Effects of a nap on nighttime sleep and waking function in older subjects

OBJECTIVES: To examine, in older subjects, the effect on waking function of increasing 24-hour sleep amounts by providing a nap opportunity; to assess what effects an afternoon nap may have on subsequent nighttime sleep quality and composition. DESIGN: Two-session, within-subject laboratory design. SETTING: The study was conducted in the Laboratory of Human Chronobiology at Weill Cornell Medical College. PARTICIPANTS: Thirty-two healthy men and women aged 55 to 85. MEASUREMENTS: Polysomnography (sleep electroencephalogram), cognitive and psychomotor performance, body core temperature. RESULTS: Napping had little effect on subsequent nighttime sleep quality or duration, resulting in a significant increase in 24-hour sleep amounts. Such increased sleep resulted in enhanced cognitive and psychomotor performance immediately after the nap and throughout the next day. CONCLUSION: A behavioral approach that adds daytime sleep to the 24-hour sleep quota seems worthy of consideration when presented with a situation in which physiological changes associated with aging may limit the duration of nighttime sleep.