Down in the Dark

When the days get shorter and the wind blows colder, it's easy to feel a little glum. But for some people the darker days can trigger serious depression. As many as half a million Americans are struck each year by seasonal affective disorder, or SAD, a type of depression that comes and goes with the darkest half of the year; another 10 percent to 20 percent of the population experience something just short of it. And though it's not clear why, doctors say women are three times as likely as men to be affected by it.

This isn't the holiday blues. As Dr. Norman Rosenthal, the psychiatrist who wrote the defining medical journal article on the disorder in 1984, explains, the blues are gone in a week or two, but SAD typically starts around Columbus Day and hangs on until about Easter.

Still, the confusion between the two may help explain why, more than 20 years after SAD was first diagnosed, most people with the disorder aren't getting help. Rosenthal said a recent study found that even among subjects who reported having experienced an average of 13 cycles of SAD symptoms, 60 percent had never gotten a diagnosis or treatment. "A lot of these cases still don't get recognized, even though SAD can be very persistent, and some people become disabled by it," Rosenthal said.

Even though it's called SAD, the typical symptoms extend beyond unhappy feelings. As Rosenthal describes it in his book "Winter Blues," SAD not only causes symptoms of depression (feelings of irritability, difficulty concentrating, fatigue, oversleeping, social isolation) but, often, a strong craving for sweet and starchy foods, and the weight gain that inevitably accompanies it. Like people with other forms of serious depression, those with SAD can find it hard to hold down a job or function normally, and some may contemplate suicide.

Rosenthal, now a clinical professor of psychiatry at Georgetown University Medical School, said he experienced some of these symptoms himself when he first moved to the United States from South Africa in the late 1970s, to begin work as a researcher at the National Institute of Mental Health. During his first autumn in Washington, D.C., he couldn't help noticing that as the days got shorter his energy level declined. "I didn't know what hit me," he says now. "I dragged myself through that first winter." Equally surprising, he said, was the change he noticed in the spring. "As the snow melted," he said. "my energy came back."

At the time, groundbreaking work was being done at NIH on light's effect on the brain, and coincidentally Rosenthal met a male patient who complained of severe mood changes that lasted from late fall to spring. That's when Rosenthal had his "Ah-ha!" moment. "I wondered if there were other people like him, and wouldn't it be great to study them," Rosenthal said. He's been doing that ever since.