Mood disorders and chronic insomnia share complex theoretical and clinical relationships. This article reviews the subjective symptoms and polysomnographic findings of subjects with mood and insomnia syndromes. The polysomnographic findings reviewed include macro-architectural and micro-architectural data. Various treatments of patients with insomnia and mood disorders will be presented, including both behavioral and pharmacological interventions. Depression and Anxiety 14:7–18, 2001. © 2001 Wiley-Liss, Inc.