Tanning is a drug.
Well...sort of. According to recent research, people who tan themselves more than twice each week may be addicted to endorphins created in skin cells exposed to sunlight. Endorphins are opioid compounds that provide a mental boost and a feeling of wellbeing. Heroin and morphine are opioids, and just like these drugs, tanning can be addicting.
This theory was put to a test in a recent trial conducted by researchers at Wake Forest University Baptist Medical Center. Sixteen subjects were recruited: eight infrequent tanners, and eight frequent tanners. "Frequent" was defined as eight to fifteen tanning sessions per month.
Each subject was given 5 mg of naltrexone; a drug that blocks the effects of opioids by competing for opioid receptors in the brain. Naltrexone is used to treat opioid dependence and alcoholism.
Researchers steadily upped the naltrexone dosage until all subjects were receiving 15 mg. At that point, four of the frequent tanners displayed typical withdrawal symptoms such as jitteriness and nausea. Two of the four had to drop out of the study. Presumably they stripped to their skivvies and made a beeline for the beach.
None of the infrequent tanners had withdrawal symptoms.
On the upside, it's a good bet that all of these subjects have impressive vitamin D levels. The downside, of course, is a sharply increased risk of skin cancer. Richard Wagner, Jr., M.D. (who was not involved in the Wake Forest research), told WebMD Medical News that frequent tanning is a type of substance abuse so powerful that some skin cancer patients can't stop tanning, even though they're aware of the damage they're doing to themselves.
Most tanners, however, are probably not aware that they may be skin cancer patients in the making. As part of his research, Dr. Wagner took a trip to a beach where he used addiction questionnaires to survey a number of tanners at random. He told WebMD that about half the respondents had tanning habits that qualified as a substance-related disorder.