On those gray, chilly winter days—when daylight fades early—you may have a temporary bout of the blues. But some 5 percent of people in the U.S. experience something more serious: a form of depression called seasonal affective disorder, or SAD, which develops in autumn and winter and can last for several months.

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SAD, which is most common in northern climates, can be just as debilitating as clinical depression, says Kathryn Roecklein, Ph.D., associate professor of clinical psychology at the University of Pittsburgh. The risks of complications, including suicide, are the same with both disorders, she notes.

Some symptoms of SAD are similar to those associated with other types of depression: sadness, fatigue, excessive sleepiness, withdrawing socially, and trouble concentrating. But SAD sufferers also tend to move slowly, crave carbohydrates, and gain weight.

If you think you might have seasonal affective disorder, let your doctor know, so he or she can evaluate you for the condition. Here’s what can help.

Turn Up the Lights

If you have some seasonal symptoms of depression but they’re relatively mild, relief might be as simple as a good long walk each morning, says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser.

But beyond that, several studies conducted over the years suggest that regular exposure to light might be one of the most effective treatments, Roecklein says.

Bright light therapy involves sitting in front of a lamp known as a light box for about 30 minutes a day during the darkest months of the year. It has been found to help about 50 percent of people with seasonal affective disorder, which is linked to the declining hours of sunlight that come with winter.

The light boxes produce up to 10,000 lux of light (similar to the light intensity just after sunrise or just before sunset). You can buy them online and in many drugstores, but you should consult a doctor first, Roecklein says.

“The last thing I want someone to do is buy a light box off of Amazon, try it for two days, decide it doesn’t work, and put it in the closet,” she says.

And light therapy can occasionally have side effects, including headache, eye strain, and agitation.

Therapy, Medication, and More

For those who reap no benefits from a light box, research suggests that cognitive be­havior therapy, which is meant to help people recognize and change negative thought and behavior patterns, also eases SAD symptoms.

It might even prevent symptoms from recurring the following year. “The theory is that people learn different ways of thinking and behaving” that can help them cope with future depression, Roecklein says.  

If none of those approaches help, talk to your doctor about whether medication might be appropriate. The antidepressant bupropion (Wellbutrin and generic) is approved by the Food and Drug Administration for seasonal affective disorder. To learn more about bupropion and other antidepressants, see our CR Best Buy Drugs report.

Also, try getting active: Several studies show that doing 60 minutes of outdoor exercise in the morning can be a big boost for people with SAD.