Seasonal affective disorders.

Seasonal affective disorder is a pattern of major depressive episodes that occur and remit with changes in seasons. It may be seen in major depressive or bipolar disorders, as described in the Diagnostic and Statistical. Manual of Mental Disorders (DSM-IV). The most recognized form of seasonal affective disorder, "winter depression," is characterized by recurrent episodes of depression, hypersomnia, augmented appetite with carbohydrate craving, and weight gain that begin in the autumn and continue through the winter months. Physicians have many options for treating seasonal affective disorder. While questions regarding the validity of seasonal affective disorder as a syndrome and the mechanism of action of light therapy continue to be investigated, the established effectiveness of light therapy in patients with winter depression supports the usefulness of assessment for this seasonal pattern and consideration of light therapy as an option in addition to existing treatment choices.