Nocturnal sleep of 14 patients with HIV infection was characterized by longer sleep onset latency, shorter total sleep time, reduced sleep efficiency, more time spent awake and in Stage 1. There was significantly less sleep Stage 2 than in healthy controls. REM latency was slightly reduced and correlated negatively with depressive symptomatology, while percentages of REM and slow wave sleep were normal. Patients without complaints at the time of the investigation exhibited similar sleep abnormalities. The results stress the usefulness of polysomnography as a sensitive methodology for detection and monitoring of CNS affection in HIV positive patients.