Why do suntans develop hours after we get home from the beach? A new study explains.
If you’ve ever left the beach without a suntan only to find it showing up hours later, you may wonder why. Now a new study from Tel Aviv University has a possible answer.
The study, which was published in the Journal of Investigative Dermatology, says that how people tan has to do with the way the body attempts to protect itself from exposure to ultraviolet (UV) radiation, which most commonly comes from the sun or tanning beds, according to the Centers for Disease Control and Prevention (CDC).
It’s this UV radiation that causes skin to tan for some people in the first place. While many people may desire the tanned look, it’s actually a sign that the skin is damaged and attempting to repair itself.
“We have two mechanisms designed to protect the skin from exposure to dangerous UV radiation,” said Nadav Elkoshi, one of the authors of the study, in a news release. "The first mechanism repairs the DNA in the skin cells damaged by the radiation, while the second mechanism involves increased production of melanin, which darkens the skin in order to protect it from future exposure to radiation."
Elkoshi explained that the reason the tanning phenomenon does not occur immediately when the body is exposed to the sun is that the “mechanism that repairs our DNA takes precedence over all other systems in the cell, temporarily inhibiting the pigmentation mechanism.”
“Only after the cells repair the genetic information to the best of their ability do they begin to produce the increased melanin,” she said.
What experts want you to know
There’s a misconception that tanning is a safer way for your body to respond to sun exposure, as opposed to a sunburn. However, Dr. David J. Goldberg, dermatologist at Schweiger Dermatology Group in New York City, says that this study makes it clear that “tanning is not a healthy response — it only occurs after the DNA does damage to our skin cells.”
Goldberg says the study proves what we have assumed about sun exposure for decades. "DNA damage to the skin occurs from ultraviolet exposure," he says. "This DNA damage is what leads to both skin cancer and wrinkles."
He adds: "Think of it as akin to the DNA damage to our body cells from a variety of toxins that leads to cancer in the body. In regard to ultraviolet exposure, our natural attempt to healing from the ultraviolet-induced DNA skin damage is the first task — only to be followed by a ‘tan.’”
Dr. Shari Lipner, associate professor of clinical dermatology at the Weill Cornell Medical Center, tells Yahoo Life that “this study reinforces previous data showing that UV exposure causes DNA damage and that tanning is a protective mechanism.”
Why it matters
The study illustrates that it's important to think of a tan, and not just sunburn, as evidence of DNA damage.
This DNA damage “makes us more prone to forming nonmelanoma and melanoma skin cancers,” says Lipner. In general, “sun exposure and tanning increase risk of skin aging and skin cancer,” she says.
Experts agree that using sunscreen before going outside, and reapplying it every two hours, is a good way to protect skin from sun damage. In addition to sunscreen, you can also wear protective clothing such as long sleeves, a rash guard or other clothing that have UV protection built in.
In addition, Lipner notes that it’s important to “perform self skin checks monthly and see a board-certified dermatologist for any new or changing spots on the skin.” This way, if there is any damage from the sun, such as skin cancer, it can be addressed by a doctor right away.
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