A review of the biological effects of total sleep deprivation in man.

This biologically oriented review attempts to complement earlier and more psychological performance based reviews of total sleep deprivation. Also, the effects of total sleep deprivation are interpreted, here, from a function of human sleep perspective, rather than from the more usual stress viewpoint. It would appear that total sleep deprivation does not produce any major changes in biochemical and physiological measures of somatic functioning. Such a conclusion would not seem to support an hypothesis that human sleep is for body restitution. Although there are equivocal results amongst several of the more psychophysiological measures, EEG does show a pronounced change. This latter finding, together with many reports of psychological performance detriment, would appear to sustain a CNS or cerebral restitutional role for human sleep. However, before definitive conclusions can be drawn from the biochemical and physiological findings of total sleep deprivation, the following qualifications of experimental methodology are made: (1) Apart from sleep loss, many studies have provided unnatural regimes which may have ameliorated possible effects of total sleep deprivation. (2) Most studies are of relatively short duration and may not have been sufficiently long for effects to develop. (3) Measures are often limited in range and depth of analysis. (4) Subjects are mostly fit, young adult, intelligent males and there is little constitutional variability. (5) Reported changes of statistical significance may be of no physiological significance and changes of possible physiological significance may be obscured by statistical procedures. (6) Intervening behavioural variables, such as novelty and anticipation of the sleep deprivation situation, may confound real effects.