Purpose: This experiment examined the influence of prolonged, vigorous late-night exercise on sleep.
Methods: Sixteen highly fit male cyclists completed each of two 60-h laboratory treatments involving a baseline night, an experimental treatment night, and a recovery night. In counterbalanced order, subjects 1) cycled for 3 h at 65-75% of heart rate reserve combined with bright light exposure (3000 lux) light, and 2) were exposed to a 3 h pulse of bright light (3000 lux) alone.
Results: On the baseline and recovery nights, subjects maintained their usual sleep-wake schedules. On the treatment night, exercise + bright light or bright light alone were centered at 6 h before their usual wake times, followed by bedtimes 30 min after the treatments. Illumination was 3000 lux during the experimental treatments, 0 lux during the sleep periods, and 50 lux at other times. Sleep was assessed with an Actillume (Ambulatory Monitoring, Inc., Ardsley, NY) wrist monitor to define sleep onset latency (SOL), wakefulness after sleep onset (WASO), and total sleep time. Subjective assessments of SOL, WASO, and insomnia were also gathered each morning. No significant differences in objective or subjective sleep variables were found between treatments.
Conclusions: These data are inconsistent with the general opinion that vigorous exercise shortly before bedtime disturbs sleep.