Photobiology, Sunlight, Firelight, Incandescent Bulbs vs. LEDs, Mitochondria, Melatonin, Sunscreen & the Optics of the Body | Scott Zimmerman | #146

About the guest: Scott Zimmerman is an optical engineer and photobiology expert

Episode summary: Nick and Scott talk about: how light interacts with the body and affects our cells; melatonin as an antioxidant;  how red & near-infrared light affect mitochondria; sunlight, fire light, and artificial light; incandescent light bulbs vs. LEDs; negative health effects of artificial light; sunscreen & makeup; red & near-infrared light therapy; the optical properties of the human body; and more.*This content is never meant to serve as medical advice.

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* Episode transcript below.

Full AI-generated transcript below. Beware of typos & mistranslations!

Scott Zimmerman 5:08

about your background, I looked a little bit but I didn't guess, get a follow up date on.

Nick Jikomes 5:14

Yeah. Um, so my background is in research science. So I did a PhD in neuroscience. And I was a researcher for a number of years, and then moved into the technology sector in the cannabis industry, actually. And I worked in that for a number of years. And now I pretty much just do this and some consulting advisory work on the side. But I've been, you know, I've been interested in learning more about the effects of light. Beyond the obvious, obviously, we have a visual system that allows us to see things that's actually partly what I did my PhD research, and we all know about UV light, and it's mutagenic effects. And, you know, that's the reason why we we are so often wearing sunscreen, but it's only been fairly recently for me that I've come to learn more and appreciate that, you know, the other wavelengths of light are also having really interesting physiological effects. And you seem to be a good person to talk to you about that.

Scott Zimmerman 6:13

Well, you know, it's, I think it's an amazing field, to be quite honest, it hasn't really been tapped into very well. I mean, there's been a lot of work done on photobiomodulation, and red light therapies and things of that nature, that got some of that kind of mixed reviews from the medical community, and all that. But I, what I was amazed is that there really wasn't, I'm an optics guy, you know, so I was just amazed that there was so little known about the differences and the similarities there are, you know, in the body and how it functions optically, especially in the near infrared, because you have such, you have to move from a two dimensional to more of a three dimensional way of looking at it, because there's so much penetration and propagation that occurs at some wavelengths. And I think, have you seen Bob Fosse Berry's pictures in the near infrared of the hand and think, no, no,

Nick Jikomes 7:07

I don't think so.

Scott Zimmerman 7:09

When we get done, I'll ship it to you ship you some pictures. But what you start to find out is, is that, on an optic standpoint, we're pretty infinitesimal in our infant in our maturity of our ability to even measure are to measure or to essentially, model how light propagates in the body. And unfortunately, most people go and they grab a cadaver or sheep's head, and they put a laser on the outside and they measure, put a detector on the inside and say, Oh, you only get 5% transmission? Well, that's, that's a bogus way of making the measurement, it doesn't actually work. That way, when you're dealing with scattering volumes, it's one of the hardest measurements to make and optics there is. And so what happens is, is that I like to give people kind of an analogy, you know, if you put an ice cube, a nice clear ice cube, in front of that laser, and you have a detector sitting back there, then you get almost all the light 100, almost 100% transmission less the for now losses. If you take that same size, and you make it a snowball, that's an ice cube, same size, you shine the laser and do it, the entire thing lights up, and the transmission goes down to next to nothing. Because what happens is most of the light is scattering into the volume and changing its direction and reflecting back twice knows why and all this other great stuff. So, you know, unfortunately, to try a model that is extremely complex and hard to do. And really, we lack a lot of the body is a lot farther along and you're doing optics in the body than than we are and our ability to actually model it and understanding.

Nick Jikomes 9:00

Yeah, yeah. Yeah, that makes sense, right? I mean, we've we've been interacting, as, you know, creatures walking the earth, we have a very, very long evolutionary history with the sun present as a huge environmental stimulus. And so our bodies have adapted to it and, you know, figured out so to speak, how to respond to and utilize that light in ways that are beyond our, you know, beyond our ability to model it as as you said, Yeah,

Scott Zimmerman 9:29

well, and and, unfortunately, there's been some pretty sloppy, myself included, but there's been some sloppy use of terminology. It's like if you look and people talk about daylight while they talk about daylight only in terms of our care about it in terms of usually what we can see with our eye, and yet that represents only 10% of the solar spectrum. And that was the part that was just so amazing to me is the minute I started looking at, okay, how does light propagate in the body? Do you start to see that the body is actually doing things optically to increase the ratios of Near Infrared to visible, especially in the brain, you know, if you do actually look at how that light propagates in the brain, it gets through the skin through the skull in the near infrared. And then it gets literally like guided down into the features of the brain. And it just happens that all the gray matter is out on the outside periphery. Optically, it makes total sense.

Nick Jikomes 10:30

Yeah, let's Let's back up for a second and give give people some concepts and some background here. Let's just talk about sunlight. First of all, so you just mentioned right that as many people sort of under appreciate, the visible part of the sunlight spectrum is only a fraction of what's actually coming from the sun. Can you talk a little bit about just sunlight in general? What does that full light spectrum look like? How much of it is near infrared light? What is near infrared light? And what are we if we if we go outside during the day, what are we actually being exposed to? Yeah,

Scott Zimmerman 11:04

I mean, that's a great question. You know, sunlight runs from 250 nanometers down to beyond 3000 nanometers. And of that, about 10% of it is the visible and running from 400 to 700, depending on how you want to, you know, these are kind of artificial things. So we define visible to be x and near infrared to be y. But to some extent, but what you have is, is that, like you walk outside, you're looking at a blue sky, and everybody says blue, bad, blue, bad, you know, no blue is not bad. But the blue that you see in a blue sky, is actually a very broadband distribution of wavelengths that that has a gives you the impression of blue, it's a blue, cyan, all these different colors. But then if you go on out, and bear in mind that most of the problem is, is that most of the laboratories don't have the capability to measure accurate or easily the near infrared. So it's been kind of ignored. And so what he see in that blue sky is is that there's this huge tail, long tail of near infrared. That is that is built into what you see as blue. But not only that, you have to think about it from the standpoint of the for what we're doing, I really could care less what goes through the pupil, it's not what I'm looking at, I'm looking at what is the body absorbing and taking into itself. And in the near infrared, what happens is, is that when you walk outside, it's not just the Sun, sun from this light from the sun, it's the light from the Raleigh scatter, that gives you the blue haze and or the blue color of the sky. But then if you look at what happens in your surroundings, the plants and around you are strongly absorbing visible wavelengths. That's how we can tell whether or not that's a good apple or a bad apple or bad snake or good snake. So that's very important. But in the near infrared, all those plants are reflecting near infrared, so you're kind of walking around in this integrating sphere of light, that's predominantly near infrared. And, in in our work, it matters, how many square meters of skin or body are you is getting absorbing energy. And so when

Nick Jikomes 13:23

we, when we go outside in the sunlight, it's not just photons that have done a straight shot from the sun, down to earth and onto our bodies. It's also photons to get scattered in the atmosphere, and then get to us that reflect off of plants and other things and bounce back up to us. And it's this whole sort of ecosystem of light.

Scott Zimmerman 13:43

Yeah, exactly. Right. And, you know, the point is, is that, you know, those you think about from a solid, you know, solid angle, you know, three dimensionally here, you know, likes coming down from the sun, like I'm outside now I'm getting my head and my forehead and all that. But in general, it's got a fairly low solid angle that is coming into my body, but surrounding me, everything around me is reflecting that light and when coupling it in into a much larger area, large larger sort of solid, solid angle. So you're getting all this near infrared in particular, kicking even dirt has a higher reflectivity in the near infrared than it does in the visible. So So

Nick Jikomes 14:29

is it are we like hitting our body? There? It sounds like there's more near infrared light than you would expect from just considering the direct sunlight. Because Okay, I see.

Scott Zimmerman 14:42

Absolutely and what we've been trying to get people to, to understand are to look at is is that in when you're in direct sunlight, high noon, if you look at the on an optical whitespaces there's one optical say one optic wide of visible, while then there's one optical lot of near infrared, in that direct sunlight. But then the minute you start to look at how strongly the other stuff absorbs the visible, all of a sudden, once you walk under a shade tree, that ratio of near infrared, the visible in optical Watts increases to three to one, you go on, you walk down and you sit around a campfire, it's 10 to one. And then what she then went optically, what happens is, which is absolutely the most humbling and amazing thing I think, is is that the body then goes and it does certain things in very scent in our most sensitive tissues, to guarantee that that ratio is even higher, like in your eye, most of the photons that actually hit the retina, don't go through your pupil, they actually go through your skull, air and your eyelids, and in scatter into the in the near infrared, because the transmission your eyelids, people walk outside and you're in a sunny day, and you close your eyes and you look up towards the sun, you'll see this orange glow, well that is the that is the red edge, that then opens up this transmission window in the near infrared. So And what's amazing is the eye has a larger transmission window, as far as the humerus humor and all that other stuff in the near infrared than it does in the visible. Why? Well, because the near infrared is stimulating blood flow oxygenation, leading students glucose it's having these other effects. And the body has made a choice to have over a dat adaptation The millions years that it has a imaging optic, which is your through your pupil, but it has a non imaging collector, which is gathering life near infrared in particular and making sure that it goes on the retina, the retina is the most beloved or the most metabolically active tissue we have. The same thing happens with the brain. From the standpoint of the you can you can easily Yeah, have you ever, you know totally ghost story and stuff shoved a Pin Light up your nose or whatever, when you turn nice red, well, that's again, the red edge. If you go into the near infrared, literally, the light is pumped into the cerebral spinal fluid, which then is because of its it has a peak transmission in the near infrared and low scatter. So it then like guides it down into the fissures of the brain. The most amazing thing is is the one you're talking to looking at a woman who's a pregnant woman, what happens when the early part of the pregnancy is the her skin and all that it filters out the greens and the blues and the UV, but allow some level of transmission of the near infrared. As the pregnancy progresses, the skin starts to stretch, it expands the spectrum that the fetus is exposed to the amniotic fluid has a peak transmission in the near infrared as well. And so you what you start seeing is you start seeing all these different things that the body is doing to essentially increase, especially at critical times, like the theory of fetal development. The amount of Near Infrared that is being provided relative to the visible doesn't mean brute bad or anything. But

Nick Jikomes 18:17

yeah, so it sounds like, you know, obviously light is a huge stimulus for us. It historically was an even bigger stimulus when we weren't, you know, living in houses all day long. So, you know, it was such a huge stimulus, naturally, organisms are going to be evolving at adaptations that enable them to survive in the presence of that stimulus to take advantage of that stimulus to do, you know, to do things that are going to facilitate survival, what you're saying is that the infrared is such a large component that in many ways, just the biomechanical structural adaptations of the body have evolved over time to actually sort of almost magnify the effects of the near infrared.

Scott Zimmerman 18:57

Yeah, well, I mean, there's always an advantage. If you look at when I first Well, I guess I, I'm trying to make it clear is is that, you know, the body has gone to extreme lengths, to guarantee that it is the legacy increasing the ratio of Near Infrared divisible, Ban, what we're seeing from all the photobiomodulation and red light, that red light, longer wavelengths have a huge impact on a wide range of different biological functions. And you know, I been working a lot with Glenn Jeffery Elgar in England, and he's done this really great study where he took in exposed just for square, you know, a small area on a person's back to with red light and a short duration and all of a sudden and under a glucose challenge, and he was able to show that the red light causes the glucose levels to drop systemically even though he's only exposing a small patch of the of the body and it was But he's showing that it's changing biologically, the optive homoeostasis, or whatever you want to call it, the baseline against which we're operating, when we're exposed to these longer wavelengths.

Nick Jikomes 20:11

So if a small patch of skin is exposed to red light, it can affect body wide blood glucose levels. That's

Scott Zimmerman 20:20

what it appears to be going on within the thing, and you think about it, you know, Glenn makes the point, he says, you know, you can't have one part of your body doing one thing, and the other part of the body doing the other thing, it's something else entirely, and there not be a consequence. So there's this natural fact where they, you know, you start to have a hotspot someplace, while you tend to the rest of the body kicks in to kind of make everything okay, you know, and so I think that's, to me, is really fascinating that it's going on, but so

Nick Jikomes 20:51

for the people that don't know, can you just give us a basic physical definition for red and near infrared light? And then start to talk about some of the, you know, what are some of the more salient physiological effects that we know, those bands of light can cause in a human? Okay, well,

Scott Zimmerman 21:07

I mean, again, we kind of arbitrarily picked, what we define, if you look at the CIE, they go from 380 out to 850. But in reality, in our world now, you know, we're talking about 400 nanometers to about 650 nanometers is our definition of visible light when we provide it artificially. But what, to me, what defines where you should divide the two and deep red and near infrared are kind of, to me kind of lumped together is where you have that red edge, you know, where all of a sudden, we go from something that is fairly strongly absorbing to something that is allowing propagating DNA deep into the body, and that curves somewhere around the 630 650 nanometer region, and runs up to 700. But you know, that those biological, what you end up with is a series of biological windows, in the near infrared, where the light can propagate inches into the body. And then what, that's where you have to move from, as I said, you know, if you're looking at UV, most of it happens at almost all the photons are absorbed in the outer 50 microns to millimeter Max, you know, blues and sy hands. But in the near infrared, it's quite the opposite, you know, you get into the longer wavelengths. And in the within these biological windows, where the absorption is very low, and the scatter is very, is very, for what we call an isotropic. Or it's scattered, you get this effect, like I said, like the ice cube, where you're essentially distributing the, you know, if I have, you know, I cover up everything, but one little spot on my head or whatever, and I love the near infrared, it's going to propagate out into a much larger area. And you're also having this biological effect, where it's signaling to the other mitochondria that you guys need a kick, kick into gear here, because I'm getting, you know, I'm getting burned, or I'm getting, you know, so whatever. And so it to me, it's an amazingly complex arrangement. But it kind of makes sense, when you start thinking about how the body is, uh, has had to adapt to this environment. I mean, you know, it's just, it's just a huge amount of energy. I mean, people, it, if you look at it, historically, the energy from sunlight into the body has been the largest energy input to the body. Yeah, period, it's more than food, it's more than anything else, like 30 mega joules up to 30 mega joules a day. And that's a huge amount of energy. And, but if you look at that, and from the standpoint of how much of that is near infrared, it's actually can be as high as 90% of that can be near infrared, and

Nick Jikomes 24:00

other filtering. And you said, the near infrared can penetrate several inches into the body is so I mean, that makes sense when I think about it from a physics standpoint, but, you know, normally we just think of light hitting surfaces of skin and, you know, bouncing right off or not going very deep. This is it's going if it's going four inches deep, it's touching the cells of my internal organs, and that's exactly,

Scott Zimmerman 24:22

exactly. And what we're trying to show is, is that, especially with children, it's, you know, it's the penetration depth, the characteristics are the same, whether you're a child or adult or a female, whatever. But if you look at from the standpoint of smaller children, in particular, almost 100% of their cells are being are seeing some level of near infrared, it's been filtered out the blue and the green, but they're exposed to it and it's we're showing, you know, Glenn showing, and we showed what tried to show with our melatonin research and stuff is is that it's having a huge impact on their hormone levels. Well, now all of a sudden, what do we did the what do we do? We went in, we said, Okay, kids shouldn't play outside, they're gonna get skin cancer, we would sit inside Watch out on our computer all day in a building that has a near infrared blocking glass glazing, that's preventing if so I would say I keep on trying to say is that we are looking at the largest reduction in solar exposure in human history. Nobody notices it, per se. But that's what's actually happened. And it's in because, you know, people don't see near infrared. So how do they know it's not there? You know, but to and, again, if you look at from the physiological effects we know of, we know that it affects glucose levels, we know that it impacts hypertension, we know that it impacts anxiety, and a number of neurological things. We know that it impacts how hormones what hormone generations and hormone ratios. And my big concern is, is that what we've created with our artificial environment, is we are like under constant stimulation to generate cortisol. And

Nick Jikomes 26:14

what why is that does it have to do with the the more blue light and the lower ratio of infrared to visible light?

Scott Zimmerman 26:23

Well, what it has to do with it that we're constantly, cortisol is important. Don't get me wrong, I'm not saying it's not important. But it's a it's a fight or flight response. It's pretty it's designed to actually protect us. So when you get so all of a sudden, a bunch of bright light into your face, your cortisol levels go up, you go eat a bunch of stuff, your cortisol levels go up, you get you do, you know, any any activity, exercise activity, or cortisol. But in nature, when we're in nature, there is a complimentary effect associated with you know, we got nine orders of magnitude of from direct sunlight all the way down to moonlight. And so that kind of control system can only be done using ratios of opposing things. So cortisol is opposed by melatonin. What we showed in our biology paper was is that, hey, during exercise or doing anything or going outside, all of a sudden the cortisol levels go up. Doesn't matter what time of day it is, you know, this is totally independent of circadian. The time it goes up, but so does melatonin. You know, how is the mouse? Where's melatonin being created at 9am? At levels or three or four times what it is at nighttime? Well, it's because the all these are cells are literally generating melatonin. And this is the debate that's been going on for 40 years about or what's what's all this melatonin come from? Well, I think we've shown that it's from, you know, when you start doing exercise, your muscle cells generate reactive oxygen species. And in response, it starts generating tons of melatonin, because it's an amazing antioxidant.

Nick Jikomes 28:01

I see. Yeah, I knew that I knew that melatonin was anti a strong antioxidant. But what I didn't know until recently, and what I think most people don't appreciate is when we think about melatonin, we usually think about melatonin that gets produced when light levels go down. It's called the hormone of darkness. And we think about it coming from the brain from the pineal gland and entering into circulation and being important for setting and coordinating the circadian rhythm of the body that that dictates our sleep wake cycles and other things. But what you're saying is melatonin doesn't just come from the pineal gland. It's not just for the circadian biology, it's it's actually produced in sounds like all cells are most cells,

Scott Zimmerman 28:43

all cells because I mean, you think about it, what the the experiment was really quite simple. They took a number of people, they put them on treadmills, and our stair steppers. And they monitored their melatonin levels at 9am in the morning, and they did the exercise before hours, you know, is a pretty strenuous exercise. What you saw was you saw within 10 minutes the melatonin level in the blood went up to 200 pico grams per milliliter, that's two or three times what it normally would be at at night. When it's supposed to be doing what it's doing. And I'm not district I'm not discrediting or arguing with circadian at all. It's it's a process, but the brain in order for the brain to function at 80% It was Jay it's got to generate a ton of reactive oxygen species. The most the most potent antioxidant we have is melatonin because it's a it cascades down all its metabolites are also antioxidants. So you get this cascading effect. So the brain the body, and only in its infinite wisdom, made a pineal gland generates melatonin during periods of low cellular activity when it There isn't much being generated by the other cells. And when the brain actually needs some kind of help. And like I say, I mean, it's it's more than just an accident that melatonin was selected for the pineal gland. But now what we're showing is, is that if you do in the only way you can really measure circadian melatonin is you put somebody out on a bed, make them quiet in the dark. And then you can start seeing these circadian effects. The minute you turn on a light or shake them or make them go do a little bit of exercise, all bets are off, those hormone levels are moving rapidly. And so what was just absolutely fascinating was that this in particular, Theron's work showed that melatonin, you know, ramped up within 1020 minutes to very high levels and then plateaued during the exercise. And then once you quit the exercise, they went back down. So you have a great dose response, you know, argument going on, where's

Nick Jikomes 31:02

being synthesized? Where's it coming from within cells?

Scott Zimmerman 31:07

May the highest level in the mitochondria itself, there appears? That's that's the argument.

Nick Jikomes 31:13

I see. Okay, so it hasn't been shown directly. But I guess the argument would be the mitochondria, you know, these are the, the organelles within our cells that produce ATP, the energy currency that we use to power our cells. This is the site of oxidative phosphorylation and the whole chain of events that that makes the energy of the cell, that process is naturally pretty intensive. And so it produces a lot of reactive reactive oxygen species. So I guess you would expect the mitochondria to also be equipped with antioxidant capabilities to to handle

Scott Zimmerman 31:45

that. And that was what was kind of cool about this recent paper by Jeffrey, he is that what he did, is he took a red light expose the area. And not only did he measure that way, it was a glucose challenge test. And what he showed is, is that the people that didn't have the red light, you know, had x level and the people that did have the red light or 27%, level lower. But what was even more important was that he measured the co2 levels. So the co2 levels then went up when you got the red light exposure, which is a clear indication that the mitochondria is essentially kicking into high gear. And so because of the way, you know, to generate the ATP and all that other stuff. So I mean, I think that there's some fairly direct evidence that it is the mitochondria itself. But again, this has been a debate that Russ Reed Ritter has been fighting for 40 years. And, you know, but I do believe that the data from the exercise and from the zoo's work on exercise and being outdoors, make it pretty clear that literally all cells are capable of generating, but mitochondria are made melatonin, and, and a variety of other things. So yeah,

Nick Jikomes 33:02

I mean, when I think about it, in evolutionary terms, so so for those listening, you know, recall that mitochondria are organelles of our cells, they produce ATP, the energy that our cells use, they actually evolved from cyanobacteria. So they they are, they used to be bacteria effectively, and cyanobacteria are well known for their light sensitive light sensing and light responding capabilities. Chloroplasts in plants are basically the analog of mitochondria for us. And that's, that's the organelle in plants that is actually photosynthetic. They also came from cyanobacteria. Obviously, they're sensing light. So it makes sense that mitochondria would have these light sensing capabilities based on where they came from. What do we know there about like, the different wavelengths that they sense? Is it just near infrared? Is it other wavelengths? Like, what are the light sensing capabilities of the mitochondria?

Scott Zimmerman 33:51

Well, I mean, if you look at Peter lights work up in Alberta and Canada, he was actually did some really good work where he did some single cell patch studies where he actually measured the wall potential on say, individual cells exposed to different wavelengths. And what you find is, is that in within the cell, especially the fat cells, there is actually a higher level of melanopsin in the, in those cells than there is in the retina, you know, so you can probably think he evolutionarily, there was a point where we didn't have eyes, but the skin was photosensitive, and then the eyes came into the whole picture. And, and some of that, you know, some of that melanopsin went into the eye for other reasons for the circadian characteristics. But then if you look at it from the standpoint of the effect on of longer wavelengths, you have to take into account that, you know, I don't have to do much I don't have to generate much melatonin, if I am stimulating all the mitochondria, because you're talking about trillions and trillions of cells. have mitochondria that could be over, it'd be stimulated or by the longer wavelengths, because it's penetrating so deep in the mind, I would tell everybody to go look at Bob Fosse Barry's pictures of the hand, but you'll literally see is that the entire hand glows at 850 nanometers. And then you can kind of see the blood vessels. And what it was really showing is, it's a cute optical collector system. In that, you know, what happens is the light is propagated, Bob calls it scattering as weakly scattering matrix with weak absorbers. So what happens is the once a light enters the hand, you know, it starts to bounce around, and eventually gets to the point that it you know, the, that it finds a weak absorber to be absorbed. Yeah, there's a picture of it right there.

Nick Jikomes 35:53

Oh, wow. Yeah. So so for those just listening, yeah, we're looking at this picture with describe what we're looking at Scott?

Scott Zimmerman 35:59

Well, this is 850 nanometer, Bob, Fosbury, he's done a number of these, he tell everybody go look at his Flickr page. He's amazing guy. Anyway, he's got 859 nanometer of LED emitter, he's got a camera that's sensitive to 850 nanometers. And, you know, you see how the light this is like, he's got his hand over essentially a point source. But then what happens is, is that it goes into as I said, like this cube of snow, snow, and it just bounces around, you know, anybody who's built a Snow, Snow igloo or snow fort, and during a sunny day, can you get the impression of how light scatters and is distributed, by by these, this though, and the whole key is, is that in the near infrared, the absorption coefficients are dropping down so low. And the scatter is all these mostly forward that did let you kind of fill the volume. And so now you get the impression that in the near infrared, the body is designed to guarantee the high level of, of number of the cells are being exposed in the near infrared, like I'm sitting out here right now. And I have a T shirt, I have a shirt on I pants shorts, and, Paul, that it doesn't really matter in the near infrared, as Bob also shows, you know, you can have multiple layers of clothing on and the near infrared actually penetrates through that clothing. So, you know, unfortunately, what's happened in our environment today is is that blue is bad? Well, I believe blue is bad, because we took the near infrared away, I see it's about the ratios. Here's the ratios, because as I said, any control system has to have a positive and negative feedback component to maintain, you know, equal or stay, you know, to that steady state. And what we did is we lopped off huge portions of the solar spectrum. And now you've got the stimulation going on for cortisol, you know, you, you're, in

Nick Jikomes 38:03

some sense, some sense of the light bulbs in many people's homes, we think of it as blue light, but in some sense, it might be better to think of it as the lack of other wavelengths of light. Exactly.

Scott Zimmerman 38:13

That's a great way to put it. And yeah, it's hard because you know, something you can't see, he's not important to you, you know, compared to the other. And, and what I find fascinating is we developed some light sources to try and mimic add the near infrared back in. And it's children and women in particular that respond to it. Number one, women have much higher color sensitivity than men do. They can tell 15 Shades of Blue, and we see too, and so never argue with your significant other. That kind of situation, because the reality is, she has an advantage over you. Now we have an advantage over noticing that there's movement in the brush. But but you know, and that's what I've been trying to. We've been focused on here lately. I did a podcast with Sarah pew, on women. And women have entirely different responses to sunlight that men do. And it's a

Nick Jikomes 39:14

it's an awesome example. What are some examples of that? Well,

Scott Zimmerman 39:18

number one, well, part of it is is that? Well, number one is that women have thinner skin, literally thinner skin, they have less collagen, so more of the light penetrates deeper into their body. They tend to be it we have very little if any understanding of its effects on female hormones. But we were trying it it's kind of I was talking to Sarah and she said, Scott, did you know that all the majority of the rats that are used for testing drugs are all male? I said no. I But it turns out that that's the case. So there's this general lack of understanding, you know, I'd say there's actually, you know, needs to be some key research done in that area. To understand what affected the differences, all I can tell you is is that

Nick Jikomes 40:19

was because the light penetrates to such a different extent, it

Scott Zimmerman 40:23

different extent. And then there's new indications, some papers that are coming out showing that female Marik Andreea may be less of that they may have less mitochondria, but that mitochondria tends to be more efficient at generating ATP. So, I mean, you know, I guess I'm just trying to make the point that and then we did, I think, to our knowledge, we're about the only people that have actually measured much in the black community. And what you find is, is that someone with high melanin content needs three to four times even six times the amount of near infrared, to generate the same level of stimulation that a person who has very low melanin content is. And so and again, that's another amazing thing where we're so most of the optical models are based on the assumptions of particular layers, with an absorption coefficient and scattering coefficient and things of that nature. Yet, what the body does is it takes melanin and puts it in a little granule, like a speck of pepper. And what that does is that optically changes how much so more near infrared actually goes through that situation than if I uniformly distributed the melanin through that layer. So there's all these little tricks the body is doing to optimize the amount of Near Infrared that is getting into the cells underneath, we and we,

Nick Jikomes 41:47

when we wear sunscreen, does it block all wavelengths, including near infrared.

Scott Zimmerman 41:54

Now, one of the art paper, what we do is we do optical models, and try and understand where the photons are going in the body. And then I, early on, I was lucky enough to see work by Zastrow, where he did a cat did a measurement, he was in the cosmetic industry. And what he did is he started, he measured the amount of free radical generation as a function of wavelength throughout the visible and into a little bit into the near infrared. And what you find is, is that some modern sunscreen is mainly targeting UVA, UVB and UVC. And then there's a cut off. But what he showed was that the, if you take skin, and you measure the free radicals, in exposure to the UV portion, you get x, if you actually then take the same piece of similar sin and you measure from blocking the UV, but putting in the visible, you get x again, there's equal amounts of free radicals being generated in the visible. So what ends up happening when you do sunscreen, nobody is going to buy sunscreen that makes them look like blackface just not going to happen. So what happens is, is that they cut off in the UVA and, and make it so that you don't see the effect. But literally, by doing that, the UV portion is what actually gives you sunburn. And tells you hey dummy, it's time to get in out of the sun. Well, now you block that you can stay outside longer, but it increases your exposure to the visible portion.

Nick Jikomes 43:34

And that is also generating oxidative stress,

Scott Zimmerman 43:38

oxidative stress and

Nick Jikomes 43:42

so is what is what you're saying that most sunscreens actually make it easier for people to expose themselves to more oxidative stress because they can stay out in the sun longer.

Scott Zimmerman 43:52

Yes, and what's the what appears to be the case if you look at optically and we wrote this show this art paper is that optically, most the higher percentage of the blues and violets and cyan lines are localized in the basal layer, which may explain why men in particular have are some people have higher levels of basal cell carcinoma. And because that's the cells that are actually getting extra pumping by this using sunscreens. So there was a company down in Australia that tried to introduce some level of blockage or absorption and can't give you a brown hazed Hill type thing. But to really do it right I mean, a person with high melanin content is basically immune from melanoma and those type of things. Person with white skin is very susceptible to it. But it's also showing that is putting some sunscreen and my biggest problem Is that we again, because we're not willing to understand the differences, as well as how we're similar, you know, you put generically, almost all makeup now has SPF in it? Well, someone with a woman with very dark skin had does actually struggling to generate enough UV D, our vitamin D and other hormones, including estradiol, because the basic components are actually generated in the outer 50 microns of the skin. So you you're sitting there, and you're saying to yourself, you know, we're actually making it worse for all these different groups, because we don't want to admit that there's a difference. And it said, it's unfortunate, I think,

Nick Jikomes 45:41

yes, I mean, depending on your skin color in your background, depending on if you're male or female, you're going to have different light needs, basically. Yeah, but we're giving everyone the same application of things like sunscreens, or women's makeup, and it is differentially negatively impacting different types of people with different types of skin.

Scott Zimmerman 46:02

Yeah, and I'm not trying to advocate you don't put sunscreen on if that's what you want to do. But understand that you're only solving half the problem, you need to wear a hat, you need to go out and, you know, get a certain amount. And like now, I mean, he's getting later in the day here, where

Nick Jikomes 46:19

he called, Are you calling in from

Scott Zimmerman 46:20

New Jersey?

Nick Jikomes 46:22

And so Okay, so what's the time of day right now? And like, how much is what do you for yourself, consider an appropriate amount of sun getting out into the sunlight? without sunscreen,

Scott Zimmerman 46:34

I would go, what I would suggest is, number one, the best thing is go play under the snow, go do your stuff under the shade of a tree, if that's not available, then have a hat on and then be I would go from, you know, early morning to about 10 or something, and then kind of go into the shade like we are you would think of you know, you you think an animal doesn't sit out and then the middle of a sudden the desert? Goes find the day tree. Yeah. Which I mean, some of this is just common sense.

Nick Jikomes 47:05

Right? Which I mean, but if you think about it, like modern culture, a lot of people like right, they're specifically going out at the beach in the middle of the day indirect sunlight, with no shade on purpose, and not going out in the early morning. And in your sunset. Yeah,

Scott Zimmerman 47:19

and and, you know, some of that, I mean, most of us go 5061 65. So yeah, I haven't gotten any melanoma yet. And I've been grew up in Kansas, putting up hay, and you know, we didn't have sunscreen back then. And all this kind of stuff. So, you know, a little bit of common sense comes into play on this whole thing, in my opinion, you know, you don't, you don't want to overdo it, and you start to get a little bit red go in. But that was the really kind of, I tried to publish the paper on it, and it got shut down. Because it basically said, you know, that it's maybe not the best idea to put sunscreen, and in all these different people. And, in particular, if you're only going to block the UV portion, you know, you literally, it's very hard with some of these SPS that look transparent, to generate a you know, even get a sunburn. You know, that's one of the one of their functions. Yeah, I'm not arguing about that. But, you know, the body was divined to essentially tell you, you need to get in and out of the sun. And the sunburn is part of that parcel of that, that learning process, I guess I'd say it's one year growing up.

Nick Jikomes 48:37

Would you say that, like, you know, argue, could you make the argument that the optimal way to regulate your exposure to the sunlight would be to regulate your own behavior in response to how your skin's responding in the absence of sunscreen such that you're getting sunlight, but avoiding sunburn?

Scott Zimmerman 48:53

Yeah. Yes. I mean, I think that that, you know, people are always looking for a pill, or something that lets them do something they know, they shouldn't do. And, you know, that's kind of what do I think any of us would be honest, you know, other than people that really want to get there golden Dan, you know, the bottom line is most of us know, I really shouldn't just be standing out here without some level of protection. And it doesn't take much I mean, and like I say, if you look at melanin is absorption optical absorption characteristics, strongly absorbed in the UV, and then it drops like a rock down to 700 800 nanometers, and it has almost no absorption. And in fact, if I try and mimic melanin, using charcoal particles or whatever, you what you'll find is is that in for a broadband absorber, it literally is this long tail versus melanin, which is a spike up in the UV and drops down like a rock in the near infrared, intentionally allowing Have a large amount of Near Infrared to be processed through into our cells deeper in the body. It's amazing.

Nick Jikomes 50:10

You mentioned fire light earlier, can you talk a little bit more about how does the light spectrum of fire light compared to sunlight, or, you know, the light bulbs that people are gonna typically have in their home?

Scott Zimmerman 50:21

Well, like an incandescent ball of old, fire tends to have 10 to 15 to one near infrared, to visible contains, you know, some trace levels of blue. But it's almost predominantly in the near infrared. And that was always the problem with incandescent is that 90% of the spectrum that is being emitted by incandescent bulbs is in the near infrared, peeking up around one micron. And I would argue that, you know, people say, Well, I did fine under fluorescent, all that kind of stuff, but you came home to an incandescent lit room, you went to bed reading a story under an incandescent light. Now you don't you have a this thing that we're talking on, that contains zero near infrared, we have a big screen TV that's putting out tons of light at night, that has no near infrared component to it, you have, you know, all the windows are low E glass, which blocked the near infrared from coming into your building, or into your home.

Nick Jikomes 51:26

So when we when we talk about like LEDs, blue light versus incandescent light bulbs, the incandescent light bulbs emit more near infrared light. And is this I mean, is this, you know, a lot of people have an intuition for like, you know, they look different. You know, a lot of people say, I look bad under fluorescent lighting, or they say, I feel bad under fluorescent lighting. Is there more to it than just the light perception?

Scott Zimmerman 51:49

Absolutely, absolutely. I mean, I think that that that point, that's just a proven point. I mean, how much it degrades, there's certain people their study hour in Saudi Arabia, where they took various levels of depression, and they put them into a room with a fluorescent light versus a incandescent light. And depending on their level of depression that they had, their response was just skyrocketed. You know, and that's what I think that people that they were missing is that you or I may be fine. But there's at least a percentage of the population that is being affected. And even you and I are being affected in ways we don't really understand your, your your statement about, you know, it feels different. Is that anxiety? Well, we know that there's all these anxiety, you know, that we can alter hormone levels, you know, there's, there was a study done, where they looked at schizophrenic and clinically depressed individuals, and they measured the melatonin to cortisol ratios at midnight. Now, according to Ukrainian law, the melatonin should have been high and the circadian cortisol should have been low. What they found is there was a 4x difference between people who had schizophrenia, measured at midnight, that that showed that they had a much lower melatonin to cortisol ratio. And I would argue that based on our work, that's the same as saying a near infrared to visible ratio is a similar type effect. And so, you know, built into all this stuff is appears to be that the near infrared, and the longer wavelengths deep red is basically modulating how we feel neurologically as well as physically.

Nick Jikomes 53:41

Can you talk a little bit more about what's known about the relationship between light exposure and hormone production?

Scott Zimmerman 53:50

Well, like I say, I mean, if you look at the work, BYU number one, you have the the light exposure effects on the one side circadian, but then on the other side, the near infrared, you have that near infrared degenerating, high elevated laser levels of melatonin in the outer skin. You know, I like to say it's kind of, I guess

Nick Jikomes 54:15

people should know. So melatonin is itself I think, technically a hormone. That actually, yeah, yeah,

Scott Zimmerman 54:21

it's a hormone. It's also you know, you we also know that the longer wavelengths are affecting vitamin D production

Nick Jikomes 54:27

is a precursor to all the sex steroid hormones. Yeah,

Scott Zimmerman 54:31

I mean, if you look at the skin, the outer part of the skin generate can generate virtually every hormone in our body, in the outer part of the skin, especially the sex hormones, the steroid based things cortisol, vitamin D, they're easy. They not only can doing the precursor that goes to our glands to adrenal glands and things like that. But it's been shown that it can do it de novo. It doesn't need to do it. It has the ability to do it right on site and Think about it just from a evolutionary, all the actions occurring on the skin, you know, it's having to deal with a whole lot of stuff. And the ability to respond to that, you know, by the time you get around to, oh, I've got to something chewing on my arm that's causing me to bleed or whatever, by time, it goes all the way back to the brain through the land, the gland responds in some hormonal mass, in fact, systemically, it will be too late, and it'll be the appropriate amount. So instead, there appears to be this localization that occurs of generating various responses, you know, to the at the skin level. And it kind of like, it's kind of like, most of our medicine is our most of our medical stuff is from the inside out. This is from the outside in type thing.

Nick Jikomes 55:55

So in your home, in your own home