Winter Darkness, Season Depression
Winter depression is still a mystery to scientists who study it. But researchers agree that people who suffer from seasonal affective disorder are particularly sensitive to light, or the lack of it.
om Wehr, researcher at the National Institute of Mental Health, has proposed a new explanation for seasonal affective disorder: It may stem from too much melatonin. When the brain's pineal gland starts pumping out melatonin, we get sleepy. During winter, animals secrete melatonin for longer periods than they do at other times of the year. Wehr discovered that people do, too -- but only those who suffer from seasonal affective disorder.
Light therapy would still work if melatonin were the main culprit, because light controls melatonin levels. Researchers are also testing a drug called propranalol, which they hope will improve seasonal affective disorder symptoms by curtailing melatonin flow in the morning hours. Lewy is studying the effects of small melatonin doses given in the afternoon, hoping that they will adjust circadian rhythms.
Raymond Lam, MD, researcher at the University of British Columbia, Canada, and others are studying the role of brain chemicals like serotonin and dopamine. "We know there are interactions between the serotonin system and the circadian system," Lam says.
Some antidepressants like Paxil and Prozac work for some seasonal affective disorder sufferers. But Lewy says he prefers light therapy to antidepressants, which he says "are probably more of a Band-Aid," because they're not specific to winter depression.
Terman has been testing yet another new way to treat seasonal affective disorder. This therapy involves aiming a stream of negatively charged ions at a person sleeping on a special conductive bed sheet. The discovery that high-density negative ions (not the same ions produced by home air filters) helped people with seasonal affective disorder came accidentally from a previous study. A second study, which will end later this year, has also found a beneficial effect.
The air is full of negative ions in springtime, and not in the winter. But that doesn't explain how ion therapy works. "We don't yet have an answer to that question," Terman says; nevertheless, "We're now convinced that it's real."