Medical Author: Melissa Stoppler, M.D.
Medical Editor: Barbara K. Hecht, Ph.D.
Daily therapy with a light box is a valid treatment that can provide relief for sufferers from seasonal affective disorder (SAD). The relief obtained by exposure to light is comparable to that achieved with antidepressant medications, according to a review of multiple studies.
Seasonal affective disorder (SAD) is a common form of depression. It affects an estimated 4-6% of the population, or about 1 in every 25 people. For reasons that are not known, women have SAD four times as often as men.
The symptoms usually begin in early adulthood and characteristically occur at a specific time of the year. These symptoms may include feelings of sadness and lethargy (sluggishness), changes in appetite and weight, and increased sleepiness. SAD sufferers may also encounter increased difficulties in interpersonal relationships.
The vast majority of people with SAD experience it during the winter months (starting in the late fall), but summertime depression is also a recognized form of SAD. SAD during the winter is believed to result from an inadequate amount of exposure to sunlight, although the exact mechanism by which low light levels result in depression is unknown.
Researchers at the University of North Carolina did what is called a metanalysis. They reviewed and analyzed all previously published studies on the efficacy of light-box therapy.
In light-box therapy, a person spends a specific amount of time each day (ranging, for example, from 10 minutes at the beginning of treatment to 90 minutes later in therapy) seated in front of a high-intensity light-emitting source. Most people receive light therapy in the winter months and continue until spring arrives.
Over 100 research studies on light therapy were reviewed, but only those meeting strict study design criteria were selected for the metanalysis. The 20 studies selected showed that light therapy was fully as effective as antidepressant medications in relieving the symptoms of SAD and was also beneficial in relieving non-seasonal depression.
Light therapy is not without risks. Potential side effects of this treatment include increased sensitivity to light (photophobia), insomnia, or sleep disturbances (if the therapy is administered late in the day). Patients may also report headache, fatigue, and irritability. Some experts caution that damage to the retina could occur with light therapy but this has not been documented.
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In addition to light therapy, SAD may also be treated with antidepressant medications, individual or group psychotherapy, or a combination of methods. Talk to your doctor if you experience seasonal depressive symptoms. He or she can help you decide upon the treatment that's best for you.
Reference: Golden RN, Gaynes BN, Ekstrom RD, Hamer RM, Jacobsen FM, Suppes T, Wisner KL, Nemeroff CB. The efficacy of light therapy in the treatment of mood disorders: a review and metanalysis of the evidence. Am J Psychiatry. 2005 Apr;162(4):656-62.
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