1578 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY III 



nun changes the EEG in the direction of wakefulness, 

 though usually very briefly. 



More recently Aserinsky & KJeitman (13) dis- 

 covered that periods of rapid conjugate eye move- 

 ments during sleep wen- associated with episodes of 

 dreaming. Subsequently Dement and KJeitman (55, 

 56) combined the EEG and objective measures of eye 

 movements for the study of all-night sleep. They 

 confirmed the fact that rapid eye movements occur 

 periodically during a night of sleep and that if the 

 subject is awakened during or immediately after the 

 series of eye movements, in 80 percent of the instances 

 he is able to report that he had been dreaming and 

 give the content of the dream. When random awaken- 

 ings were introduced in the absence of eye movements 

 only 7 per cent reported dreaming and in the ma- 

 jority of these instances the time of awakening fell 

 within 8 min. of the last period of eye movements 

 which suggested that the dream was recalled from the 

 previous eye movement period. 



Dement & Wolpert (58) and Dement & Kleitman 

 (57) have greatly extended their observations of eye 

 movements, bodily movement and EEG during 

 sleep, and have determined that there are regular 

 cyclic variations in the depth of sleep as revealed by 

 the EEG and eye movement patterns. Three or four 

 peaks of body and eye movements and sleep light- 

 ened to their stage 1 (comparable to Stage B) occur 

 during a night. Awakening the sleeper during or 

 immediately after one of these periods elicits a report 

 of dreaming. The dream duration appears to parallel 

 the actual eye movement duration which may last 

 from about 10 to 30 min. Contrary to previous 

 belief, the evidence suggests that long dreams are not 

 experienced in a matter of a few near-waking 

 seconds, but rather that the duration of the dream 

 and the duration of the period of lightened sleep and 

 eye movements tend to correspond. Body movements 

 often seem to terminate the dream sequence. The 

 content analysis of the dreams indicates that eye 



movements participate in the dream sequence but 

 that body movements do not. External and internal 



stimuli were found to be unimportant in influencing 



the course of a dream. The 'dream time 1 revealed 

 b\ eye movements appears to correspond with the 

 real oi actual time required to experience or partici- 



pat( in the activity revealed b\ the dream if it were Id 

 be relived in real life The further application of these 



objective methods "i recording eye movements .mil 

 body movements in association with the EE(J, and 



I he correlation of these with the report "1 I lie dream 



upon immediate arousal promises enlightenment 



about the mechanism of dreams where little existed 

 before. 



Is Learning During Sleep Possible? 



Simon & Emmons in a critical review entitled 

 'Learning During Sleep?' (214) raise serious doubt 

 that any of the few published studies, and several 

 unpublished theses, purporting to show that learning 

 can occur during sleep have met the necessary scien- 

 tific requirements which would justify the conclusion 

 that learning has been induced during sleep. After 

 a critical analysis of the experimental design, statistics, 

 methodology and criteria of sleep employed in these 

 studies, Simon & Emmons conclude that all of them 

 had serious weaknesses in one or more of these areas 

 of criticism. They point out that much of the difficulty 

 in evaluating such studies rests upon a definition of 

 sleep, the establishment of suitable criteria of sleep 

 and, perhaps most important of all, whether the 

 period of sleep training was properly monitored 

 throughout to insure that the criteria of sleep were 

 met. 



According to their own apparently carefully 

 controlled experiments, Simon & Emmons (216, 

 217) report that learning did not occur during actual 

 sleep (comparable to Stages C and D discussed above). 

 Even when using a less rigid criterion of sleep based 

 on the transition stage from wakefulness to sleep 

 (comparable to Stage B), but with the restriction that 

 alpha waves be absent from the record at least 30 

 sec. before a stimulus and for at least 10 sec. after- 

 ward, they still found no significant evidence of 

 learning. 



These results would suggest that the best answer 

 that tan In' given at present to this question is that 

 learning dining actual sleep is not possible. Despite 

 this conclusion main commercial enterprises across 

 the country advertise that sleep learning is possible, 

 and oiler phonograph records or tape recordings oi 

 Foreign languages and other dillicult-to-le.irn and 

 time-consuming subjects [o be plaved during the 

 ionise of a night's sleep or some portion of it. 



The important question is whether the user oi 

 such a program of sleep learning is being exposed 

 during waking or near-waking slates in which case 

 the result if positive would not be sleep learning but 

 conscious or semiconscious waking learning. Even 

 though the sleep-learning program were not turned 

 on until an hour or so alter going to bed, we know 

 hum the results discussed above in relation to die. mi 



periods (-,!>, 58) thai there .ne cycles of oscillation 



