WHOOP Data Reveals Strenuous Evening Workouts May Disrupt Sleep Quality
Krissy Vann | Host, All Things Fitness and Wellness
A new international study has found that exercising too close to bedtime, particularly if the workout is intense, may interfere with how well you sleep. The research, led by Monash University and published in Nature Communications, is the largest of its kind to explore how the timing and intensity of evening workouts affect sleep and nighttime heart function.
The study analyzed data from 14,689 physically active individuals over the course of a year, capturing more than 4 million nights of sleep using WHOOP biometric tracking devices. These devices recorded details about each participant’s exercise habits, sleep patterns, and cardiovascular activity in everyday, real-world conditions.
Researchers found that exercising within four hours of bedtime, especially at high intensity, was linked to going to sleep later, reduced sleep duration, and lower quality rest. These late-night workouts were also associated with higher resting heart rates and lower heart rate variability throughout the night. Both are signs that the body remains in a heightened state of alertness and has not yet transitioned into recovery mode.
The study defined high strain workouts as those that significantly elevate heart rate, core body temperature, breathing rate, and mental alertness. Examples include HIIT classes, long runs, or competitive sports such as football and rugby. Even after adjusting for age, gender, general fitness, and other factors, the connection between strenuous evening exercise and disrupted sleep remained clear.
However, not all evening exercise appeared to have negative effects. Lighter or moderate workouts that ended at least two hours before bedtime did not significantly impact sleep timing or quality. This suggests that activities like walking, stretching, or low-intensity cycling may still be suitable in the evening for those who prefer to work out later in the day.
The findings carry important implications for both regular exercisers and professional athletes. Sleep plays a critical role in recovery, and ongoing disruption can impact mood, energy, and long-term health. For those unable to shift their workout schedule earlier, choosing lower-intensity evening exercise may help reduce the impact on sleep.
Ultimately, the study highlights that both the timing and intensity of exercise influence how well we sleep. Experts recommend finishing high-intensity workouts at least four hours before bedtime to allow the body sufficient time to wind down and prepare for rest.
Credit: Studio Pilates