You probably think of the health effects of sunlight as a mixed bag. On the one hand, sun exposure helps your body make vitamin D. But on the other, it can cause skin cancer.

To get around this conundrum, dermatologists frequently recommend avoiding sun exposure when you can, slathering on sunscreen when you can’t, and taking a vitamin D supplement to make up for the lack of sunlight in your life.

Yet in seeking to solve one problem, this advice may open up many others and be contributing to ill health in the West.

Today on the show, Rowan Jacobsen, a science journalist who has spent years investigating the health impacts of sunlight, will unpack the underappreciated benefits of sun exposure, and that, crucially, they’re not primarily a function of the production of vitamin D and can’t be replaced with a pill. We talk about what else is at work in ultraviolet radiation’s positive effects on blood pressure, autoimmune diseases, insulin resistance, mood, and more. We also get into how to weigh these benefits against the risk of skin cancer, why health officials in Australia, which has the highest rate of skin cancer in the world, have changed their recommendations around sun exposure, and if there’s a role sunscreen should still play in your routine.

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Brett McKay: Brett McKay here, and welcome to another edition of the Art of Manliness podcast. You probably think of the health effects of sunlight as a mixed bag. On the one hand, sun exposure helps your body make vitamin D, but on the other, it can cause skin cancer. To get around this conundrum, dermatologists frequently recommend avoiding sun exposure when you can, slathering on sunscreen when you can’t, and taking a vitamin D supplement to make up for the lack of sunlight in your life. Yet, in seeking to solve one problem, this advice may open up many others and be contributing to ill health in the West.

Today on the show, Rowan Jacobsen, a science journalist who spent years investigating the health impacts of sunlight, will unpack the underappreciated benefits of sun exposure and that, crucially, they’re not primarily a function of the production of vitamin D and can’t be replaced with a pill. We talk about what else is at work, and ultraviolet radiation’s positive effects on blood pressure, autoimmune diseases, insulin resistance, mood, and more. We also get into how to weigh these benefits against the risk of skin cancer, why health officials in Australia, which has the highest rate of skin cancer in the world, have changed the recommendations around sun exposure, and if there’s a role sunscreen should still play in your routine. After the show’s over, check out our show notes at aom.is/sunlight. Rowan Jacobsen, welcome to the show.

Rowan Jacobsen: Hi, Brett. Thanks for having me.

Brett McKay: So you are a journalist, and for the past few years, you’ve been researching and writing about the benefits of sunlight to our health, and how the injunction to religiously slather on sunscreen might be causing unintended health consequences. Let’s talk about the health benefits of sunlight. I’m sure listeners have heard and know that sun exposure increases vitamin D levels in the body. How does that happen? What is it about sunlight that causes vitamin D levels to go up?

Rowan Jacobsen: Yeah, it’s kind of this interesting phenomenon where we really are photosynthesizing. We don’t do it like a plant does it, but we are synthesizing these compounds with the help of photons from the sun. So the way it works, so I guess for starters, vitamin D is a hormone that is used for all kinds of different reasons in the body. Like it’s kind of misnamed as a vitamin ’cause it’s not like the other vitamins, which are these little things that you get in food. It’s a hormone that we use for lots of different things and it’s essential to health and we mostly make it in our skin. And the way that evolution worked this process out is that it makes these molecules that are similar to cholesterol, they’re sterols, it makes these molecules that are like a couple of chemical processes, chemical steps away from becoming vitamin D and that’s as close as we can make on our own.

And we do that in the skin, and then what we rely on the sunlight to do is the sun hits those molecules, breaks open one of the little chemical bonds between the molecules so that that molecule can then change its form into a different form, which is vitamin D or actually pre-vitamin D. And then that molecule goes into the body and gets transformed into the type of vitamin D that we use after going through the liver and sometimes the kidneys too. So it’s this incredibly complicated process, but the upshot is that there’s this one step that we need sunlight to break open the bond for us so that we can change that molecule into something else.

Brett McKay: So I know sunlight is made up of different types of UV radiation, including UVA radiation and UVB radiation. Is there a specific type of radiation that causes that reaction?

Rowan Jacobsen: Yeah, for vitamin D, it’s all the UVB, which is particularly a narrow wavelength of UVB, about like 295 to 310, 315 nanometers. So yeah, there’s UVA, UVB, UVC. UVC gets filtered out by the atmosphere entirely, which is a good thing ’cause otherwise it would be really deadly. UVB is that next wavelength and then UVA has a very different size wavelength to it. And so we get both UVA and UVB on our skin. UVB is the one that can hit those molecules and break apart that bond and make vitamin D.

Brett McKay: What does our body do with vitamin D once it’s turned into vitamin D?

Rowan Jacobsen: So, most famously, it’s essential for bone mineralization. And this was discovered way back when kids were getting rickets in like… During the Industrial Revolution, suddenly, people who had always been outside farming were in these cities. The cities were really sooty, so even if you were outside in the city, you weren’t really getting any sunlight and the kids were working in factories. So suddenly, all the kids were getting rickets, which is when your bones are soft, too soft. They don’t get hard enough ’cause they don’t have enough calcium in them, and then you get these bowed legs. It’s bad. You don’t want to get rickets for sure. But a lot of kids were in the Industrial Revolution suddenly. And they figured out that that was because they weren’t getting proper bone mineralization.

They weren’t getting that calcium into their bones. And vitamin D does that. And that discovery was a huge health step forward because we were able to pretty much eliminate rickets famously because of cod liver oil. So cod liver oil is a good source of vitamin D. So they started giving the kids cod liver oil and that gave them just enough D to not get rickets. They also started putting babies in the sun. You know, like there’s these crazy photos from back in the day of these little cages hanging out the windows of tenement buildings, and you would put your baby in that cage for a little while just to get a little sunlight on the baby.

Brett McKay: That’s interesting. So people hear that, okay, I just need vitamin D. I don’t want to sit out in the sun ’cause I don’t want to get a sunburn. I don’t have time for that. I don’t want to get skin cancer. So I’ll just take a vitamin D supplement and that will take care of me and I’ll get all these benefits that come from vitamin D, one of them is just bone mineralization. And then there’s been these other health benefits that have been associated with vitamin D. So if you have elevated vitamin D levels, you have better metabolism, you reduce your cancer rates, things like that. So yeah, why not just take the vitamin D supplement?

Rowan Jacobsen: Yeah, right. And this is the message and the advice we’ve been receiving from dermatologists for a couple of decades now, is like, we know that sun exposure causes skin cancer. We know that it makes vitamin D, we know we need vitamin D. But no problem, avoid all sun exposure, and yeah, your body won’t make enough vitamin D, but you just take vitamin D pills to make up for that, and problem solved. So that was this overly simplistic understanding for a while. But to test it, what you have to do is do these trials where you get a lot of people so that you have some statistical power to get randomness out of there, and give half the people vitamin D pills and the other half just get a placebo and see what happens. And so now, some huge, huge trials have been done, multiple years, tens of thousands of people involved in the trials. And we have extremely strong definitive evidence that those vitamin D supplements do not help to improve any disease.

Just they totally failed in a way that… You know, science rarely gets results that are so definitive. Like there’s no question. They didn’t improve a single condition. Which was really surprising, because like you say, people who have high levels of vitamin D in their blood have lower rates of pretty much every disease you can think of. So we really did think, oh, vitamin D is not just for bones, it must be essential for all these other things in the human body and for preventing all these other diseases. So then these supplement trials, when they failed, then everyone had to kind of go back to the drawing board and say like, now wait a minute, how can it be that people who have naturally high levels of D in their blood have lower rates of all these diseases but if you artificially raise people’s amount of D in their blood with supplements, it doesn’t do anything? And you probably, you already know the answer.

Brett McKay: Right. Well, yeah, it’s the sunlight that’s doing it. Vitamin D is just a marker that you’re getting a sufficient amount of sunlight.

Rowan Jacobsen: Right, exactly. So it wasn’t causative, it was just correlation. The people with the lower rates of disease had a higher D because they were getting sun exposure, but now we know it wasn’t the D that was causing the lower rates of disease. It was something else about sun exposure.

Brett McKay: Okay. So people probably heard this idea that vitamin D improves a bunch of health conditions, but it turns out it’s not the vitamin D. There are other things going on, other pathways with the sunlight itself that creates those health effects. And we’re gonna talk about how the sunlight can improve those different facets of our health. That’s not to say that vitamin D is not important. You can get it from the sun or from a supplement. And as you said, we need vitamin D so we don’t get things like rickets. You don’t want rickets. So we need vitamin D for that.

Rowan Jacobsen: Yeah. And vitamin D is probably important in other ways. Like pretty much every cell in our body has vitamin D receptors in it, so they’re there for a reason. Like our cells are all doing things with D, but we only need so much probably. So you don’t wanna be vitamin D deficient. But this idea that really cranking up your level of D was gonna somehow chase all these diseases out of your body, that has turned out to be false. So D is important, but you probably get enough through sunlight, most of us. But it depends, like it depends where you’re living. So yeah, that’s only part of it. So could there be other things that sunlight is doing for you?

And now we have quite a bit of evidence that, yes, it turns out there’s dozens of different processes and pathways that are triggered by sunlight hitting skin that have lots and lots of different effects on the human body, and we’re really just learning about them. So this is the impasse. So now, the dermatologists are gonna have to readdress this whole formula that they gave to people. Like, don’t worry about the D, get the D through the supplement. Because it doesn’t work, and all those health benefits that we’re chasing, probably you need actual sunlight for that.

Brett McKay: Well, let’s talk about some of these health benefits that people are starting to see there’s a connection to sunlight. One of them is blood pressure. There’s a connection between increased amounts of sunlight exposure and decreased blood pressure. And there’s a guy, it’s a dermatologist who found this connection, a guy named Richard Weller. Tell us about him. What’s the connection between sunlight and blood pressure?

Rowan Jacobsen: So he’s a fascinating guy, a dermatologist in Scotland, but he does work in Ethiopia every year and has for decades. And he started questioning the conventional wisdom on sun exposure and vitamin D after doing all this work in Ethiopia. Where Ethiopia, like huge amount of sun ’cause it’s in the tropical zone, in the equatorial zone and it’s up at like 6,000 feet. So it gets a huge amount of sunlight. And he says he never treated a skin cancer there, never saw any ’cause he was treating people with very dark skin and they just weren’t coming down with skin cancers. So that was the first step where he started questioning some of the conventional wisdom. But then in terms of blood pressure that we had known for a long time in these observational studies that people living in areas that got more sun exposure had lower blood pressure. Like high latitudes, where you don’t get as much sunlight, higher blood pressure.

And everyone had sort said like, well, it’s probably just temperature, because your blood pressure is definitely lower in warmer temperature areas. So everyone kind of like chalked it up to temperature. But then, back, I don’t know, in the early 2000s, I think it was, some scientists discovered that… Actually it was earlier than that, scientists discovered that nitric oxide, which is a very simple molecule, is actually a really important signaling molecule in the body, and that nitric oxide will cause the muscles in blood vessels to relax and to dilate. So nitric oxide is a really potent vasodilator, so it will expand those blood vessels and lower blood pressure. And that was, a guy won a Nobel Prize for that back in the ’90s I think. But what people only realized more recently and what Richard Weller’s research helped to show was that our skin actually has these huge stores of nitrates in them, which is sort of a precursor to nitric oxide.

And when sunlight hits skin, it breaks up those nitrates into nitric oxide and sends them into the body and lowers blood pressure. And he did these experiments on his grad students. Like first they showed it in mice and they’re like, huh, it works. And then he did experiments on grad students where he shone UVA. He wanted to prove it wasn’t vitamin D that was responsible for this ’cause everybody chalks up everything about sunlight to vitamin D. So he used UVA instead of UVB ’cause UVA light does not create vitamin D. So he took his grad students and shone UVA light on their arms and he also put foil, like metal foil on half the students so that they were getting the heat of the UVA but not the actual beams of the UVA ’cause he wanted to prove that it wasn’t just heat either, ’cause we know heat can lower blood pressure.

And sure enough, the students who got the actual raise of UVA light, their blood pressure went down more than the students who just got the heat. And they’ve since done other studies looking at huge chunks of people in both the US and UK. And yeah, it’s now very clear that sun hitting skin produces nitric oxide, which lowers your blood pressure. And blood pressure is the number one risk factor for lost years of life and mortality worldwide. So anything that lowers blood pressure can be a pretty big deal.

Brett McKay: And that’s a cheap intervention. It’s free.

Rowan Jacobsen: Yeah, it is. It’s free. You know, it’s a cost benefit ratio ’cause when you’re exposing yourself to light, you are raising your risk of skin cancer. But skin cancer kills very few people. It’s a very, very small factor in mortality, and blood pressure and all the cardiovascular related diseases is number one cause of mortality in the world. So yeah, it’s probably a very good benefit for the risk.

Brett McKay: Yeah, we’re gonna talk more about the real risk of skin cancer later, but with these blood pressure experiments, it was UVA radiation that produces nitric oxide?

Rowan Jacobsen: Yeah, well, so he used UVA ’cause he wanted to prove it wasn’t related to vitamin D. But since then, I think they’ve found that UVB does it too. Like all the UV produces nitric oxide. So yeah, so the blood pressure lowering effect is, and I don’t even like dividing it up too much ’cause anytime we start to boil it down to this sort of human created simplicity, it reminds me of like fat carbs of protein. It’s like this human construct that turns out to be much simpler than the real thing.

Brett McKay: So sunlight can reduce blood pressure. There’s also been research showing that sunlight can strengthen immune function or improve immune function. Can you tell us about that research?

Rowan Jacobsen: Yeah, and that’s really fascinating to me. And that research was one of the main reasons the Australian authorities decided to revise their sun exposure recommendations. But this is, again, is something that’s been known for a while. We’ve got 20 or 30 years of research on this and it’s just… In science, department A is not necessarily talking to department B. So the immunologists were way down this path of researching sunlight’s effect on the immune system, and the dermatologists were just not ever getting the message on the other side of the campus. But anyway, so what we know is that we have a lot of immune cells in our skin, which makes sense ’cause the skin is the first barrier to the outer world. So the skin is constantly dealing with pathogens and cuts and all kinds of assaults to the body. So there’s constant immune action happening in the skin. And UV is another sort of minor assault that we get every day, that we’ve been getting every day for as long as humans have been humans.

So the skin has evolved to deal with it. So it gets a little dose of UV and then it heals that damage and healing that damage is basically an anti-inflammatory response. So the UV is a tiny bit of inflammation and it triggers an anti-inflammatory response in the skin. All these immune cells get created, they reduce inflammation, but then what’s really interesting, which is a more recent discovery, is those cells then migrate from the skin into the body through the lymph nodes and reduce inflammation throughout the body. So it’s the systemic anti-inflammatory response that’s triggered by a little bit of UV. And that’s important, because one thing we’re learning more and more is that a lot of the classic diseases of modern civilization have roots in inflammation. Like we sort of have a lot of chronic inflammation going on all the time. So something, and again, like you said before, a free intervention that can reduce inflammation could be a fantastic health benefit.

Brett McKay: And I feel like we intuitively understood this maybe a century ago. I love reading these old history books, biographies, and there’s always this instance where some famous guy gets sick as a kid and the doctor’s like, “Well, you need to take them out to the desert,” or “Go to the the ocean side and get lots of sun, because you got tuberculosis and that will help heal you.” And I think that just spending time in the sun probably did a lot that helped strengthen their immune system.

Rowan Jacobsen: Yeah, exactly. There was this whole age of heliotherapy where, like you said, tuberculosis, rickets of course, and some other diseases, psoriasis. People would be sent out into the sun, or they’d be sent up into the mountains in Switzerland to cure these diseases. And it worked. They didn’t quite understand why it worked, but it was somewhat successful. So sun was definitely considered by the leading doctors to be a benefit to health. And then that all started to flip in the ’30s and ’40s as everyone realized, they discovered the mechanisms by which UV can cause skin cancer. And then slowly, decade by decade, the message, that sort of the drumbeat got stronger and stronger, stay out of the sun so you don’t get skin cancer. And we’re kind of at this like peak moment of that.

Brett McKay: Another way sunlight can improve your immune function, you know, vitamin D, again, vitamin D plays a role in your immune system. If you get sunlight, you’re gonna increase your levels of vitamin D, which also contributes to your immune system.

Rowan Jacobsen: Exactly. And yeah, that’s an important point. All of these pathways are probably way more complicated than we think. It’s not gonna be one very simple step by step, like this, to this, to this. A whole lot of stuff happens when sun hits skin, and all these signaling molecules and hormones, they don’t necessarily just do one thing. In different situations they’ll do different things. You’ve got this very complex effect happening with nitric oxide, which can also be anti… It can be used to kill pathogens. So you’ve got nitric oxide, you’ve got vitamin D, you’ve got these direct effects on immune cells.

And one of the other things, like vitamin D, we’re all told to take vitamin D pills, that’s because everybody thought there was just one type of vitamin D, and most dermatologists today still think that. But one of the things we’ve learned in the past 10 years is that there are more probably like 20 different, slightly different versions of vitamin D that the body makes with sunlight. And they all have slightly different side chains on these molecules, but they all do slightly different things and we really don’t understand how that works. But we do know that a bunch of those non-canonical types of vitamin D, you can’t replace those with a pill that is going into the stomach and then to the liver. It just doesn’t work. It will not make these other flavors of vitamin D.

Brett McKay: Related to the immune system, there’s also been research showing that sunlight exposure can help with autoimmune diseases. So this is when your immune system goes haywire and starts attacking your body. So things like psoriasis is an autoimmune disease, arthritis, rheumatoid arthritis, MS is another disease like that. But sunlight seems to help with those conditions.

Rowan Jacobsen: Yeah, for sure. Again, it’s that anti-inflammatory effect. And it’s really strong with MS, which is a disease where the body’s immune system starts attacking the sheaths around the nerves that protect the nerves so that signals can be sent, electrical signals can be sent. The body mistakes the little sheaths around those nerves for an invader and starts attacking them. It’s just this classic but like overreaction of the immune system. And sun exposure really effectively slows down that process for MS. Like you look at the observational studies based on latitude and sun exposure and people living at high latitudes have usually several times the risk of MS compared to people living at lower latitudes. And prevalence is higher in winter than in summer, and it’s also, you can even track it with birth month where people born in spring, at the end of like a long winter, have higher rates than people born in early fall.

Same thing for psoriasis, type 1 diabetes, like you said, and some other autoimmune diseases. And there’s some clinical trials going on right now where they’re tracking this. Because basically this has mostly been observational studies, so you really, in order to prove it, to really have like the gold standard of evidence, you need to have some clinical trials where you’ve shown that it works. But we do know from some early clinical trials that just a little bit of narrow band UVB therapy, so using a light that only shines UVB in this very narrow wavelength that doesn’t cause skin cancer, it reduces all the biomarkers of inflammation in the blood of these patients that have MS and other things. So yeah, it looks good so far for that.

Brett McKay: That’s really interesting. What about insulin resistance, does sunlight affect that? That’s a big problem these days.

Rowan Jacobsen: Huge. Huge. Yeah. Insulin resistance, diabetes, all the… Like the metabolic syndrome stuff, where your body’s not metabolizing very actively, it’s just sort of slowed down, getting a little groggy and your cells aren’t accepting… They’re resisting insulin. Yes, sunlight has been shown in studies of both mice and observational studies of people to have a pretty solid impact on reducing risk of diabetes and insulin resistance. And in terms of why, like it’s probably some of those same things we’ve been talking about. I think there’s probably an inflammatory component to diabetes and insulin resistance as well, and so this probably reduces that a little bit. But then the other part of it, and I think you can apply this to a lot of things we’ve been talking about, if you wanna like pull back and think about big picture, there’s this really fascinating study a few years ago that looked at all the genes in the human body and when they were being expressed.

So then when they were being cranked up and when they were being kind of turned off, in terms of like month of the year. And what they found was that about a third of the genes in the body have a seasonal component. So they’re either being cranked up in summer or in winter. And generally, what they saw was that the inflammatory genes were being cranked up in winter and anti in summer. So winter, like evolutionary, the theory would be that in winter that’s when flu and all these other infectious diseases are on the rampage. We’re spending a lot of time cooped up together in spaces where we’re more likely to share diseases with each other. Summer is a low disease time, so it makes sense in winter to crank up your inflammatory genes to deal with all these pathogens and to basically try to just survive winter.

 And then summer, things are good, you’re out in the open air, you can reduce all that inflammation. But of course the signal for that is, one of them is sun hitting skin, sun hitting skin and sun hitting retinas. So if we are living our lives indoors and aren’t getting exposure outside, our bodies might be in a sense thinking that it’s biological winter all the time. So they’re acting like it’s biological winter, so they’re staying in this inflammatory state. So that would be the theory underlying why this would be the case, but it’s just a theory right now.

Brett McKay: We’re gonna take a quick break for a word from our sponsors. And now back to the show.

What about sun exposure and its connection to sleep and mood?

Rowan Jacobsen: That one is for sure, like no question and nobody even argues with this one. And it’s through different mechanisms. It’s probably partly through the skin, but a lot of it is through the eyes. But yeah, we know for sure that getting that hit of light in the morning is what sets your circadian rhythm, sets your biological clock, tells you that it’s morning, it’s time to crank up your system and be really active and high functioning. So if you’re outside in the morning and you’re getting a lot of bright light, then that melatonin that your body makes that’s for sleeping at night will quickly get reduced and you’ll get alert for your day, and then also you’re on the schedule where at night the body will know to turn up the melatonin so that you sleep well.

And when you don’t get that strong, diurnal change in light, then your circadian rhythms can get messed up. And you can’t get it being indoors, it’s interesting. I didn’t start paying attention to this until I was reading some of these researchers who specialize in this stuff. But even a cloudy day outside is way brighter than with your lights on indoors. Not even close, by like 50 times, 100 times, in terms of lumens. So you really need to be outside to get that signal that tells your body to wake up and sort of crank up the whole system and then the opposite at night.

Brett McKay: And the connection to the mood, people probably are aware of seasonal affective disorder. It happens during the winter. There’s less sunlight exposure, so people kind of get in the funk. You’re probably familiar with this, you live in Vermont.

Rowan Jacobsen: Totally.

Brett McKay: Vermont falls and winter. I remember we lived in Vermont, my wife and I, shortly after I graduated from law school, we were there in the fall. And I remember it was like 4 o’clock in the afternoon, it’s dark. I’m like, what? It’s 4 o’clock. Why is it…

Rowan Jacobsen: Yeah, it’s depressing.

Brett McKay: It got depressing.

Rowan Jacobsen: It does. And you can fight it, right? You go out, you ski, you do whatever you can to embrace the day. But it’s still, it’s not that natural an environment for human beings at some level. So you got to figure out ways to get around that. And yeah, people do. Yeah, their hormones are strongly affected by that. So again, you kind of go into hibernation mode. It’s kind of like what we were talking about earlier. All that darkness is a signal to the body to just shut down and endure. ‘Cause normally, in winter, food is often tight. Like before all our modern conveniences, you really did want to sort of put the system on minimal mode until things got better. So I think we still are dealing with that. So the best thing and the way to fight it is either, like you can have artificial lights that are bright enough that they can affect that SAD, or you go outside as much as possible or you go on vacation.

Brett McKay: Yeah. So yeah, I saw some research that sunlight can increase levels of serotonin, which is a feel good neurotransmitter, releases endorphins that can also help you feel high and euphoric.

Rowan Jacobsen: Totally.

Brett McKay: I mean, if anyone’s been to the beach or on a hot sunny day, you just feel good, you just feel so groovy whenever you catch some rays.

Rowan Jacobsen: Yeah, and it’s direct, like your skin and brain are producing endorphins, are producing dopamine. Dermatologists talk about how unfortunate it is that people get addicted to sunlight because of these things, but it’s like, well, there’s a reason. Your body isn’t just making those on a whim, there’s a reason. So you don’t want to get too much, but you do want to at least pay attention to those natural signals that we have.

Brett McKay: Okay, so I think we’ve talked a lot about the health benefits of sunlight. Increases vitamin D, but vitamin D, what we talked about is not necessarily connected to all these other health benefits, like reduced blood pressure, reduced metabolic syndrome, etcetera. That is from sunlight itself. Vitamin D is just a marker that you’re getting enough sunlight. And people might be hearing this thing, oh, okay, yeah, I’ll grant you that there’s all these health benefits that come with sunlight, but we know for a fact that it frequently causes skin cancer. So why risk the exposure to get those benefits? Just put on the sunscreen.

And that’s the stance, we’ve talked about this throughout this conversation, that’s the stance the American Academy of Dermatology has taken, which says you should apply sunscreen every day on skin not covered by clothing if you will be outside. And I think this is interesting ’cause I’m 41, so if you’re my age, sunscreen really wasn’t a big thing when I was growing up. Maybe my mom would say, “Well, you’re gonna go to the water park all day, put on some sunscreen.” But I don’t remember putting sunscreen on that much when I was a kid. So when did this message to always wear sunscreen arise? What was behind it?

Rowan Jacobsen: Yeah, and so what was behind it was simply that one fact that we know that UV exposure triggers skin cancer, raises your risk of skin cancer. So based on that one thing is why we’ve been told to, continually to keep reducing our amount of sun exposure to basically zero now. Or let me add, skin cancer, also wrinkles, sunspots, like there’s this cosmetic stuff, the cosmetic damage that UV causes as well. But in terms of health, then skin cancer is the one thing that you have to worry about. And yeah, it’s interesting that the message has gotten more and more strident with each decade. And people have been using more and more sunscreen with each decade. But skin cancer rates are higher than ever. So the etiology is probably more complicated than they think, but it is definitely very well established that sun exposure causes skin cancer.

But in terms of what you wanna do about it, it’s not clear that a little bit of sun exposure is really that problematic. And there’s quite good evidence that there are more benefits than risks for that small amount of sun exposure. So then it’s a question of like, where do you set the… You know, the pendulum’s swung way far, as far as it could in one direction where, I don’t know, if you look at a lot of the recommendations in popular magazines and newspapers, the dermatologists are literally saying, even in winter, on a cloudy day, if you’re gonna be indoors all day, still put on sunscreen. There’s no science behind that. They’re just trying to get people into the habit of doing it. And I think the worry is that people aren’t very good at following directions. So if you want them to put on any sunscreen, you gotta tell them to put on a lot all of the time and hope that they’ll listen to you one out of every three times or something.

Brett McKay: In your articles, you talked about that the conversation about skin cancer is a lot nuanced. I think people hear cancer and they just think, okay, cancer equals death automatically. And they probably think melanoma when they think skin cancer. But there’s different types of skin cancer. Melanoma is the worst one you could get. But the stuff that’s often caused by sun damage, it’s like basal cell carcinoma. Those are actually pretty treatable. Like you can actually just go to a dermatologist and it’s like an outpatient surgery.

Rowan Jacobsen: Yeah, that’s correct. There’s three different kinds of cancers that are the main ones, basal cell carcinoma, squamous cell carcinoma, and melanoma. And basal cell carcinoma is by far the most common cancer in the world. It’s probably more common than every other cancer put together. That’s the one, you know, you always see these public service warnings, like one in every three people will get skin cancer. And that’s what they’re talking about, is basal cell carcinoma. It doesn’t actually really have any health impacts 99.9% of the time. That’s the one, yeah, you go in, you get a cutoff, you’re done. So in a way, it would be better if it wasn’t called cancer, ’cause like you were saying, that word really scares people. Richard Weller, the dermatologist we mentioned, he actually told me that when one of his patients comes in and he diagnoses a BCC on them, he then says, “Congratulations ’cause your life expectancy just went up.”

And what that means, that doesn’t mean BCCs are actually good for you. It means the people who are getting BCCs tend to be quite healthy, because it’s like your dad who’s playing golf in Florida every day. He’s getting sun exposure, he’s getting a lot of exercise, he’s getting BCCs, but he’s quite healthy. So yeah, Richard Weller says he cuts a lot of BCCs off a lot of very healthy old people. SCCs, squamous cell carcinomas, are a little bit more to worry about than BCCs. But again, usually it’s just cut it off, outpatient procedure, that’s it. Melanoma is the one that kills people and that’s the one you need to worry about, but it’s much, much less common than the other two. It’s like 1 to 2% of skin cancers are melanoma, and the rest are BCCs and SCCs. So there’s a little bit of a bait and switch that you see in the public messaging where people will say, skin cancer is incredibly common, one out of three people will get it.

And then they’ll say, melanoma kills 10% of the people who get it. And if you don’t look carefully, you’ll think that skin cancer is both extremely common and extremely deadly, but it’s not. There are some that are extremely common and are no big deal and there’s one, melanoma, that can be deadly, but it’s uncommon. And BCCs, definitely caused by sun exposure. The more sun exposure you get, the more BCCs you’ll get. Melanoma, it’s a different story. It’s not as simple as just chronic sun exposure. Melanoma tends to turn up in people who get intermittent sun exposure. People who have pale skin and basically go to Cancún on vacation and get fried, that’s kind of like the perfect formula for melanoma. And worst thing of all, probably for you and me, it’s mostly associated with sunburns in childhood and adolescence, so.

Brett McKay: I had some sunburns, some really bad ones.

Rowan Jacobsen: Me too. I grew up in Florida. And so a 13-year-old kid growing up in Florida is gonna get a fair amount of sun.

Brett McKay: Yeah, I had one, I had a few where like your skin just peels like paper.

Rowan Jacobsen: Yeah.

Brett McKay: It hurt. But then when it peels, that was kind of satisfying.

Rowan Jacobsen: And it’s just so weird. It’s kind of fun. But it’s not good for you. They definitely, like every researcher I’ve talked to across the board says, just don’t burn. Burns are bad.

Brett McKay: So one of the arguments you’re making in your articles and in your research is that this sunscreen absolutism that we have in the United States, where it’s like you gotta apply sunscreen, even if you just go outside for a little bit, just all the time, even in winter time. What it’s doing, yeah, we might be staving off these skin cancers like basal cell carcinoma, but those, it’s not gonna kill you. You can get just the surgery to take it off, but we’re missing out on those other health benefits that come from sun exposure. ‘Cause when you block the sun with sunscreen, you’re missing out on the vitamin D production, the reduction in blood pressure, immune system improvement, etcetera.

Rowan Jacobsen: Yeah, possibly. It depends on the sunscreen. And this is one of the interesting nuances here I think, is back when sunscreen was SPF 15 or whatever, it doesn’t block 100%. It blocks maybe like 90%. So there’s still about 10% getting through. And so maybe, like on a day at the beach, that might have actually been the perfect formula, where that sunscreen was letting you get a great amount of UV but was still preventing you from getting burned. So now of course we’ve got SPF 50 or even SPF 100 sunscreens, and the advice is even on a cloudy winter day, put it on. So there’s this real push to make sure that people never, never get any photons hitting their skin. So that’s probably gonna have to change. But I actually think sunscreen can be an ally in making sure you do get the right amount of sun. ‘Cause if it gets you outside without burning, it could actually be a benefit.

Brett McKay: Something you mentioned in one of your articles, this sunscreen absolutism. The dermatologists, they don’t discriminate on your melanin level. So even if you’re Black or Hispanic, where you have a lot of melanin and you don’t burn as easily, they still say, yeah, you gotta wear a SPF 50 sunscreen. And you’re like, well, that doesn’t make sense.

Rowan Jacobsen: Right. And this is the thing that’s gonna have to change I think, and I think probably pretty soon. That advice to always put on heavy duty sunscreen every day, indoors or outdoors, that’s probably not a bad recommendation for people with the very palest skin. Like people who have red hair, freckles, who evolved, their ancestors came from places at very high latitudes that were getting very little sunlight and kind of evolved skin to harvest whatever light they could get. Like people who never tan always burn, that advice makes sense for them, but not for everyone else. And the world is mostly populated by everyone else.

So people with really dark skin, on the other end of the spectrum, basically do not get skin cancers from sun exposure, do not have any of these risks. But also have, because they have more natural sunscreen basically, need more sun in order to produce vitamin D and some of these other compounds. So for them, the recommendations make no sense. And then there’s a bunch of people in the middle who have maybe more of like a Mediterranean skin tone, an Asian skin tone, who have a little bit more risk of skin cancer than people with super dark skin, but really very little. And also probably have a lot to gain from moderate sun exposure. And you don’t need, that’s the other thing we should probably talk about, you don’t need too much to get some of these benefits.

Brett McKay: We’ll talk about the daily recommended dose of sunlight here in a bit. So in America we have a very, you call it sunscreen absolutism. No matter what, how you spend your time, whether indoors or outdoors, whether you’re pale, dark, wear sunscreen, health officials in Australia have taken a different tack, they’ve gotten more nuanced with sunscreen use. And this is interesting ’cause Australia is a place that has notoriously high levels of UV exposure and skin cancer, but health officials in Australia are saying maybe you don’t use sunscreen all the time. So what are they recommending?

Rowan Jacobsen: Yeah, and it’s so funny, because probably the last place on earth, you would expect to be the first place to take the plunge on changing the recommendations would have been Australia. ‘Cause as you say, their skin cancer numbers are off the charts, the highest in the world, like more than twice as high as US or UK. And it’s because they have predominantly pale skin population in an extremely sunny place. So it’s a really bad match. So they get tons of skin cancer, but they also have some of the longest lived people on the planet. So right there, it tells you that maybe like sun exposure isn’t so bad for you, even if you do have pale skin.

So Australia, I think the reason that they ended up being the first ones to change, to go away from the zero sun policy is because they’ve had to deal with this. Like melanoma and skin cancer is in their face every day, they’ve had to like process it the most. So maybe they’re a little less scared of it in a sense. And I think it was more obvious to them, ’cause they do a lot of research on it. They have a lot of the top skin cancer researchers in the world. And they can see that a lot of people were clearly getting more harm than benefit from this zero sun policy. They’re also saying that there was a lot more vitamin D deficiency in Australia than they would ever expect for such a sunny place.

So they actually started worrying that people had taken the message to heart maybe too much. So they wanted to change their messaging so that it was no longer this one size fits all message that should only have applied to people with super pale skin. And they kind of broke up their messaging into three groups, people with pale skin, people with dark skin, and then people in the middle, and different recommendations for each one. Pale skin, yeah, still use your sunscreen all the time pretty much. But when the sun’s not so bright, try to at least get outside with sunscreen on to get whatever… They were focusing on D, but they know it’s this other stuff too, to get whatever sun you can.

Middle group, get small amounts, still use sunscreen anytime the sun is pretty bright. But yeah, work the edges of the day, the edges of the season and make sure you are getting some direct exposure. And then people with dark skin, they basically said like, you just should focus on getting lots of sun. You don’t need sunscreen except when you’re gonna be outside for an extended period on a bright day. So that was quite controversial. And they caught a little bit of hell for it, but I think they’ll turn out to be the first penguin in the water and then all the other penguins will start to join them.

Brett McKay: Are you seeing a shift happen amongst American dermatologists yet?

Rowan Jacobsen: No. So far, none. UK, yes. UK is starting to shift a little bit, Europe a little bit. America is gonna be last on this for whatever reason. It’s just kind of how we do things, I think.

Brett McKay: Yeah. So let’s talk about how we can get sun exposure without increasing the risk of skin cancer. ‘Cause some people might hear this news that, okay, sunlight is great for you. I’m just gonna get sun all the time and never wear sunscreen. That’s not what these health officials in Australia are advocating for. So based on the conversations you’ve had and the research you’ve done, how can we get sun exposure and get all these health benefits without increasing our chances of getting different types of skin cancer?

Rowan Jacobsen: Yeah. And this, I’m quite sympathetic with the dermatologists because, yeah, you tell people that 10 minutes of sun is good for them, and sure enough some of them will go out there and get six hours of sun. ‘Cause they’re like, if a little’s good, then a lot’s better, right? So that is definitely something worth worrying about. But I feel like you just have to give the straight information, right? And then hopefully it’s clear enough that people can follow it. So Australia, when they put out their new position statement, they actually have all these tables in the back. It’s worth looking at that document that they created.

And the tables show for places with different UV indexes, so that’s gonna depend on where you are in the globe and what season it is and the day, right? For your skin type and UV index, how many minutes of exposed sunlight do you need to get a healthy vitamin D dose? So those will translate to the US too. So those are worth checking out. But what it comes down to is, for most people on most days, you’re either gonna get it just walking about your day, or you can get it with 10 minutes or to 20 minutes of focused exposure.

Brett McKay: Yeah. And if you have darker skin, you might have to extend the amount of time you’re out there getting that sun exposure to get the benefits.

Rowan Jacobsen: Quite a bit. And the other part of it, though, is that in higher latitude places, like here in Vermont, we don’t get any UVB. All the UVB is filtered by the atmosphere like November through March, probably. There’s just too much atmosphere that the sun is coming through at that low angle. So we don’t get any UVB for four months of the year. And you can save, your body will save it up a little bit, but that’s where you see a lot of vitamin D deficiencies, is at higher latitude, colder places.

Brett McKay: All right. So those Australian tables are a good place to check to see how much sun exposure you should get each day and in each season, ’cause it’s gonna differ, and then when to use sunscreen. But in general, what are some good general guidelines for using sunscreen? Because you’re not… I mean, even though you’re against sunscreen absolutism, you’re not against sunscreen altogether. So when should people put on sunscreen?

Rowan Jacobsen: Anytime you think you might be out long enough to get a burn, and as I think you and I can both attest to, it’s easier to get a burn than you think. Like you think, oh, I’m not gonna get burned, and then you get burned. It’s easy to just get a little more than you think you’re gonna get. So it makes sense to play it cautious and use it anytime you know you’re gonna be out for a while. And unless it’s like, you know, if it’s winter, that’s a whole different deal.

Brett McKay: Yeah, all the dermatologists you’ve talked to who are sort of pro getting sunlight and not using sunscreen all the time, they all agreed you do not want to get sunburned. Like you want to avoid sunburn as much as possible ’cause that’s what caused all those problems.

Rowan Jacobsen: Yeah, that’s just your skin cells dying and freaking out, and yeah.

Brett McKay: Yeah. So for me, I work from home. I typically don’t wear sunscreen at all ’cause I’ll just go outside, get some sun when I’m doing my early morning walks, doing chores and errands. I will wear sunscreen when I’m gonna be out for a long time, especially if I’m gonna be at altitude. So like my wife and I just went backpacking, I slather on the sunscreen. It’s so easy to get sunburned when you’re up in the mountains at 10,000, 11,000, 12,000 feet, ’cause you don’t have the atmosphere filtering the radiation.

Rowan Jacobsen: Yeah, for sure.

Brett McKay: So constantly applying sunscreen then and then when I’m skiing, ’cause like the sun reflects off the snow, and it’s easy to get sunburned. And it’s hard there ’cause you think it’s cold, so you really can’t feel anything, but you go in and your cheeks are red, and you’re like, ah, didn’t put on enough sunscreen.

Rowan Jacobsen: Yeah, for sure. Yeah, totally. All those things. And yeah, also anytime it’s gonna help you get outside, because one of the criticisms that people get in these observational studies where it’s like, oh, these people who are getting all the sun exposure are healthier in all these ways, and they have better longevity, blah, blah, blah. And one criticism will be, well, but how can you tell it’s the sun exposure? Maybe there’s just things about being outside, they’re exercising. Like, in those studies, you always try to control for exercise, so you’re comparing people who are exercising the same amount. But still, there could be other things about being outside that are just good for you. So, I don’t see the problem in that if the answer is get outside, right? So if sunscreen is gonna help you spend less time indoors, then I think it’s all to the better.

Brett McKay: Is anyone exploring, I don’t know, special sunscreens or ways people can get the benefits of sunlight without raising their risk of skin cancer?

Rowan Jacobsen: What people are doing is there’s a lot of experiments using these narrowband UVB lamps that a couple of companies are making now. I think this is gonna become a big deal. So they were first used for psoriasis treatment I think, and they just produce a very narrow band of UV, somewhere around like 300, 310 nanometers. It’s been used in psoriasis patients for a long time, decades, and we know it does not cause skin cancer. It’s not the type of wavelength that damages DNA. But it does produce vitamin D, and it also seems to have these good immunological effects.

Like psoriasis is an autoimmune disease where your skin is being attacked by the immune system, and it definitely has an excellent effect on psoriasis. It seems to work for MS. It even worked for COVID, it seems like, maybe. So I think you’re gonna see a lot more people using UVB, so then there’s not even an issue with skin cancer. But I’m still not convinced that you get all the benefits from UVB lamps that you would get from sunlight.

Brett McKay: Here’s a controversial question. Tanning beds. Can you get the benefits of sunlight from a tanning bed?

Rowan Jacobsen: Yeah, that’s an interesting one. I don’t know the answer yet. That’s why I’m working on a book about all this. It’ll be out in a couple of years by the time I’ve done all the research, written the manuscript, and then gone through the production process. But I’ll definitely have a chapter on tanning beds in there. Right now, I don’t know enough. I do know, like tanning beds do raise your risk of skin cancer, so dermatologists are strongly anti-tanning bed. But they do definitely give you some of the benefits, especially the endorphins, for sure. They give you that hit of feeling good. They will improve your vitamin D a little bit. But again, because it’s not the same as sunlight, I’m somewhat skeptical of them, but I don’t know enough to say whether they’re just plain bad or whether they might have a use.

Brett McKay: Yeah, a few years ago here in Oklahoma, we had a winter where it was just gray every day for like two months. And I was getting pretty depressed. I was getting some seasonal affective disorder. I got brown skin. I’m swarthy. So I need a lot of sunlight to get the benefits. And my wife said, you should just go to a tanning bed. And I’m like, tan? I’ve never done that before. That’s like what they do on Jersey Shore. Like I’m not gonna… And so I did it, I did like the least amount. So I did the least amount of time. I think it was just like two minutes. I mean, it was really short. And I felt better afterwards.

Rowan Jacobsen: Totally, yeah. I have friends who do it, and same thing.

Brett McKay: Yeah, I’d be interested to see if instead of tanning bed salons, you have UVB light salons, where you stand in front of a UVB light instead of going to a tanning bed to get the health benefits of sunlight.

Rowan Jacobsen: Yeah, I’m curious too. And I suspect that the tanning beds are gonna go in that direction, whether it’s more than just the UVB or just the UVB. But I bet they’re gonna try to curate their wavelengths a little bit to try to maximize the good and avoid the bad. That’s just a guess.

Brett McKay: Well, Rowan, this has been a great conversation. Is there someplace people can go to learn more about your work?

Rowan Jacobsen: For me, it would be rowanjacobsen.com.

Brett McKay: Rowanjacobsen.com. And then look out for the book you’ve got coming out.

Rowan Jacobsen: Yeah, In Defense of Sunlight, 2026.

Brett McKay: 2026.

Rowan Jacobsen: I think that’s safe. Safe prediction.

Brett McKay: And in the meantime, if you’re listening, go out and get some sun. You’re a plant. That’s one of the cool takeaways. I forget, like we’re little plants. We need water and we need sun. So get some sun.

Rowan Jacobsen: We photosynthesize, yeah.

Brett McKay: Yeah. Well, Rowan Jacobsen, thanks for your time. It’s been a pleasure.

Rowan Jacobsen: Thanks. It was great being here.

Brett McKay: My guest today was Rowan Jacobsen. You can find more information about his work at his website, rowanjacobsen.com. Also check out our show notes at aom.is/sunlight, where you can find links to resources, and we delve deeper into this topic.

Well, that wraps up another edition of the AOM podcast. Make sure to check out our website at artofmanliness.com where you can find our podcast archives. And while you’re there, sign up for our newsletter. We got a daily option, and a weekly option. They’re both free. It’s the best way to stay on top of what’s going on at AOM. And if you haven’t done so already, I’d appreciate it if you take one minute to give us a rating on Apple Podcast or Spotify. It helps out a lot. And if you’ve done that already, thank you. Please consider sharing the show with a friend or family member who you think would get something out of it. As always, thank you for the continued support. Until next time, this is Brett McKay, reminding you to not only listen to AOM podcast, but put what you’ve heard into action.