ABSTRACT
INTRODUCTION Sleep and circadian physiology change in healthy older adults independent of medical conditions or medications (1-3). In general, deep nonrapid eye movement (NREM) sleep is reduced, there are more awakenings from sleep, and the time spent awake in bed trying to sleep is increased. Such sleep disruptions are exacerbated by age-related diseases such as cardiovascular disease (4), cancer (5,6), nocturia (7), pain (4,8), diabetes (8,9), and depression (10,11). It is estimated that 40% to 70% of older adults experience chronic sleep problems, and that about 50% of the cases are untreated by primary care physicians (12). Sleep problems are even more common in geriatric patients with dementia (13,14). Aging with and without associated medical problems is also associated with changes in the physiology of the internal circadian timekeeping system that regulates near-24-hour rhythms in human physiology and behavior; and age-related changes in circadian physiology are thought to contribute to sleep problems (14-17). This chapter will first review sleep-wakefulness and circadian neurophysiology. Knowledge of the brain regions involved in promoting sleep and wakefulness states can provide perspective on how medications commonly used in the geriatric patient can affect daytime and nighttime function. This discussion will be followed by a review of how sleep and circadian brain regulatory systems change with aging. Knowledge of age-related changes in sleep and circadian systems may promote a better understanding of potential mechanisms underlying sleep problems in the geriatric patient and may help to inform the development of pharmacological and nonpharmacological treatment strategies.
