People who suffer from winter depression known as "seasonal affective disorder" or SAD — or the less severe but more common "winter blues" — shouldn't seek relief in a tanning bed or booth, a leading expert on light therapy warns.
SAD is often treated with daily sessions of exposure to bright light. While some isolated reports have linked tanning to improvements in mood, Dr. Michael Terman told Reuters Health, the fact is that real light therapy works through the eyes, not the skin, and uses a completely different type of light.
Even if artificial tanning did turn out to improve mood, the increased risk of skin cancer would far outweigh its benefits, added Terman, who is the director of the Center for Light Treatment and Biological Rhythms at New York-Presbyterian Hospital in Manhattan.
According to The Skin Cancer Foundation, the newest sunlamps produce up to as a dozen times as much ultraviolet light as real sunshine, while tanning bed users are at greater risk of developing skin cancers. UV light can also harm the eyes, Terman noted, and studies have shown the goggles people use in tanning beds and booths can allow significant amounts of the damaging rays to reach the eyes.
Resetting biological clocks
Some people become clinically depressed in the fall and winter months, while many more — an estimated one-quarter of people living in the middle and northern latitudes of the U.S. — will see a drop in mood as the days get shorter. We rely on bright morning light to reset our biological clocks every day, and when work and school obligations force us to wake up well before sunrise, our biological clocks start running out of sync with our external environment. "That is a formula for depression," Terman explained.
So light therapy is believed to work by resetting our biological clocks with a properly timed dose of artificial sunshine. It's effective both for SAD and for less severe seasonal mood problems. However, ultraviolet light that tanning beds and booths use to brown the skin is not part of the prescription.
Neither is light on the blue end of the spectrum, Terman added. Some companies have latched on to studies suggesting extra benefits to blue light by making blue-light-only light boxes, despite the lack of any evidence for their clinical benefit. In fact, he noted, this type of light is so harsh that it's difficult for people to look at.
The Food and Drug Administration doesn't regulate light boxes, so there's no guarantee that devices on the market will help, he said, and some evidence that they could be harmful, for example by failing to adequately filter out ultraviolet radiation.
Effective light boxes use soft white lights tending toward the red end of the spectrum, and should emit 10,000 lux of illumination to be optimally effective, according to Terman. Light boxes should also have a filter or diffuser to protect the eyes and skin from ultraviolet light, he added. Staring at a naked bulb can harm the eyes, and won't be effective, because light actually exerts its beneficial effects at the periphery of our vision.
Terman supervises a non-profit Web site, the Center for Environmental Therapeutics (www.cet.org), that offers information on how to choose a light box, as well as a self-test that lets people figure out if they might need to see a doctor for seasonal mood problems. "There's a tendency to want to self-treat with light therapy," Terman said. "Self-treatment with light therapy is clearly contraindicated for anyone with major depression. There are too many ways you can do it wrong, and you'll be even worse for it."