ABSTRACT
Sleep and wakefulness are among the basic instinctual behaviors that are expressed in its present form by living species high in the evolutionary ladder. Both sleep and wakefulness are active processes regulated by the brain. However, they may also be modulated by a large number of psychosomatophysiological as well as environmental factors. In spite of unanimity among the experts that sleep is essential, the window for the daily requirement of sleep is fairly wide. Although it is known that loss of sleep adversely affects several physiological, behavioral, and psychological parameters, the detailed function(s) of sleep are as yet unknown (see also Chap. 1).
