The purpose of the study was to determine whether polysomnographic rapid eye movement (REM) sleep parameters distinguish between psychotic patients with and without a history of suicidal behavior. We examined both hand-scored and automated measures of rapid eye movement (REM) sleep in psychotic patients with and without a history of suicidal ideation or attempts. Patients with suicidal behavior had significantly increased REM activity and time both in the whole night data and in the first REM period. These findings suggest an association between REM sleep abnormalities and suicidal behavior, perhaps related to alteration in serotonergic function.