外刊阅读20240715｜你真的每天都需要防晒霜吗？

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When we step outside on a clear day, the sun’s ultraviolet light triggers the body to produce endorphins that lower stress and boost mood. UV rays also tell our skin to make vitamin D. And when we look up at the morning sun, our bodies recognize daytime and adjust our sleep-wake cycle accordingly. That might be enough to tempt some people to skip the sunscreen — indeed, dermatologists say their patients often worry they’ll miss out on these benefits.

Recent surveys reflect this fear: In one poll of more than 1,000 adults in the United States, 11 percent of respondents said they thought wearing sunscreen was more harmful than direct sun exposure. In another, 15 percent said they thought sun exposure was the only way to get vitamin D. But sunscreen also is our best weapon against skin cancer, which can be deadly. The sun’s UV rays damage the DNA in your skin cells , and that damage can add up over time. Every time DNA repairs itself, there’s a chance it develops a mutation that turns into cancer.

We asked nine experts whether you actually need to use sunscreen daily, and whether the sunlight’s potential benefits ever outweigh its risks. All said that there is no safe amount of unprotected sun exposure, and said you should be wearing broad- spectrum sunscreen with an SPF of 30 or more — every single day. Here’s what they want you to know about sunlight, sunscreen and your health.

Does sunscreen block the sun’s mood-boosting benefits? Not necessarily, said Dr. Elisabeth Richard, an associate professor of dermatology at the Johns Hopkins University School of Medicine. Even with daily sunscreen, you can still enjoy a mood boost from the sun’s visible light, or the light we can see with our own eyes. Visible light doesn’t cause DNA damage like UV rays do, but it can increase serotonin , a chemical in the brain that helps regulate mood. This is why using a light box can ease symptoms of seasonal affective disorder, said Dr. Deborah Sarnoff, a professor of dermatology at New York University.