Ontogenetic Development of the Human Sleep-Dream Cycle

Abstract

Whereas respiratory rhythm, heart rate, and blood pressure tend to be basal in NREM sleep, they display greater activity and greater variability during REM phases (3-5, 11, 12, 31). The fine muscles of the face and extremities contract frequently, though there are few gross body displacements (14). In the absence of movement, however, muscle tone measured from the head and neck virtually disappears in REM periods (20, 32). The extrinsic ocular muscles are an exception to this rule. Before and during shifts of eyeball position, tone may be sustained in uninvolved and antagonist muscles (33). Penile erections are specific to the REM periods, detumescence occurring as NREM sleep ensues (34). Basal skin resistance, which should fall with heightened arousal, has been reported to rise in REM sleep by some investigators (35) but not by others (11, 30). In view of the eye activity and oneiric phenomena during REM sleep, it is intriguing that the REM sleep EEG is remarkably similar to that of a subject awake under circumstances of visual imaging or stimulation, when alpha activity is blocked. Furthermore, cortical responses evoked during the waking state are extremely similar to those evoked in REM sleep (36).An unexpected finding has been that motor-response and arousal thresholds are no higher in deep NREM sleep than in REM sleep (5, 37). This seems to fit with the finding in cats that during REM sleep there is a high response threshold in the mesencephalic reticular formation to auditory (38) as well as to direct stimulation (39, 40). In spite of the lowered responsiveness to stimulation, however, there is greater spontaneous activity in the reticular formation during REM sleep (39). (It is precisely this aspect of brain functioning in REM sleep which renders "depth of sleep" so difficult to designate.) Huttenlocher has speculated that in REM sleep evoked responses may be occluded because of this high level of spontaneous activity. Recently, however, Adey et al. (41) were not able to demonstrate higher response thresholds in the mesencephalic reticular formations of chimpanzees during REM sleep. Studies in AnimalsA dual neurophysiological organization of sleep is not specific to human beings. Every species of mammal so 29 APRIL 1966 far studied exhibits rhythmically alternating periods of REM and NREM activity which are marked by vegetative alterations similar in most respects to those that are found in man (12, 41-52).Moreover, animal experimentation has greatly extended our knowledge of the active processes occurring in the central nervous system during the REM state, such as: increase in blood flow to the cortex (47); rise in brain temperature (52); elevation in frequency of spontaneous neuronal firing in the MRF (39), medial and descending vestibular nuclei (53), pyramidal tract (54, 55), and occipital cortex (56); development of monophasic wave aggregates in the pons, lateral geniculate body, and other subcortical areas; continuous theta activity in the hippocampus (even more regular than during arousal) (9, 51...

Rem sleep, early experience, and the development of reproductive strategies

“…13#4 160943 postnatal weeks, becomes the predominant sleep state in the infant for several weeks, and then starts a slow decline relative to NREM until adult values are reached in late adolescence. This phenomenon of abundant REM early in life holds across all mammalian species studied to date, and thus many authorities on REM assert that REM's primary function(s) must be developmental in nature (Mirmiran 1995;Roffwarg et al 1966). …”

The development of potentially better practices to support the neurodevelopment of infants in the NICU

“…With maturation, there is a gradual shift towards adult sleep-wake cycles, and a marked decrease in sleep requirements, with relatively less REM sleep with age. 74 This association of extended REM sleep during a period of rapid brain maturation, stabilizing to adult levels with brain maturity, is demonstrated in animals as well. 66 Human newborns have large requirements for REM sleep.…”

“…The 'ontogenetic hypothesis' theorizes that normal sleep cycles, with a predominance of REM sleep, are necessary for early brain development. 74,75 Roffwarg observed a great need for sleep in the infant, especially REM sleep. With maturation, there is a gradual shift towards adult sleep-wake cycles, and a marked decrease in sleep requirements, with relatively less REM sleep with age.…”

“…Young adult levels of REM sleep, about 20%, are not reached until preschool age, and gradually decrease to <15% at maturity. 68,74,76,77 Of note, whereas there is about an 80% decrease in REM, there is only about a 25% decrease in NREM sleep over the lifetime of humans. With maturation, there appears to be a shift from a predominance of REM sleep towards a balance of REM and NREM sleep states, and this emergence of NREM sleep seems to parallel the maturational stage where there is a critical need to integrate external stimuli.…”

Constructing visual function through prenatal and postnatal learning

“…Developing embryos spend a large percentage of their time in a primitive form of REM sleep, which suggests that this state has a major role in development (Roffwarg, Muzio, and Dement 1966). During REM sleep, PGO waves originate in the brain stem, then travel to the LGN, visual cortex, and many other brain areas (see Callaway, Lydic, Baghdoyan, and Hobson 1987 for a review).…”