[drob518]

I think we’re starting to find that the “if you get sunlight you will develop skin cancer” mantra is way overblown, if not outright wrong. Being out in the sun is good for humans. In fact, we need it. But modern life largely conspires to prevent it for most of the developed world. Even when we do, we slather ourselves with sunscreen that might be doing more harm than good. Better to wear long sleeves and a hat that you can take off and at least get reflected sunlight while wearing. Oddly, it turns out that our bodies have been tuned to survive outside. Whodathunkit?

[chongli]

Here’s my hypothesis: it’s not total sun exposure that causes issues, it’s inconsistent sun exposure. Those of us in northern climates experience an annual cycle of very high and then nonexistent sun exposure. This causes our skin to stop producing melanin during the winter and then leaves us vulnerable to sunburn in the spring and summer. If we had year-round sun then our skin would consistently maintain melanin levels and we wouldn’t have sunburn.

I’d love to know if there are any studies trying to answer my question.

[dgfl]

This is precisely the picture that I seemed to get when looking at this in depth some time ago. Most meta-reviews highlight a correlation between _number of blistering sunburns_ and melanoma. Not between actual amount of UV exposure. You may think that they’re the same, but they’re not. In fact, the same meta-review was noticing weak anti-correlation between chronic sun exposure and melanoma, I.e. people who work outside shirtless actually have better odds than baseline.

Most risk seems to come from occasional exposure to extremely strong sunlight compared to your day-to-day baseline. Practically speaking, if your skin is able to tan, absorbing as much sunlight as your environment allows for most of the year, with the intrinsic gradual build-up over spring, should be harmless if not even beneficial.

Of course, this highly depends on your genetics and your location. Avoid sunbathing around the equator regardless. And if you’re physically unable to tan, as some people do, then this might not be true either. I couldn’t determine that as easily.

[ch4s3]

I’ve read the exact opposite of this claim in tons of papers. What are you looking at?

[dgfl]

For example this one:

https://doi.org/10.1093/ije/dyp166

It’s a decently big meta-review. It cites studies which more or less say exactly what I said very early, e.g. https://doi.org/10.1007/BF02071515

I might be completely wrong, of course. I’d rather be proven wrong than stay ignorant, so please do share the studies you had in mind.

[coldtea]

Probably ones not sponsored by the Big Sunscreen

[tomtomistaken]

This, and we are staying inside most of the time, so when spring arrives, we won't have gradual exposure but exposure all at once on the first sunny weekend we decide to get some sun.

[VBprogrammer]

Funny story. I started doing the couch to 5k running plan a few years back in January. Come March I realised I'd actually managed to get a tan (living in the outskirts of London, UK being further north than practically all of the inhabited North Americas).

Just being outside in whatever the weather consistently for 30 minutes or so every other day.

[ch4s3]

It’s just sunburns that cause skin cancer. It’s really that simple.

[seattle_spring]

That's .. just not true at all.

[ch4s3]

While the cause is UV exposure, sunburns drive most of the actual risk.[1] so it not technically true that skin cancer is only caused by sunburns, most melanomas come from sunburns. There’s a very linear dose response.

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC2873840/

[DANmode]

More accurately, “sunburn events”.

[shakna]

There's a hole in the atmosphere where I live. Incidentally, one of the highest skin cancer occurrences in the world.

Calling it overblown, is... A dangerous sentiment.

We tore a hole in our atmosphere. This is not the natural way of things, no. But we do have to live with the consequences.

[coldtea]

Unless you live in Antarctica, the above is simply not true...

[dmd]

You live in Antarctica?

[shakna]

Not literally above me, no.

But considering it affects everyone, its not something to ignore - especially in a region that is already 10% more UV intense than most of the world.

[coldtea]

Unless you live in Antarctica it doesn't "affect you" in the skin cancer from sun exposure way, just in the "general climate issue" way. And we're not discussing that here.

[dmd]

You do know that the 'ozone hole' got fixed, right? It's not back to baseline, but the Montreal Protocol is one of the major achievements of collaborative science and eco-politics of the late 20th century.

There is some global thinning, but it's minor. If you don't live literally at the south pole where the actual hole is, it's not a huge change compared to most other sources of skin cancer risk.

[shakna]

You do know its still healing right? Which is not past tense?

[tpoacher]

You do know that this is a Wendy's, right?

[hollerith]

I agree. When it is sunny, I get at least 20 min of sun on my bare skin and in my eyes (not protected from UV by glasses) every other day as recommended by neuroscientist Andrew Huberman. I am however careful not to get a lot more than that at once and have high-UPF clothing, hat and sunglasses to protect myself if I ever do need to be out in the sun for an extended period. (I am of Northern European ancestry.)

Even though I believe that the vitamin D we can buy in bottles is probably just as good as the vitamin D my skin makes, I do not consider vitamin D supplementation an adequate replacement for getting UV light on my skin and in my eyes because vitamin D production is only one of the benefits of getting UV light on the skin and in the eyes. (BTW I think HN put way too much emphasis on vitamin D.)

There are UV light receptors (that use a compound called neuropsin to sense the UV light) on the skin and in the parts of the brain that receive UV light (which gets into the skull mainly through the eyes). These receptors have nothing to do with vitamin D. Getting UV light onto these receptors is a more potent trigger for the release of endorphins in the brain than exercise is.

Regular UV light exposure also increases levels of sex hormones in men and in women. In men, increasing testosterone increases optimism and motivation and drive. Again, IIUC this effect has nothing to do with vitamin D.

When people eat plants, the compounds (e.g., lutein, zeaxanthin and lycopene) that plants use to protect themselves from UV light and blue light tend to be absorbed and to end up in high concentrations in the retina. If you do what I do, namely, get UV light from the sun every other day in moderate doses, then I suggest making sure you are getting plenty of these compounds. (Alexis Cowan says that omega 3 is helpful here, too.)

[seattle_spring]

> I get at least 20 min of sun on my bare skin and in my eyes (not protected from UV by glasses) every other day as recommended by neuroscientist Andrew Huberman

Andrew Huberman peddles nothing more than pop-science supplement grift. I highly recommend you get your health info from somewhere other than bro-optimization podcasts and "light therapy" hucksters.

[m463]

I have known quite a few people personally who have found (and removed) skin cancer.

I don't know if that means anything, it isn't n=1 sample size, it is more and my gut says it might be statistically significant.

[estearum]

> I think we’re starting to find that the “if you get sunlight you will develop skin cancer” mantra is way overblown, if not outright wrong.

Citation needed