Effect of time-of-day of aerobic maximal exercise on the sleep quality of trained subjects

This study was designed to assess the effects of time-of-day of maximal aerobic exercise on the subsequent sleep of trained subjects. Twelve subjects (22.6 +/- 2.1 years, 178 +/- 4.4 cm and 72.2 +/- 6.3 kg) completed the Yo-Yo intermittent-recovery-test level 1 (YYIRT) at 14:00 and 20:00 h. Then, sleep polysomnography was recorded from 22:00 to 07:00 h. Oral temperature was measured before and after the YYIRT and the sleep period. Performance during the YYIRT was not statistically different between afternoon and evening. However, core temperature was significantly higher in the evening than afternoon before (p < 0.05) and after (p < 0.01) the YYIRT. Moreover, sleep-onset-latency, number-of-awakenings, slow-wave-sleep and rapid-eye-movement-sleep-latency were significantly higher after the evening test session (p < 0.05). However, time-in-bed, total-sleep-time, rapid-eye-movement-sleep and sleep-efficiency were higher after the afternoon test session (p < 0.05, p < 0.001, p < 0.01 and p < 0.01 respectively). In conclusion, maximal aerobic exercise performed later in the evening is "worse" than training in the afternoon and might result in a markedly poor subsequent sleep quality (disturbing and fragmenting sleep).