This study examined the relationship of sleep characteristics to psychiatric diagnosis and mood in three hundred and seventy-five new referrals to a psychiatric clinic in London. Anger was associated with the greatest amount of sleep disturbance throughout the night. Sadness was associated with going to bed early with some delayed onset of sleep and early awakening; anxious mood with initial insomnia and delayed awakening; tension with going to bed late but sleeping well. The greatest amount of over-all sleep disturbance was found in neurotic depression when compared to endogenous depression and anxiety state. In neurotic depression, there was reduced sleep with both delayed sleep onset and early awakening. In contrast, there was no significant sleep reduction in endogenous depression which was associated with going to sleep early and waking early. Anxiety state was characterized by delayed sleep and late waking without a significant sleep reduction.