The Effects Of Exercise Timing On Sleep

Abstract

Epidemiological research has linked sleep quality with exercise, but few prospective studies have examined if exercise improves sleep quality and if the timing of the exercise impacts sleep. PURPOSE: To determine if exercise timing differentially affects sleep quality in men and women. METHODS: Thirty subjects wore an Actiwatch (Actiwatch 2, Phillips Respironics), which measured sleep duration, sleep efficiency and wake after sleep onset (WASO) for three consecutive nights at home, followed by a testing day of either no exercise (NOEx), morning exercise (AMEx), or nighttime exercise (PMEx). Morning exercise occurred at 0700 h and the nighttime exercise occurred at 2000 h on the respective study night. For each exercise bout, the subject exercised on a treadmill at 55% of their VO2max for 45 minutes. The order in which they completed each condition was randomized, and study nights were separated by about one month. For the study nights, subjects arrived at the hospital at 1700 h and were given a standard meal at 1800 h. Lights were turned off by 2230 h and turned back on at 0700 h. RESULTS: Sleep duration significantly increased on the study nights (7.9±0.16 h) compared to the nights of sleep at home (7.4±0.13 h, p=0.02), but was not affected by exercise. There were no differences in the sleep efficiency between study nights (84.8±1.6%) and non-study nights (83.4±1.1%, p=0.33) or between exercise conditions; NOEx (82.0±2.2%), AMEx (85.7±1.1%), and PMEx (84.5±1.5%, p=0.14). WASO was not different by study nights (0.8±0.13 h) and non-study nights (0.7±0.09 h, p=0.15), or between exercise conditions; NOEx (0.87±0.21 h), AMEx (0.55±0.5 h), and PMEx (0.78±0.22 h, p=0.14). CONCLUSIONS: Sleep quality was maintained from the home setting to the research setting. Exercise did not improve sleep duration, efficiency or WASO in our subjects between the exercise and no exercise day and exercise timing had no effect on these variables.