Diurnal repeated exercise promotes slow-wave activity and fast-sigma power during sleep with increase in body temperature: a human crossover trial

The effects of exercise on sleep have been explored from various perspectives, but little is known about how the effects of acute exercise on sleep are produced through physiological functions. We used a protocol of multiple daytime sessions of moderate-intensity aerobic exercise and examined the subsequent effects on sleep structure, core body temperature (CBT), distal-proximal skin temperature gradient (DPG), and subjective parameters. Fourteen healthy men who did not exercise regularly were evaluated under the baseline (no exercise) and exercise conditions on a within-subject crossover basis. Under the exercise condition, each participant performed a 40-min aerobic workout at 40% of maximal oxygen intake, four times between morning and early evening. We observed a 33% increase in slow-wave sleep (SWS; <i>P</i> = 0.005), as well as increases in slow-wave activity (SWA; <i>P</i> = 0.026), the fast-sigma power/SWA ratio (<i>P</i> = 0.005), and subjective sleep depth and restorativeness the following morning. Moreover, both CBT and the DPG increased during sleep after exercise (<i>P</i> = 0.021 and <i>P</i> = 0.047, respectively). Regression analysis identified an increased nocturnal DPG during sleep after exercise as a factor in the increase in SWA. The fast-sigma/SWA ratio correlated with CBT. The performance of acute exercise promotes SWS with nocturnal elevation in the DPG. Both CBT and fast-sigma power may play a role in the specific physiological status of the body after exercise. <b>NEW & NOTEWORTHY</b> We used multiple daytime sessions of moderate-intensity aerobic exercise to examine the effects on the sleep structure, core body temperature (CBT), distal-proximal skin temperature gradient (DPG), and subjective parameters. Significant increases in slow-wave activity (SWA), CBT, DPG, fast-sigma power, and subjective parameters were observed during the night and the following morning. Nocturnal DPG is a factor in the increased SWA.