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Posted on Sat, Mar 9, 2013 : 5 a.m.

Lighten up to combat seasonal affective disorder

By Ask Dr. K


It's that time of year when the gloom of late winter sends my mood plummeting. What can I do about seasonal affective disorder?


Summer is a time when many of us take vacations, and for younger people, it's time out of school. So lots of people feel a pang of regret when summer ends. I always do.

That's normal. But some actually develop depression with the season's change. This is known as seasonal affective disorder (SAD).

SAD seems to be triggered by more limited exposure to daylight. Typically, it comes on during the late fall or winter months and subsides in the spring. Symptoms are similar to general depression. They include lethargy, loss of interest in once-pleasurable activities, interpersonal problems with friends and family members, irritability, inability to concentrate, and a change in sleeping patterns, appetite or both.

The mainstay of SAD treatment is light therapy, also called phototherapy. This involves daily sessions of sitting close to a special light source that is far more intense than normal indoor light. The recommendation is typically to get 30 minutes of exposure to an intensity of 10,000 lux (a measure of light) each day. But not everyone needs that much exposure.

In this therapy, the light must enter through your eyes to be effective. Some people feel better after only one light treatment, but most people require at least a few days of treatment. Some people even need several weeks. You can buy light therapy boxes without a prescription, but I recommend working with a professional who can monitor your response.

Side effects are mild for many patients, but may be more of a concern for others. In people who are vulnerable, bright light may trigger a so-called manic episode of abnormally elevated mood. That's why mood-stabilizing medications are often recommended while undergoing light therapy. Likewise, since rashes can result, let your doctor know about any skin conditions that seem to be made worse by exposure to sun.

Does light therapy work any better for SAD than antidepressant pills? There are few studies of this question. For some of my patients, the choice of light therapy is based on a desire to avoid pills: Light therapy seems more natural.

In my experience, light therapy doesn't work for everyone with SAD. Clearly, some people are more likely to respond positively, but we don't yet have any way of knowing who they are. One exception to that statement: If a person has responded positively to light therapy in the past, he or she is likely to benefit again in the future.

If light therapy doesn't work for you, along with antidepressants you should consider a form of talk therapy called cognitive behavioral therapy. For some people, combining these treatments with light therapy works better than any one of them individually.

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)

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