Light therapy for winter depression.

6 | Harvard Women’s Health Watch | February 2005 www.health.harvard.edu M ost of us welcome the sun’s effect on our mood, especially after a stretch of gray days. But for some people, reduced daylight during fall and winter months can bring on full-blown depression. For them, bright sunlight may represent more than a nice change in the weather: It can have therapeutic benefits. Exposure to the right kind of light, whether indoors or out, is now the first-line therapy for alleviating the symptoms of seasonal affective disorder (SAD). SAD is a form of depression that follows a seasonal pattern, almost always worsening during the darker winter months and returning every year at roughly the same time. It’s also known as “winter depression” or “winter blues.” Though there’s some evidence of a spring-summer pattern of depression, SAD is most commonly a fall-winter disorder. This condition accounts for about 10% of all cases of major depression and occurs mostly in women. SAD makes you feel unhappy, anxious, tired, and irritable. It leaves you disinclined to socialize, and it undermines your ability to concentrate — all symptoms typical of depression. Many women increase their calorie intake (especially from carbohydrates) and sleep longer than at other times of the year. Interestingly, people with winter depression are often happy and productive the rest of the year. SAD usually begins in a woman’s late teens or early 20s and often disappears after menopause. No one knows what causes winter blues, but there’s some evidence implicating melatonin, a hormone produced in the brain.