Diligently applying broad-spectrum sunscreen is one of the best defenses against skin cancer. But according to a new study published in Science, we might need a separate sunscreen for the evening hours—a type of sunscreen that would protect us from the additional DNA damage that continues to happen even after we’ve retreated from the sun.
Led by Yale University researchers, the study reports that UV light exposure from the sun, as well as tanning beds, can cause DNA damage in skin cells for more than three hours after exposure. By exposing human and mouse melanocytes (cells that produce skin pigment) to UV lamp radiation, the scientists discovered that the UV rays triggered DNA mutations in the melanocytes immediately and long after the cells were removed from light.
Since your regular sunscreen is meant to help prevent UV damage in the first place, applying it after you’ve already been unprotected won’t help block this in-the-dark damage. Rather, scientists are exploring an “evening-after sunscreen” that can thwart the DNA changes that occur in the melanocyte cells.
While the specific ingredients for an evening-after sunscreen have yet to be determined, the researchers did begin looking into the antioxidant vitamin E for its potential to prevent and even reverse these destructive effects on skin’s DNA. However, research on vitamin E’s ability to effectively block the lingering outcomes of UV exposure is still far from conclusive. “Even if vitamin E were effective in the lab, it is not clear that including it in a sunscreen would get it into the skin,” says one of the study authors, Douglas E. Brash, PhD, clinical professor of therapeutic radiology and dermatology at Yale School of Medicine.
“I’m told that vitamin E is in sunscreens to protect the sunscreen [from degrading] as it sits on top of the skin,” Brash adds. Instead of boosting the efficacy of existing sunscreens like vitamin E, an evening-after sunscreen aims to divert energy away from the melanin fragments that trigger the DNA damage, says Brash, who’s currently in talks with cosmetics companies (along with the other study authors) to further research and formulate a product.
In the meantime, shielding yourself from UV rays during the day is the single best way to help protect against these post-exposure problems. Despite the push for daily sunscreen use, most adult Americans are still not consistently wearing it. In May 2015, researchers from the Centers for Disease Control and Prevention (CDC) revealed in the Journal of the American Academy of Dermatology that only 14.3 percent of men and 29.9 percent of women surveyed reported that they use sunscreen on a regular basis. An SPF 30 sunscreen with broad-spectrum protection is the minimum, according to Janet Lin, MD, a dermatologist at Mercy Medical Center in Baltimore. Seeking shade, wearing UV-protective clothing, sunglasses and hats will also help, she says.
Although an evening-after sunscreen is not yet available, this new Yale study reinforces the fact that sun damage, and consequent skin cancer, is all about lack of protection. So grab your favorite hat and sunscreen—stat.