Influence of exercise on human sleep.

Several research paradigms have been used to examine the influence of exercise on sleep. Epidemiological studies show that exercise is perceived as helpful in promoting sleep and suggest that regular physical activity may be useful in improving sleep quality and reducing daytime sleepiness. Additional epidemiological inquiry is clearly warranted based on the available evidence. Acute exercise experiments that have measured sleep physiology directly from subjects who either performed, or refrained from, daytime exercise indicate that exercise is associated with a small, but reliable increase in Stage 2 and slow wave sleep. The mechanism(s) that underlie exercise-associated increases in SWS is unknown. However, there is evidence that links elevations in daytime core body temperature to increases in SWS. Acute exercise experiments were found to be associated with a reduction in REM sleep and a delay in REM onset latency that were larger in magnitude than the effects observed for Stage 2 and SWS. These REM sleep observations highlight the need for continued study of the consequences of exercise on both circadian and homeostatic aspects of sleep. The delay in REM onset latency observed in the naturalistic acute exercise studies was consistent with the results of experiments in which environmental factors were more rigorously controlled and showed that physical exercise, or a concomitant, can induce a phase delay in markers of the human circadian pacemaker. It is worth pointing out that the most sophisticated and rigorous experiments from a standpoint of understanding sleep, such as those involving constant routines, bed rest, and temporal isolation, have for the most part used exercise in a crude manner. Because exercise is a stressor with diverse psychophysiological consequences that depends in part upon the interaction of multiple factors (e.g., the setting; degree of environmental heat stress; the activity history and fitness of the subject; the duration, intensity, and timing of the exercise bout; body position, etc.), understanding the influence of exercise on sleep will be stymied until carefully designed sleep studies also use exercise in an equally sophisticated and systematic way. Exercise is widely believed to have large effects on sleep. However, the scientific evidence does not strongly support this common belief. This incongruity may well be explained in part by considering the paradigms that have been used to study exercise and sleep.(ABSTRACT TRUNCATED AT 400 WORDS)