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vot remaining 21 (28%) as WIA pHoMed hgecRaimas aa NW/08/08 : Cl “RDP SCO TARRA0SER 044009 1B ributed within REM periods and than WILDs (binomial test, p < .0001). Compared to DILDs WILD: more frequently immediately preceded by physiological indications of a ing (Chi-squared = 38.3, | df, p < .0001), establishing the validit, ing lucid dreams in this manner. See Figures 2 and 3 for illustrati types of lucid dreams. The distributions of DILD and WILD Jatencies from the onset of REM significantly different (LaBerge, Levitan, & Dement, 1986). A Wald-w. * test demonstrated that WILDs do not occur a DILDs do (p < .0015). This difference may be simply explained: As a m definition, a necessary condition for a WILD to occur is a transitory awaken; followed by a return to REM sleep. If the awakening were to happen too near the beginning of REM, the REM period might simply be aborted. Similarly. the awakening were to occur too near to the ‘‘natural’’ end of the REM periog " would be more likely that REM would not resume but that wakefulness wor, } persist or a NREM sleep stage would ensue. , oud To summarize, an elevated level of CNS activatio Te ; m seems to be a neces; condition for the occurrence of lucid dreams. Were this condition unnecessary. Tg on ee 14 ~- ROC eye ROC+| 4 ~~~ 4 we et ECG 444. re) 4 AAAI ALA aL AALS Figure 3. A typical lucid dream initiated from a transient awakening during REM (WILD). Six channels of physiological data (left and right temporal EEG [T, and T,], left and right eye movements [LOC and ROC], chin muscle tone [EMG], and electrocardiogram [ECG]) from the ast 3 min of a 14-min REM period are shown. The subject awoke at 1 and after 40 seconds returned to REM sleep at 2, and realized he was dreaming 15 s later and signaled at 3. Next he carried out the agreed-upon experimental task in his lucid dream, singing between signals 3 and 4, and counting between signals 4 and 5. This allowed comparison of left and right hemisphere activation during the two tasks (LaBerge & Dement, 1982b). Note the heart-rate acceleration-deceleration pattern at awakening (1) and at lucidity onset (3) and the skin poten” tial tential artifacts in the EE particular ly T at lucidity onset Calibrations are 50 | S Were f Waken. “tCKY Of classify. ons of these two _. ' om lfowit, t occur as early or late in REM periods as atter of eee A la rR haps every stage of sleep. Why then is CNS activation necessary for lucid d reaming? Evidently the high level of cognitive function involved in lucid dreaming requires 2 correspondingly high level of neuronal activation. In terms of Antrobus’s (1986) adaptation of Anderson’s (1983) ACT* model of cognition to dreaming. working memory capacity is proportional to cognitive activation, which in turn is proportional to cortical activation. Becoming lucid requires an adequate level of working memory to activate the presleep intention to recognize that one IS dreaming. This level of activation is apparently not always available during sleep but normally only during phasic REM. THE TEMPORAL DISTRIBUTION OF LUCID DREAMS St. Thomas Aquinas mentioned “‘that sometimes while asleep a man may judge that what he sees is a dream, discerning as it were, between things and their images” and that this happens especially ‘‘towards the end of sleep, in sober men and those who are gifted with a strong imagination.” (Aquinas, 1947, p. 430). Van Eeden (1913) stated that his lucid dreams invariably occurred between 5 and 8 o'clock in the morning. By way of explanation, he quoted Dante’s characterization of these hours as the time ‘‘when swallows begin to warble and our mind is least clogged by the material body.’’ Garfield (1975) exactly agreed with van Eeden’s observation, though perhaps not with his poetic explanation. LaBerge (1979) plotted the times of 212 of his lucid dreams and found their pattern of occurrence closely fit the usual cyclic distribution of REM periods. He suggested that the fact that most REM sleep occurs toward the end of the night provided a plausible explanation for Van Eeden’s and Garfield's obser- vations. Later, LaBerge (1980a) tested this hypothesis by comparing the tem- poral distribution of his lucid dreams with that expected on the basis of normative data from Williams, Karacan, and Jursch (1974). A chi-square test indicated that the observed distribution of lucid dreams in the first three REM periods was not significantly different from what would be expected on the basis of mean REM period lengths at different times of the night. Cohen (1979) argued that the left hemisphere shows a gradual increase in dominance across the night (but see Armitage, Hoffmann, Moffitt, & Shearer, 1985). Since left-hemisphere abstract symbolic functions are undoubtedly crucial for lucid dreaming, Cohen’s GILD hypothesis led LaBerge (1985b) to predict that the probability of dream lucidity should increase with time of night. This hypothesis was tested by LaBerge et al. (1986). For each of their 12 subjects, a median split for total REM time was determined, 11 of their subjects had more lucid dreams in the later half of their REM than in the earlier (binomial test; p < .01). For the combined sample, relative lucidity probability was calcu- lated for REM periods | through 6 of the night by dividing the total number of Approved For Release 2000/08/08 : CIA-RDP96-00789R003100140001-2