Daan et al. (1984) have proposed that sleep and wakefulness are regulated, in part, by a "Process S" that increases during wakefulness and declines during sleep. Data derived from several studies were taken to determine the time course of Process S during both wake fulness and sleep. As required by the model, slow-wave-sleep (SWS; an index of Process S) was found to increase exponentially as a function of prior wake time (equation 1) and to decline exponentially as a function of time asleep (equation 2). The equations accounted for 91% and 96% of the variance, respectively. In addition, equation 1 accurately predicted the amount the amount of SWS in the first hour of nocturnal sleep.
References
1.
Agnew, H.W., and W.B. Webb (1973) The influence of time course variables on REM sleep. Bull. Psychonom. Soc. 2 : 131-133.
2.
Borbély, A.A. (1982) A two process model of sleep regulation. Human Neurobiol. 1: 195-204.
3.
Daan, S., S.D.G. Beersma, and A.A. Borbély (1984) Timing of human sleep: Recovery process gated by a circadian pacemaker. Amer. J. Physiol. 246: R161-178.
4.
Hume, K.I., and J.N. Mills (1977) Rhythms of REM and slow-wave sleep in subjects living on abnormal time schedules. Waking and Sleeping1: 291-296.
5.
RECHTSCHAFFEN, A., and A. KALES, eds. (1968) A Manual of Standardized Terminology, Techniques and Scoring System for Sleep Stages of Human Subjects , U.S. Department of Health, Education and Welfare, Washington, DC.
6.
Webb, W.B., and H.W. Agnew (1971a) Stage 4 sleep: Influence of time course variables . Science174: 1354-1356.
7.
Webb, W.B., and H.W. Agnew (1971b) Variables associated with split-period sleep regimes. Aerospace Med. 42 : 847-850.
