LIGHT TREATMENT FOR SEASONAL AFFECTIVE-DISORDER - THEORETICAL CONSIDERATIONS AND CLINICAL IMPLICATIONS

The concept of seasonal affective disorder (SAD) includes any depressi on whose onset is related to a certain season. Reduced environmental l ight is hypothesized to be the main precipitating factor of winter dep ression. Light treatment is used to prevent the onset of depressive ep isodes and to reduce depressive symptoms in patients with depression d uring winter months. The mechanisms of action which lead to the well-d ocumented antidepressant response are still unknown. Several hypothese s of the pathogenesis of SAD are discussed, and the clinical practice of light treatment is reviewed.