The effects of moderate to vigorous aerobic exercise on the sleep need of sedentary young adults

Exercise has been recommended for enhancing sleep; a claim linked to the belief that sleep need defined by sleep duration and depth is increased post-exercise to allow tissue recovery. Objective studies investigating exercisesleep responses have produced mixed outcomes, and the disparity in results between studies may be due to differences in individual characteristics and/or exercise protocol, emphasising the importance of carefully controlled trials. We investigated the role of exercise on the sleep need of sedentary adults, after controlling for exercise mode, timing and duration. Twelve healthy volunteers (25.2 +/- 4.0 years, 9 females, [Vdot]O2max 35.4 +/- 8.8ml center dot kg1 center dot min1) were randomised to no-exercise or to a bout of treadmill exercise at 45%, 55%, 65% or 75% [Vdot]O2max in a crossover design. Sleep on no-exercise and exercise nights were assessed by polysomnography. Participants spent a greater proportion of sleep in light sleep (stage 1+stage 2) after exercise at both 65% and 75% [Vdot]O2max (P<0.05) than the no-exercise condition. There was a trend of a reduced proportion of rapid eye movement sleep with increased exercise intensity (P=0.067). No other changes were observed in any other sleep variables. Two findings emerged: vigorous exercise did not increase sleep need; however, this level of exercise increased light sleep.