Effects of Aerobic Exercise in Early Evening on the Following Nocturnal Sleep

Abstract

It is not still established as to whether the nocturnal sleep would be acutely affected by the preceding exercise in daytime. In almost previous studies, in order to evaluate the exercise-induced effect to the quality (i.e. stage) of sleep, the subjects have been taken the sleep under the unusual environment (i.e. laboratory room) for the continuous EEG monitoring. Recently, instead of the constraint EEG monitoring, the estimation method of sleep stage has been developed (as a watch-size device) using the autonomic related index by heart rate variability (HRV) analysis. In addition, while a single bout of exercise is known to elicit acutely a reduction in blood pressure (BP) for approximately 2-3 hours even in healthy subjects (i.e. post-exercise hypotension: PEH), it is unclear as to whether the PEH would be lasting until the bedtime of the following night. PURPOSE: We determined the effect of aerobic exercise in early evening on the quality/quantity of sleep and its hemodynamic response in the following night, not in laboratory, but in subject own room. METHODS: 12 healthy young male subjects (age: 18∼25 yr) participated first in preliminary protocol, in order to check whether he could accustom to equip the ambulatory BP recording device for one day from the early evening to the noon of next day and the special watch for continuous HR recording for bedtime, without exercise intervention. As a result, 10 of 12 subjects had no serious disturbance to usual daily life including the bedtime. Then 10 subjects performed two main protocols either with or without the cycle ergometer exercise (60 min at 50% HR reserve) in early evening (i.e. 1st day), in random order. The ambulatory monitoring of BP/HR (Holter type) and physical activity by accelerometer (AW-16 Actiwatch) were started from the late afternoon (i.e. 30 min before exercise) to the noon of next day (i.e. 2nd day). In addition, the special watch (NEM-T1 Toshiba) for identifying the sleep stage by HRV analysis was equipped during the bedtime. To avoid any effect induced by the food intake, the standardized contents of lunch and dinner of 1st day and breakfast of the 2nd day were offered. RESULTS: There were no substantial differences in sleep objective indices between with and without preceding exercise. Compared to control (i.e. without exercise), the mean values of BP during nocturnal sleep showed a tendency to be lowered by the preceding exercise. CONCLUSIONS: The aerobic exercise in early evening has no certain effect to the sleep acutely, but some beneficial effect to the hemodynamic response during the following nocturnal sleep, i.e. the appearance of prolonged PEH. Supported by JSPS-KAKENHI (#21370111 to YF, #21500689 to AM)