SLEEPWALKING IN SOMNAMBULISM - EFFECT OF AROUSALS, DEEP SLEEP AND SLEEP-STAGE SHIFTS

Diagnosis of parasomnias in the sleep laboratory is difficult since th e nocturnal behavior reported by the patients often does not show up i n the laboratory.To test the efficacy of sleep deprivation as a tool t o provoke somnambulism we investigated ten patients (three women and s even men,mean age 27+/-3.4) with somnambulism.Their standard polysomno graphies and videomonitored nocturnal behavior was compared to that of sex- and age-matched controls and to polysomnography and behavior aft er sleep deprivation. Patients with parasomnias and controls did not s how significant differences in sleep parameters with the exception of longer arousal duration in controls,which was nonsignificant. In magne tic resonance tomography, patients with parasomnias did not reveal abn ormality of the brain that might explain release of nocturnal behavior .Sleep deprivation led to significantly reduced number of arousals, re duced arousal index,significantly prolonged arousal duration and more stage shifts from all sleep stages (nonsignificant).Complex behavior d uring sleep increased under sleep deprivation,whereas sleepwalking did not increase.The majority of complex behavior during sleep is trigger ed by stage shifts and not by arousal in the sense of the arousal defi nition of the American Sleep Disorder Society. Complex behavior in sle ep is stereotypical and nonviolent. Its complexity seems to depend on the duration and intensity of arousals.Sleep deprivation can be recomm ended as an efficacious method of increasing complex behavior in sleep ,which is a preliminary stage of sleepwalking.Concerning the underlyin g pathology it seems to be important to register the quality and durat ion of stimuli that trigger arousals instead of focusing the number of arousals alone.