[Seasonal affective disorder and light therapy].

Seasonal affective disorders (SAD) represents a subgroup of major depression with a regular occurrence of symptoms in autumn and winter and full remission in spring and summer. Light therapy or phototherapy has become the standard treatment of this type of depression. The phototherapy is affective therapy for depressive symptoms of SAD. However, the action mechanism of light therapy is uncertain. Finally, new lines of the investigation of light therapy are aforementioned.