Acute exercise leads to a moderate delay in the on set of REM sleep,a small decrease in the amount of REM sleep,and a small increase in SWS and total sleep time-amomg good sleepers. The biggest limitation of studies of the effects of exercise on sleep had been a focus on good sleepers. Convincing studies using polysomnographic measures of sleep after chronic exercise,among initially sedentaty people who are poor sleepers,have not beem conducted.The small number of studies on chronic