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Have you ever wondered how the timing and intensity of your workout could be affecting your sleep? A recent Nature Communications study led by Elise Facer-Childs and her team at Monash University dives into this question, shedding light on the intricate relationship between evening exercise and sleep. Despite the wealth of previous research on evening exercise, the specific impact of different combinations of exercise intensities, durations, and timings before sleep has not been studied – until now.

First author Josh Leota and the team analyzed wearable data from over 14,000 physically active individuals over the one year of the study. The data collected included detailed records of exercise habits, such as the time of day and the duration of physical activity, as well as comprehensive sleep metrics. Continuous heart rate measurements during each exercise bout were used to categorize the intensity of the activity.

The study revealed nuanced insights into how different exercise patterns impact sleep. Exercising within a four-hour window of sleep onset was correlated with a delay in sleep, and exercise bouts ending closer than six hours of bedtime were associated with shorter sleep durations. Within these time windows, higher exercise strain, a measure of intensity and duration, showed a greater impact on sleep onset and duration than light or moderate exercise strain. These findings highlight the importance of exercise timing, intensity, and duration in minimizing its potential drawbacks on sleep.

Based on these findings, the researchers recommend scheduling high-intensity workouts at least four hours before bedtime to allow the body sufficient time to return to a more restful state. If it is necessary to exercise right before bedtime, choose lighter strain exercises to minimize disruptions to sleep duration.

The study is part of a Wu Tsai Human Performance Alliance Agility Project.

Co-authors include Josh Leota, David M. Presby, Flora Le, Mark É. Czeisler, Luis Mascaro, Emily R. Capodilupo, Joshua F. Wiley, Sean P. A. Drummond, and Shantha M. W. Rajaratnam.

The initial draft of this article was generated using GPT-4o, May 29, 2025.

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