Light Therapy and Prozac—Both Effective for Seasonal Depression

Healthnotes Newswire (August 24, 2006)—People with seasonal depression who choose light therapy can get as much relief as people who choose a commonly prescribed antidepressant, a new study finds.

Seasonal affective disorder (SAD) is characterized by cyclical depression that comes on in the fall or winter and resolves in the spring or summer. Diminishing sunlight triggers the darkening mood in people with SAD.

In addition to low mood, people with SAD experience some of the other symptoms of depression: low energy, oversleeping, overeating (especially sweets), and weight gain. They might also have trouble functioning at work and in their relationships. People in northern climates are more susceptible to SAD, and studies have found that as many as 2.7% of Canadians and Americans have SAD.

A number of trials have found light therapy to be an effective treatment. Light therapy is usually performed by sitting close to a “light box” (a device designed to emit bright light) for 30 to 60 minutes per day. A few preliminary comparison studies have found that light therapy works as well as or better than antidepressants.

A comparison trial, published in the American Journal of Psychiatry, studied 99 people with SAD who were randomly assigned to one of two groups: one group used a light box delivering 10,000 lux for 30 minutes and took a nontreatment pill (placebo) every morning for eight weeks in the winter; the other group used a neutral light box (100 lux) believed to have no therapeutic value and took 20 mg of a commonly prescribed antidepressant (fluoxetine, the generic version of Prozac) every morning.

After the first week, people using light therapy showed more improvement than those using medication. By the second week, however, this difference had disappeared, and there was no difference between the groups at the end of the study. The symptoms of depression were reduced by 50% or more in 67% of the people in both groups, and depression resolved in 50 to 54% of the people.

Antidepressant medications can cause some unwanted side effects such as sleep disturbance, anxiety, heart palpitations, and sexual dysfunction. Based on the evidence from this and previous research, light therapy is a reasonable option for people who don’t want to use antidepressants or who experience intolerable side effects.

“The choice of treatment always depends on individual assessment of risks and benefits,” the authors stated in their conclusion, “but in the absence of clear superiority for either treatment, patient preference should be a major factor in treatment selection.”

Meg White, MA/LMHC, a psychotherapist in Seattle who works with many people who suffer from SAD, has another perspective on using light to combat depression in the winter. “I have recommended 30 minutes in the morning with a light box and have seen it work. It gives people some time to meditate which adds to its benefit. But, I really like to emphasize going outside to get light. I think the issue of depression in winter is intricately tied to immobility as well as light deprivation. A lot of people don’t spend time outside in the winter because it’s cold. Everyone feels better in the winter if they exercise outside during the sunlit hours, including and maybe especially people with SAD.”

(Am J Psychiatry 2006;163:805–12)

Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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