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Many psychological similarities exist between dreams and the symptoms of psychosis, particularly schizophrenia. In both, one can observe hallucinations, delusions, bizarre and implausible thoughts and thought connections, body image distortions, inappropriate affect, loss of volitional control over mental content, loss of the capacity to test reality, loss of volitional control over initiation or termination of an episode, narrowing of the field of consciousness, etc. Because of these mental similarities between dreams and psychoses, it has been suggested that similar brain mechanisms may occur in both. Hence, one search tor physiological correlates of schizophrenia has begun with investigations of dream physiology. As epitomized by Hughlings Jackson, the assumption of these investigations has been: "Find out about dreams and you will find out about insanity."1
In the decade following the early 1950s psychophysiological findings in sleep and dream laboratories stimulated renewed interest in the hypothesis of a dream-psychosis link and, more importantly, made the hypothesis susceptible to empirical testing. First, the pioneering discoveries of Aserinsky, Kleitman, and Dement2,3,4 demonstrated that REM sleep was a reliable physiological correlate of dreaming. In terms of Jacksonian link, this finding suggested the hypothesis that waking schizophrenic symptoms would parallel physiological indications of REM sleep. Second, the finding that the dream-REM sleep state occurred abundantly, frequently, and with clock-like regularity in all studied humans4'5 - indeed, the REM state possessed those properties in all placental mammals"- suggested that REM sleep played a significant but unknown role in the maintenance ol well being. In an attempt to expose this function of REM sleep, Dement deprived subjects ol RHM sleep and observed the effects thereof. "
Subjects were awakened for a few minutes at the start of each REM period tor several consecutive nights. Since the subjects always returned to non-REM sleep after the brief awakening, the procedure made it possible to reduce REM sleep to a small fraction of its original duration. Three effects of this procedure were reported. (1) On successive nights of REM deprivation, there was a progressive increase in the number of awakenings required to deprive subjects of sleep. (2) On the first few nights after experimental REM awakenings stopped, there was more REM sleep (a REM rebound) than before REM deprivation was started. (3) During the days of the...