The parasomnias are important yet badly recognised dysfunctions in clinical psychiatry. The clinical presentation and consequences in adults differ considerably from the often benign dysfunction in childhood. We present a case of incubus in a patient suffering from recurrent unipolar affective psychosis (type mania). The polysomnographic features are discussed and the differentiation from other paroxysmal amnestic conditions is emphasized. Pathophysiology encompasses a Slow Wave Sleep (SWS) arousal disorder probably related to a serotoninergic dysfunction. The relationship withpsychopa-thology is discussed.
