Sleep, the common denominator for psychological adaptation.

Abstract

Honorary President Address (1997) / Allocution du president honoraire (1997)AbstractResearch over the last three decades has increasingly demonstrated that sleep and its various components have a direct impact on many psychological functions such as vigilance, learning, memory, mood and psychological adaptation in general. More recently, the discovery of closer links of circadian rhythms with sleep quality has lead to the development of better intervention methods for adaptation to shift work, circadian phase disruptions and mood disorders (depressions). We present an overview of some of those findings pointing out the contributions of Canadian psychology laboratories. We conclude that more attention should be given to sleep and biological rhythms in research and training in both experimental and applied psychology, as well as in professional practice.The state of sleep occupies one third of a human's life. But despite more than forty years of intensive research, we still do not understand satisfactorily its raison d'etre, its mechanisms nor its control. However, this research has clearly demonstrated that sleep has an impact on many psychological functions that are significant enough for it to be taken into account by researchers and practitioners in psychology in their every day endeavours. We present a sample of observations which should illustrate the importance of sleep factors. In doing so, we will make reference to some of the work of Canadian researchers in psychology which has contributed significantly to this field.SLEEP: AN ACTIVE STATESleep is not just a state of immobility during which physiological functions are restored. Sleep motility is much more pronounced than was previously thought. For example, in the adult, there are typically fifty to sixty body movements taking place during a single night. While the elderly will change positions 10 to 15 times per night, the child can easily change positions sixty times per night (De Koninck et al., 1992). In addition, there can be several instances of night terrors and sleep walking, particularly the young children. Sleep walking can persist in the adult and become very structured and even sometimes dangerous. While incidences of night terrors and sleep walking should not be cause for alarm in the 5 to 12 year old, their persistence in adulthood can be signs of tension that, if not alleviated by stress reduction interventions, need to be addressed by specialists in sleep disorders (Broughton, 1994). Psychological tension is also associated with bruxism and other parasomnias confirming the potential usefulness of psychological interventions.During sleep, there are extreme variations in levels of brain activity which are much more pronounced than during waking. At one end of the spectrum is rapid eye movement (REM) sleep, characterized by EEG activity similar to that of waking. At the other end, slow wave sleep (SWS, stages 3 and 4 in Figure 1) is associated with markedly increased waking threshold, requiring auditory stimuli reaching over 100 db in the child (Busby and Pivik, 1985). The transition between waking and sleep (sleep onset) has been systematically studied both at the electrophysiological and behavioural levels (Ogilvie and Harsh, 1994; Lamarche and Ogilvie, in press; De Lugt et al., in press).We now know that mental activity occurs throughout sleep and is not confined to REM sleep, as is still mentioned in the popular press and even from well recognized professionals. While different types of mental activity typically characterize each sleep stage (see Figure 1), the brain produces mental content of a very varied nature throughout the night (De Koninck, 1994a).THE QUANTITY OF SLEEPThe quantity of sleep that is observed in humans varies with age and there are individual differences of a significant magnitude.We are now able to describe fairly precisely the ontogenetic evolution of sleep in the human. …