HOMESTATIC FACTORS IN AGE RELATED SLEEP DISTURBANCE

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Age-related changes in sleep physiology lead to reduced nighttime sleep durations in individuals over 65 years of age. Nighttime sleep amounts are decreased by an average of approximately 2 hours when compared to young adults. The consequences of curtailed sleep amounts include a decreased quality of life, particularly with respect to reductions in daytime performance and mood. A number of approaches have been taken in an attempt to increase sleep quality (e.g., consolidation, circadian placement) with varying levels of success. The goal of substantially increasing total sleep time has been less successful, perhaps due to a reduced capacity of the aging sleep system to achieve additional sleep time at night. Although increasing nighttime sleep durations may be difficult in this older population, it may be quite possible to increase twenty-four hour sleep amounts by taking advantage of the robust biological tendency to sleep at a specific phase of the waking day. Our recently completed study, for which the current proposal is a COMPETING CONTINUATION, supports previous work indicating that older individuals can, indeed, respond to this second preferred phase position for sleep and can obtain significant amounts of sleep during the daytime. Importantly, these and other data also strongly suggest that such daytime sleep episodes do not negatively affect nighttime sleep. Finally, there is strong evidence that napping can significantly improve cognitive and psychomotor performance, both acutely and for many hours following the nap. The proposed project will employ a within-subjects, counterbalanced design to evaluate the effects of a strategically placed nap opportunity on cognitive and psychomotor performance levels and mood in older individuals. It is hypothesized that, relative to the no-nap condition, a nap opportunity near the time of the circadian temperature maximum will result in a significant increase in 24-hour sleep amounts, and will not affect the subsequent nighttime period. Further, the increase in sleep amounts will lead to improved performance and mood both immediately following the nap and throughout the next day. This study is viewed as the first step towards the development of a natural and easy-to-implement strategy for supplementing the sleep of older individuals, with the resulting benefits of enhanced waking function and improved quality of life.