ABSTRACT
This chapter outlines knowledge regarding the neurobiological regulation of sleep and circadian rhythms and the effects on fatigue and performance. Although the exact function of sleep is debated, sleep deprivation studies have shown that lack of sleep increases fatigue, produces decrements in neurocognitive performance and degrades physiological functioning. Humans like all organisms, show changes in their biology and behavior that are not just controlled by external environmental stimuli, but are driven by internally generated cycles. The underlying neurobiology is relatively well known with respect to the circadian system, and the subcortical mechanisms initiating and terminating sleep are also well understood. Neuroimaging techniques such as positron emission tomography and functional magnetic resonance imaging have significantly advanced the ability to study brain function during sleep and waking. At the behavioral level, however, sleep and circadian rhythms have been characterized in sufficient detail to be able to anticipate their overall effects on fatigue and performance.
