Somnambulistic-like episodes secondary to combined lithium-neuroleptic treatment

Ten of 114 psychiatric patients undergoing combined lithium-neuroleptic treatment exhibited somnambulistic-like episodes. These episodes are differentiated from nocturnal wanderings and epileptic attacks during sleep; they occurred within two to three hours after sleep onset and were characterized by the patients appearing confused and walking about in a quiet, detached and clumsy manner. Generally, there was amnesia for the event. Since sleepwalking occurs out of slow wave sleep, the increase in slow wave sleep induced by lithium and certain neuroleptics may represent a neurophysiological mechanism responsible for these patients' somnambulistic behaviour. The occurrence of grand mal seizures in two patients was probably unrelated to the somnambulistic-like episodes. However, persistence of the latter appears to be associated with drug-induced EEG irregularity.