Seasonal Affective Disorder (SAD) describes episodes of major depression that regularly occur during particular seasons. The most prevalent form of SAD is winter depression, marked by recurrent episodes of depression that begin in the fall or winter and, if left untreated, generally remit in the following spring or summer. The lifetime prevalence of SAD in the general population is approximately 0.5 to 3 percent.
Light therapy is well-recognized to be effective for mild-to-moderate seasonal depression. The standard and best studied devices for administering bright light therapy are 10,000 lux light boxes that use fluorescent bulbs emitting white light. Typically, the light source needs to be positioned approximately 16 to 31 inches from the patient’s eyes. The patient need not look directly at the light, which should be aimed downward to avoid glare. Patients are instructed to use the light box first thing in the morning after awakening at the same time every day for 30-60 minutes.
Recently, a study examined the effectiveness of light box therapy plus antidepressant medication for non-SAD depression and found that light therapy plus antidepressant medication was more effective than antidepressant medication alone. For this reason, in patients who suffer from depression of any cause, I always recommend a light box as safe and potentially helpful therapy.