AEROBIC FITNESS, ACUTE EXERCISE AND SLEEP IN OLDER MEN

In the current study 12 aerobically fit and 12 sedentary older men und erwent two nocturnal polysomnographic (PSG) studies. A control PSG was conducted following a day without aerobic activity, whereas a postexe rcise PSG study was conducted following an afternoon session of exhaus tive aerobic exercise. In addition to deriving usual sleep parameters, a computer scoring program was used to count the number of individual electroencephalographic (EEG) slow waves in each PSG tracing. Multiva riate and univariate analyses showed that the fit subjects had shorter sleep onset latencies, less wake time after onset, fewer discrete sle ep episodes, fewer sleep stage shifts during the initial portion of th e night, less stage 1 sleep, a higher sleep efficiency and more total slow waves during both PSGs than did the sedentary subjects. Although no main effects were found for the acute exercise challenge, post hoc analyses showed that high levels of body heating during exercise predi cted increased sleep fragmentation for both fit and sedentary subjects . These findings provide initial support for the contention that exerc ise and fitness may have significant effects on the sleep of older men . However, results also suggest that high levels of body heating resul ting from a single exercise challenge may have adverse effects. Implic ations of the study are discussed and suggestions for future research are provided.