Second Wave of Damage After Sun Exposure

Health Writer

You've been out in the sun...too long. You head indoors, thinking that once you get out of the sun, you can block any further damage to your skin. But researchers have recently discovered that the effect of the sun on the skin continues, for hours.

The study, completed at Yale School of Medicine and published in Science Magazine found that DNA damage, caused by sunlight, continues to occur in cells containing melanin, even after the skin is no longer exposed to the UV rays.

Melanin is what gives skin its color. Darker skinned people have more melanin than those who are fair skinned. It has been thought the melanin helps protect skin from skin cancer. But the recent study showed that the process of DNA damage continued in cells containing melanin. In other words, there were two "waves" of damage. The first occurred when the skin was exposed to UV rays - in this stage melanin helped protect the skin. The second wave occurred later, when the skin was no longer exposed to UV rays - and involved cells containing melanin. This second wave could last for up to three hours after sun exposure.

This information puts sun exposure in a whole new light. While scientists previously believed that stepping out of the sun, into the shade or going indoors, would prevent further sun damage, this study shows that isn't true. Instead, they found that half of the sun damage occurs after sun exposure. The take-away is the same, however. Stay out of the sun or limit your exposure between the hours of 10:00 am and 2:00 pm. Wear protective clothing, such as wide-brimmed hats when outdoors.

The good news is the scientists believe there may be a way to limit the further DNA damage. During their study, they used two different chemicals to try to stop the continued damage and found that Vitamin E might be helpful. They believe that this information could be used to create an "after sun sunscreen." There would be one sunscreen to help protect you when outdoors and a second cream to apply when coming inside that would help prevent the second wave of DNA damage in your skin.

For more information:

How to Choose the Best Sunscreen For You

Does Sunscreen Really Protect You From Skin Cancer?

Homemade vs. Store Bought Sunscreen

Sunscreen Questions? A Dermatologist Provides Answers