Chapter 27 Circadian rhythm sleep disorders

Abstract

Publisher Summary This chapter discusses circadian rhythm sleep disorders. All living organisms from single cells to humans display circadian rhythms in their physiology and behavior. In mammals the circadian pacemaker is located in the specific brain region known as the suprachiasmatic nuclei (SCN). The circadian pacemaker not only synchronizes biological processes to the external environment, but also maintains the temporal organization of these processes to each other. These self-sustaining endogenous circadian rhythms are genetically regulated and persist in the absence of external time cues with a period of approximately 24 hours. The cycle of wakefulness and sleep is one of the most obvious and prominent circadian rhythms in humans. Human sleep–wake behaviors are regulated by a complex interaction of endogenous circadian and homeostatic processes of sleep, as well as environmental factors. The essential feature of a circadian rhythm sleep disorder (CRSD) is a persistent or recurrent pattern of sleep disturbance due primarily to alterations of the circadian time-keeping system or a misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep.