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."