Circadian and Sleep-Dependent Processes in Sleep Regulation
When man or animals live in an environment without time-cues, their sleep-wake cycle continues to exhibit a well-defined rhythm whose period (τ) is usually somewhat different from 24 h (e.g. rat: Borbély and Neuhaus 1978, man: Wever 1979). The sleep-wake cycle consitutes therefore a true circadian rhythm which is controlled by an oscillator. Research in circadian rest-activity rhythms is based heavily on motor activity recordings, whereas long-term measurements of sleep have been rarely undertaken. Waking is a prerequisite for motor activity, although motor activity is not always present during waking. Particularly when wheel-running is used as the activity measure, inactivity cannot be equalled to rest or sleep. Long-term recordings of movement activity with a transducer under the animal’s cage provide a close approximation of the sleep-wake rhythm (Borbély and Neuhaus 1978).
KeywordsCircadian Rhythm Sleep Deprivation Sleep Period Slow Wave Activity Sleep Phase
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