Michelle, 40, and Aliyah, 16, both wearing sunscreen; Myrtle Beach, South Carolina. Photo by Jacq Harriet

What If Avoiding the Sun Is Bad for You?

The pros and cons of sun exposure don’t start and end with vitamin D and skin cancer

Markham Heid
Published in
13 min readJul 25, 2019

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ItIt was around 15 years ago that Dr. Matt Zirwas, an Ohio-based dermatologist, first noticed something curious about the people he was treating at his clinic.

“The older patients I was seeing [who had] lots of sun damage and lots of skin cancer would be very robust, very energetic people,” he says. These were people who, apart from their skin cancers, tended to be in excellent health and taking very few prescription drugs.

“But then I’d see these people who had beautiful skin and no cancers, and they were very low-energy and taking medications for all these different health problems,” he recalls. He began to wonder whether exposure to ultraviolet (UV) light, mostly from the sun, had more health benefits than he and other experts realized.

When most people consider UV light and its effects, skin cancer and premature aging come to mind. And there’s no question that exposure to the sun, tanning beds, and other sources of UV light damages the skin in ways that promote aging and cancer. That’s why most dermatologists and public health officials recommend that Americans slather sunscreen on exposed skin whenever they leave the house — even in the wintertime — or take other steps to avoid sun exposure.

“The standard line from dermatologists is that no part of your skin should ever be exposed to unprotected sun,” Zirwas says. “And I agree that if you’re talking about preventing skin cancer and aging, you want to avoid the sun.” But his clinical observations made him wonder whether the story on UV light was really all negative, and if a zero-tolerance policy on sun exposure was warranted when taking a broad view of human health.

“We evolved as outdoor creatures who were exposed to the sun, so it never made sense to me that sun exposure would be all bad,” he says.

Zirwas started reading the published literature on UV exposure and human health. In 2014, a study appeared that Zirwas says changed his thinking from “this is all kind of interesting” to “holy shit!”

That study was published in the Journal of Internal Medicine, and it examined 20 years of…

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Markham Heid
Elemental

I’m a frequent contributor at TIME, the New York Times, and other media orgs. I write mostly about health and science. I like long walks and the Grateful Dead.