If nature tends to catch your eye, you may have noticed that the number of leafless tress seems to be growing by the day. Where once stood a glorious Eastern Maple, you find but a lifeless skeleton -- winter's stern rebuke of summer's excess.
But in some cases, winter's influence extends even further.For people with seasonal affective disorder, the outward transformation visible on tree branches mirrors an internal transformation in which pleasure and happiness give way to depression during the winter months. To them, winter is as much a change of mindset as a change of seasons.
"I feel drowsy during the day and I notice that I tend to eat more in the winter," said Matt Egyhazy, a fourth-year Engineering student who suffers from a mild case of the condition.
Seasonal affective disorder, or SAD as it is usually called, is thought to be brought on by the shorter days of fall and winter.Sufferers report feelings of anxiety or despair, and may have trouble with sleep or sudden weight gain.
"It can be pretty severe. In some cases, people get so depressed that they can't go to work or engage in normal social activities," said Sandra Sigmon, professor of psychology at the University of Maine and a leading SAD researcher.
Although estimates vary, approximately 2 percent of Americans suffer from SAD, with women accounting for the vast majority of reported cases. The link between SAD and women is still being investigated.
"We haven't been able to come up with a valid biological hypothesis why women are four times more likely to suffer from SAD than men," Sigmon said. "We've been looking into psychological factors. It could be the case that women tend to focus on their feelings more so than men, and this might exacerbate the symptoms."
Curiously, the incidence of SAD does not increase all the way to the poles, but rather levels off in regions with permanent snow cover.It also is rarely observed below 30 degrees latitude, where sunlight is plentiful year round.
"In spite of the fact that Charlottesville is only in the mid-Atlantic, we do see a number of cases here," said Zack Cameron, a psychiatrist at the University.
The link between reduced daylight hours and the onset of SAD is still unresolved, but most scientists suspect that the hormone melatonin plays a key role.In the absence of light, melatonin is produced in greater quantities by the brain's penial gland.Higher levels of melatonin have been shown to cause symptoms of depression.
Another possible cause for SAD is not biological at all, according to Sigmon.
"We're looking at the role of activity level in SAD. People tend to curtail their activity level during the winter which in turn may increase feelings of moodiness and depression," he said.
The traditional method of treatment for SAD consists of direct exposure to intense light 30 minutes to an hour each day. Anti-depressant medications such as Prozac and Zoloft only are effective about 20 percent of the time.
"There's good evidence that light therapy works. It's not universally successful, but if you are fairly certain of your SAD diagnosis, light therapy is probably what you'll try first," Cameron said.
Although light therapy may be a clinician's first recommendation, Sigmon currently is investigating whether psychological techniques can be applied in the treatment of SAD. If she is successful, patients not only will experience relief from SAD symptoms, but also will be equipped with life skills that light therapy does not provide.