what we know works for that type of thing. Okay, we know this works. Buying what they call an SAD light or a sad light. It's about 10,000 lux. You turn it on and you sit in front of it for about 20 minutes because what you really need is about 3,000 lux hours. So think about that. 10,000 lux for 20 minutes, which is a third of an hour, right? So 10,000 * a 3r is about 3,00 you know 3,333 lux hours. Okay, remember that number.

42:19 This is about 11 to 16 inches in front of your face. When people do that, they are simulating the visible portion of the sunlight and they're getting the benefits as if they were looking at the sun when the sun is not up. So, it helps with circadian rhythm. It helps with mood. We we have studies on that. You can go to Amazon and buy these sad lamps, 10,000 lux. Sit in front of it for 20 minutes. Now, imagine imagine uh Jesse, if you go outside and you're going out into the sunlight and it's a 100,000 lux. If you just need 3,000 lux hours and this thing is 100,000 lux, you need a 30th of an hour. What's a 30th of

43:04 an hour? It's literally 2 minutes. 2 minutes outside in in the bright sunlight, not looking at the sun, looking directly below it or somewhere on the horizon below. Because remember your intrinsically photosensitive retinal ganglen cells are in the lower portion of the retina. So you want this light to be up in the superior visual fields that comes in. You literally only need to be outside in bright sun for 2 minutes to get the same benefit that you sitting in front of a 10,000 lux lamp. You need to be there for 20 minutes. Does that make sense? >> It does. Yeah. So it sounds like in my position the only thing in the winter to do is get one of these lamps. >> Yeah. I think it would have helped tremendously. Not only do we see that it reduces uh the depression, but there's

43:50 also some some evidence actually some evidence uh that if you were to put something called a Dawn simulation lamp. Have you heard of a Dawn simulation lamp? >> No. >> Okay. So, these are lamps that you can buy. You put them in your room and you set them to come on at a certain time of day and uh in the morning. So like 5 6:00 as if it's simulating the sunrise. And what it does is it grow it glows brighter and brighter and brighter as you're asleep as your eyes are closed. This light will then simulate you as if you were sleeping outside. And it's been actually shown to improve cognition to improve uh the quality of sleep and a whole bunch of other endpoints in terms

44:35 of health that uh that this is actually what I I have in our in our bedroom. I have actually heard. Now that you explain, >> yeah, >> if you're doing that, just to be clear, I assume you'd still want to use the SADLite afterwards. >> I would definitely recommend the SADLite if you have if you feel like you have or you've been diagnosed with seasonal affective disorder. Absolutely. I believe that it probably has other health benefits. And and here's the other health benefits. Um, we talked about the clock. So, I want to talk about cortisol a little bit, and I want to make sure that I explain this well. Prior to you getting up and getting outside and doing stuff, your body needs a chemical uh called cortisol. Cortisol

45:23 is also a steroid hormone. It would actually look very similar to vitamin D, okay? Because it actually uh has very similar effects on transcription in the nucleus. And then there's another hormone at the end of the day which we're familiar with called melatonin. Okay, melatonin is a hormone that is also secreted from the pineal gland of the brain and it comes on right before sleep. So here's this dichotomy that I want you to be very very cognizant of. Cortisol needs to spike before you get up and go and and basically as you're getting up in the morning and you're ready to do work, okay? It's getting the body ready to do work. And melatonin is the is the spike that happens right before you go in for bed. And and what you really want to have is high amplitudes of a spike. So here's the

46:09 here's the thing that we notice that happens at the beginning of the day with cortisol. When you get up, if you stay in a very dark environment and don't get outside, you will have a slight increase in cortisol. But because cortis the amount of cortisol is is tightly regulated, you still need to have the same amount of cortisol, it's just going to happen over a much longer period of time. So instead of a instead of a very sharp peak that goes up very high, sharply comes back down and you get all of your required amount of cortisol at one time and then it stays low for the rest of the day, which is the ideal. What happens is you get this

46:54 slow, you know, lethargic anemic uh growth in cortisol, but it has to stay high because it needs to give you the dose that you need for that day. And so it continues on and actually may even interfere with melatonin production later on that night when you're trying to go to bed. So here's the issue that many people have, Jesse. They say, "I can't sleep. I can't fall asleep." And by the way, this this long lethargic rise, lipidic rise of cortisol that occurs gives you the right dose, but it it's this chronic elevation of cortisol that can lead to so many metabolic problems. What you want to have, what everybody should have if they

47:41 want to have good sleep at night is a very high peaking cortisol where all of the cortisol that you need for the day is given right at the beginning. it comes down and it stays quiet for the rest of the day. That is the optimal amount of cortisol that you should get. There is one thing that will do that better than anything else, Jesse, and that is exposure to bright light in the morning. >> And to round that out, we're going to get to darkness and making sure we have that covered as well. >> Yes. >> But at night, we want to make sure we're in pitch dark. >> Yep. to help with the melatonin on the other end of what you just talked about. >> Absolutely. Yeah. So, you'll notice that the keys to good health is doing the

48:26 right thing at the right time. You know, we we have very good evidence that exercise is good for you. But we also have very good evidence that rest is good for you, right? So, how could that be that these two opposites are both good for us? How is it possible that that eating food is good for us? But at the same time, fasting is also good for us. Right? Again, these two things that are completely the opposite of each other, yet they're both good for us. And and I think the key here is is understanding that there is a time for things, and there's a time not to do things. And what we're trying to say here with light is there's a time to go out and get as much light as possible into your eyes, and that's in the morning time before 9:00. And then there's a time that you want to make

49:13 sure that you're not exposed to bright light at all and that is at night as you've just mentioned. So there's a time for light, there's a time for darkness, there's a time for eating, there's a time for fasting, uh, etc. So far when we talked about UV, we were focused on light on the skin. Now with visible, we're focused on light in the eyes. >> Yes. >> Let's expand out and talk about visible light on the skin. And I want to take our time here and get into the benefits of light on the skin if there are any. And then if there's any detriment at night if we're say wearing those blue light blocking glasses protecting the eyes but still getting dirty light we'll call it on the skin. Yeah. So this is

49:58 not a a black and white issue. Uh this there's not a a heavy demarcation here. And I'll say that when we look at visible light on the skin, which is what you brought up, this this benefit of infrared light, which we haven't gotten to yet, does bleed a little bit into the visible spectrum because there's a number of studies that show that red light um itself, which is of course visible, um can actually have a benefit. But the benefits are probably tied in with a lot of what we're about to say and when we get to infrared light, which is a topic that I just love to talk about. Um so in terms of in terms of visible light on the skin you know there is there are some studies most of them are in the red light um when we talk

50:45 about blue blocking glasses again the reason why we even talk about blue blocking glasses is because the blue blockers are obviously blocking blue light and it's those intrinsically sensitive photosensitive retinal ganglen cells that are exquisitly sensitive to that blue light. But let's face it, Jesse, they they are they're sensitive to just about any type of light. And so really, the the best thing at night is to have no light. The second best thing is to have no blue light. And the worst thing is to have all types of light. So blue blockers have their role. I would say, you know, just go for the gusto and eliminate all the light altogether. >> Okay. Do we know a lot about the sensors, if there are even sensors in

51:31 the skin when it comes to activating in a good way, and then protecting those at night so we don't get light on the skin? If that's going to affect melatonin, here's the problem that um it would have to be very uh it would have to be very close to the surface and that's because of this thing that we talk about which is the depth of penetration. So if you look at the simple physics of light, shorter wavelengths like ultraviolet light cannot penetrate very easily at all. This is the reason why it has a hard time getting through clothes. This is a this is the reason why when it hits your skin, it can get down maybe into the dermis at most. And that's really where these cholesterol derivatives are turned into uh vitamin D. But beyond

52:17 that, uh, as we start to get into the visible spectrum, yes, it can penetrate a little bit deeper, but not much deeper. Once you start getting down into muscle and into bone and the internal organs, the only type of light that's going to get down that far in the body is well into the infrared spectrum. Okay. The reason I bring this up, I believe there's one study, it may be really old, where they shone light on the back of the knee, I believe, and how that affected either melatonin or sleep. I'm getting out of my wheelhouse here, but basically, I've also heard people talk about blue blockers not being enough at night, and we need to be covering up our skin as well to block the bad light. That's very possible. Uh, that's an area that I think um may need

53:05 more research. I certainly need to look into that more. Uh I do believe that we really need to be in a very dark environment when we're sleeping and this can be a problem for people who are sleep shift workers or night shift workers I should say. Um because the rooms really need to be blacked out and it may not be enough just to have eye patches that you wear at night. Let's stick with the night shift workers. talk about what happens to their physiology even if they are doing what you just said and making sure they're conscious of blocking the bad light when they're sleeping. >> Yeah. >> Is there any hope for them? If someone is dedicated to that night shift, the best thing that they can do is to really just make the flip and and and be a

53:51 nocturnal creature every day of the week. Most most people who are night shift workers who do 12 on 12 on 12 off are only really required to work about 3 days a week, 3 to 4 days a week tops. And uh the question really becomes what do they do on the other days of the week that they're not working? Are they are they dal creatures that get up and and are awake during the day? If that's the case, then they're they're working at night when their circadian rhythm believes that they should be asleep. Okay? And that's really where the harms come in with night shift workers. Most people in my experience are those type of people. They are day people but 3 days a week they work at night. Okay. Now that's as opposed to people who are true night shift people. Uh what I say

54:40 when I say that that means that even on the days that they are not working they still get up at night and they still sleep during the day. If those people probably, if they do that correctly, and when I say correctly, I mean they're eating during the night time, they're treating their night as day and their day as night every single day of the week. They probably don't experience the same metabolic issues that we know occur in in most night shift workers, which is increased diabetes, increased cancer risk, all of these things, obesity, etc. The reason why I believe that happens is because their circadian rhythm is still firmly anchored uh as a dayshift worker and they're just working these late nights. So uh there's a recent study I

55:25 will add though there was a recent study that was done where they took people who were working dayshift they converted them into night shift workers and then they did a randomized control trial which was very interesting. What they found was in this very short-term trial, they were able to find markers metabolically that were surrogates for endstage diseases like diabetes, hypertension, obesity, etc. And I I don't recall what the names of those biomarkers are, but you could look it up if you get the study. What they did in the study was something very interesting. They simply randomized the these groups of people to either eating at night or whenever they wanted to. And those people that were

56:12 only allowed to eat during the day when they were sleeping. So how did they eat? They would they would eat and then sleep for about 3 or 4 hours and then eat and then sleep for about 3 or 4 hours and then eat etc. In other words, the key was is that when they went into work at night, they did not consume any calories. Okay. What they found in that study very interestingly is that that intervention group that did not eat any food while they were working at night, they were able to reduce these surrogate markers of these bad diseases by about 80 to 90%. Fascinating. I look I'm a night shift worker. I occasionally have to do night shifts in the intensive care unit. Uh I am certainly not a uh a creature whose

56:59 circadian rhythm is at night. I am firmly in the day. So when I do these things, I have to be so as a result of that I have adopted this practice even though we need to do more studies on this of not eating anything while I do that night shift work and only eating during the day uh to try to mitigate some of these factors that are involved with night shift work. We talked about blue light blockers. I want to make sure we cover sunglasses because we've talked about different benefits in the morning specifically getting visible light in the eyes. Just like we talked about sunblock before, we could think of glasses as a sunblock for the eyes. >> Yeah. >> Obviously something we want to be aware

57:44 of if we're trying to get this light in our eyes in the morning. >> Yeah. So, it's a little tricky. If you've got reading glasses, no problem. the the benefits of oh I'm sorry not reading glasses just regular glasses to be able to see uh yeah I would not recommend taking those off if you're walking around outside we want people to be able to see so uh contacts I would also put into that category however if you're putting on sunglasses for that purpose realize that you're diminishing the very reason why I was recommending that you go outside in the first place and that's because the amount of light outside is so much brighter. Why would you want to diminish that with a tinted glass that's going to diminish that or or change the spectrum that I

58:31 believe was perfectly designed for the effects that it gets when you go outside? So, I I would not recommend sunglasses. Now, I I say that with the Proviso that there are many people that have eye problems, have retina problems. they're being followed by retina specialists or opthalmologists and uh if they've got a recommendation because they have a particular medical problem to wear those glasses then I certainly don't want to interfere with that uh recommendation from their specialist. But in people who don't have issues with their eyes, if you want to get the benefit of circadian rhythm, the benefit of mood, you really want to go outside and not really have anything in in in between the sun and your eyes. Again, not recommending that you look directly at the sun. I think that's something

59:18 that we can all agree that we shouldn't do. In fact, if anything, you want to look well below the sun to allow that light to get into the uh inferior uh retina at the back of your eye. So, definitely recommend that. >> What do you think about these more mild blue light blockers? They're yellow or a slight tint. People are wearing them when they're on their computers during the day. Any value there? >> I haven't seen data. Uh I I know that there's been some data looking at night shift. They call the night shift where they where they switch the hue of the screen and uh from my understanding and the data that I've seen on that and correct me if I if there's a new study. It really didn't have the effect that they were looking for. >> How do you feel about red light panels? You brought up red light before

1:00:04 and we can also expand out to lasers using >> Yeah. >> light as a therapeutic tool. That's a discussion I think that's going to be better had once we talk about uh infrared light and um there's some exciting work that is now going into exactly how does infrared and red which are both long wavelength energies how are they actually affecting the mitochondria and what what is actually going on there's there's new data coming out and actually I've I've uh collaborated ated with um Glenn Jeffrey, Bob Fosbury and Scott Zimmerman who have published on this before and we should have a paper coming out uh very shortly. But the short answer to your

1:00:49 question is is I think the data is showing that mono chromatic light, what do I mean by monochromatic light, I'm talking about lasers, I'm talking about LED lights, are not as effective at doing the job that we want them to do as is diverse multi-wavelength type of light that we would see either from an incandescent bulb or from the sun itself. Okay, we'll come back to that in a little bit then. I want to stick where we're at for now. People that are indoors trying to get good light, whether it be on the skin or into the eyes, but they're doing it through windows.

1:01:35 Is there any benefit there? It depends on the window. So, there's always going to be some degrading of the wavelength. Again, we already talked about ultraviolet light really cannot penetrate through any kind of window very well. It's going to be eliminated because I mean there are certain there are certain materials we actually talked to someone who found a material that has a lot of uh transparency to ultraviolet light cuz they're interested in in getting that benefit. But for the most part, the commercial types of window materials that we have in homes tends to block uh ultraviolet light. Now, variably it can block infrared light and we'll talk about the benefits of that, but uh you really want to get outside and not behind a glass. You quickly touched on incandescent light. Let's

1:02:22 talk about lighting throughout a home. Given where modern technology is, the LED lights are being pushed upon us. What do you do for yourself? >> I think the addition of of an incandescent bulb in a room full of LEDs is actually beneficial. We actually have some data on that. Glenn Jeffrey just published a paper uh in nature scientific reports showing that uh visual discrimination of color which was an endpoint of mitochondrial function in the retina was improved over 20%. With the simple addition of a 60W incandescent light bulb in an LED environment. Uh I think that's a tremendous and by the way that's one of the reasons why that data is one of the

1:03:07 reasons why I believe that incandescent bulbs are better than just narrow band LED uh red light or infrared light therapy because Glenn Jeffrey repeated

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