Sun-worshipers out working on their tans might not just be after a bronzed look. They may be addicts.
A new study shows that ultraviolet radiation can not only trigger skin browning, but also spark the release of feel-good chemicals, known as endorphins.
Scientists have suspected for some time that exposure to UV radiation has the potential to become addictive. The New Jersey woman known as “Tan Mom” brought attention to the problem, popularly known as “tanorexia.”
Though the new findings are in mice, the researchers believe they may explain why some people can’t seem to kick the tanning habit despite all the public service announcements about cancer risks and premature skin aging. Since endorphins work their magic through the same pathway as heroin and other opiates, sunbathers and tanning salon fans may actually become “addicted” to UV.
The researchers are particularly concerned about the endorphin effect in young people.
“Tanning salons are for the most part regulated at the cosmetics level in many states,” said study coauthor Dr. David Fisher, chairman of the dermatology department at the Mass General Hospital and Harvard Medical School. “Teenagers can walk in and easily have tanning bed exposure. Many package deals are inexpensive in the beginning. Companies seem to have learned from experience that tanning has a propensity to be addictive. So it’s the perfect business model.”
For the new study, Fisher and his colleagues ran several experiments in mice. In the first, rodents with shaved backs were exposed to UV at a dose that is roughly equivalent to 20 to 30 minutes of “midday sun exposure in Florida during the summer for a fair-skinned person of average tanning,” Fisher says, adding that the exposure wasn’t enough to sunburn the mice.
After a week of mouse UV exposure, the researchers tested levels of beta-endorphin in the rodents’ blood. Sure enough, endorphin levels had risen sharply, so much so they were enough to blunt the rodents’ sensation of pain.
Though the researchers can’t say anything about how the endorphins make mice feel, they suspect the brain chemicals create a pleasant experience that both mice and humans will want to revisit.
“There are lots of data for opiate drugs that clearly show euphoria, well-being, etc., but I believe it is currently unknown whether beta-endorphin, the body’s ‘natural’ opioid, does the same things,” Fisher says. “It is a plausible speculation that it could, since it acts on the same molecular circuitry in our bodies and brains.”
Of course, the other side of addiction is withdrawal.
In a later experiment the researchers injected rodents that had been regularly exposed to UV with a drug that blocks opioids—the same drug that is given to people when they overdose on heroin.
Sure enough, the mice started showing signs of withdrawal, including shaking, shivering, and teeth chattering.
"The immediate gratification has a way of obscuring distant dangers."
Although the new study is in rodents, Dr. Charles Bradberry suspects its findings would be applicable to humans. “This is a very basic and fundamental neurochemical pathway,” says Bradberry, a professor of psychiatry and neuroscience at the University of Pittsburgh.
“The thing that is very impressive is it does suggest that if people stop being exposed to UV light, they may experience discomfort and will learn that by re-exposing themselves, they will relieve the discomfort. It fits very nicely with certain conceptualizations of addiction.”
And, Bradberry says, it may go a long way to explaining why people continue to spend time in tanning salons despite all the dire warnings of consequences.
“The immediate gratification has a way of obscuring distant dangers,” he says.