Exercise before bed is linked with disrupted sleep

Summary

Actual exercise timing and strain associations with sleep and nocturnal autonomic activity. Credit: Nature Communications (2025). DOI: 10.1038/s41467-025-58271-x Exercise too close to bedtime may affect sleep duration, timing and quality, new research led by Monash University has found. More strenuous workouts closer to bedtime coincided with greater disruptions to sleep and nighttime cardiac activity. Published in Nature Communications, the study found that exercising four hours or less before bedtime was linked to falling asleep later, getting less and worse quality sleep, and having a higher resting heart rate and lower heart rate variability. It is the first and largest study to identify this. The study involved an international sample of 14,689 people monitored across one year, resulting in four million nights of data. They wore a multi-sensor biometric device (WHOOP Strap) to record exercise, sleep and cardiovascular data. Monash and WHOOP researchers examined the relationships between evening exercise, exercise strain, sleep and nocturnal cardiac activity, including resting heart rate and heart rate variability. The combination of later exercise timing and higher exercise strain was associated with delayed sleep onset, shorter sleep duration, lower sleep quality, higher nocturnal resting heart rate and lower nocturnal heart rate variability. The results were adjusted for gender, age, weekday, season, general fitness and the prior night's sleep. High strain exercise includes activities that lead to sustained increases in breathing rate, core body temperature, heart rate and mental alertness. Examples include HIIT workouts (high-intensity interval training), football and rugby games or a long run. First author Dr. Josh Leota, from the Monash University School of Psychological Sciences, said he wanted to shed light on "the important yet puzzling" link between the timing of exercise and sleep. "Intense exercise in the evening can keep the body in a heightened sta...