Light therapy can help overcome seasonal affective disorder

Seasonal affective disorder strikes many people during the dark winter months. Light therapy can help ease the depressive symptoms of SAD.
BY Anthony L. Komaroff, M.D. For The Oklahoman Published: February 11, 2014

DEAR DOCTOR K: I have seasonal affective disorder so I dread the approach of winter. What can I do?

DEAR READER: Here in Boston, it can get dark before 4:30 in the afternoon. For some people, the shorter days of this time of year bring on seasonal affective disorder (SAD), also known as winter depression. People with SAD tend to develop symptoms every year. They start gradually in late autumn and build up during the winter months. For many, relief may not come until the longer days of spring.

Like other forms of depression, SAD produces sadness, lethargy and fatigue, loss of interest in people and activities, impaired concentration and irritability. SAD also leads to oversleeping and overeating. (Most other forms of depression produce insomnia and weight loss.)

Only one drug, bupropion (Wellbutrin), is approved for SAD. But selective serotonin reuptake inhibitors (SSRIs) and other antidepressants are also effective.

Another treatment, known as light therapy, is at least as effective for treating SAD as antidepressants. Light therapy involves sitting close to a fluorescent light box for 30 minutes each day. The light is much more intense than the light produced by an ordinary light bulb. Proper light boxes provide 10,000 lux. (The “lux” is a measure of light intensity. By way of comparison, indoor light is about 100 lux. A bright sunny day is 50,000 lux or more.)

Bright white light acts on cells in the eye's retina. The retina connects to a part of the brain that helps control circadian rhythms of sleep and wakefulness. Scientists believe these rhythms may become disrupted in SAD.

Light treatment is relatively safe and side effects are uncommon. Some people become irritable, develop headaches, or their eyes are bothered by the brightness of the light box. Reducing the time of each light box session, or sitting somewhat farther away from the box, can often correct that problem.