Sleep and Circadian Development in Adults and Older Adults

Abstract This chapter reviews age-related changes in sleep, circadian rhythms, and sleep disorders in adults and older adults. With advancing age there are major changes in sleep, including sleep timing, the amount of slow-wave sleep, the number of nocturnal awakenings, sleep consolidation, and total sleep time. There are also changes in circadian rhythmicity with aging, including a reduced amplitude of some circadian rhythms and some evidence for reduced sensitivity to light. The interaction between the sleep and circadian regulatory systems also changes with age, resulting in greater difficulty sleeping during the biological daytime, the nocturnal sleep episode occurring at earlier circadian phases than in young adults, and a reduced ability to obtain a long and consolidated sleep episode. In addition to these general changes in sleep and circadian rhythmicity with aging, the sleep of many older people is impacted by a higher prevalence of specific sleep disorders, including obstructive sleep apnea, periodic limb movements of sleep, and rapid-eye-movement behavior disorder; and they are also more likely to have chronic medical problems that interfere with sleep and to take medications that either disrupt nighttime sleep or impact daytime alertness.