Sleep disorders and depression with atypical features: response to valproate.

Symptoms of so-called atypical depression, such as hypersomnia and lethargy, may accompany specific sleep disorders. It is often difficult to determine which disorder is "primary". The authors examine three cases of depression with atypical features associated with specific sleep disorders and report a favorable response to valproate. Some clinical features of the cases suggest a primary sleep disorder with secondary affective symptoms. However, valproate may have direct mood-altering effects as well as effects on sleep physiology. The implications of these findings for diagnosis and treatment are discussed.