Late-Night Workouts May Harm Your Sleep, New Study Suggests

As reported by The Washington Post, a new university-led study is raising concerns for night-time fitness enthusiasts: exercising too close to bedtime—especially if it’s intense—can significantly disrupt your sleep.

According to research from Monash University in Australia, recently published in Nature Communications, exercising within four hours of going to sleep can lead to difficulty falling asleep and cut sleep duration by as much as 43 minutes. The findings were based on data from over 14,000 men and women who wore Whoop fitness trackers for at least a year. While Whoop provided the data, it had no influence over the analysis, the researchers clarified.

Dr. Josh Leota, the study’s lead author, told The Washington Post that he’s changed his own habits since the findings: “I do my best now to avoid exercising late in the evening.”

The study found that late and intense workouts were the most disruptive. For instance, those who engaged in high-effort exercise like soccer, basketball, or running late at night took an average of 36 extra minutes to fall asleep. If the workout occurred even after their typical bedtime, the delay in sleep onset increased to 80 minutes. Participants also experienced more restless nights and shorter overall sleep.

The disruptions, according to tracker data, were likely linked to elevated heart rates and reduced heart rate variability after evening exercise—both signs that the body remained physiologically alert even hours after working out.

While the findings don’t prove causation, they support existing sleep science. Kenneth Wright Jr., a sleep researcher at the University of Colorado, who was not involved in the study, told The Post the results strengthen current recommendations: “To promote sleep health, a general recommendation to avoid intense exercise within four hours of bedtime is warranted.”

For those who must exercise in the evening, the study—also highlighted by MSN—suggests winding down with calming routines like yoga or meditation and keeping workouts light when possible. But Dr. Leota emphasized that any exercise is still better than none: “We are definitely not discouraging exercise,” he said.

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