Evening workouts might seem convenient, but they could be sabotaging your sleep more than you realize.

Quick Take

• Exercising less than four hours before bed disrupts sleep quality.
• High-strain activities like HIIT or rugby exacerbate sleep issues.
• A study by Monash University analyzed over 4 million nights of data.
• Findings challenge earlier lab-based research on evening exercise.

Exercise Timing and Sleep Quality

Monash University’s 2025 study revolutionized our understanding of exercise timing by using data from 14,689 participants over one year. The research demonstrated that engaging in physical activities four hours or less before sleep leads to delayed sleep onset, shorter sleep duration, and reduced quality. The use of WHOOP wearable technology provided a robust dataset, allowing researchers to link exercise timing and strain directly to cardiac sleep metrics.

The Impact of High-Strain Activities

High-intensity workouts, such as high-intensity interval training (HIIT) and rugby, were found to significantly impact sleep more than low-intensity activities. These exercises cause sustained arousal in breathing, body temperature, and heart rate, leading to increased alertness and disrupted sleep. The findings support a shift in public health guidelines, advocating for a minimum four-hour buffer between high-strain exercise and bedtime to ensure better sleep quality.

Moderate and low-intensity exercises performed closer to bedtime may have mixed outcomes, depending on individual tolerance and fitness levels. These insights urge gym-goers and athletes to reconsider their evening workout schedules to enhance their recovery and overall well-being. Chat safely, anytime, with My Healthy Doc.

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Public Health Implications

Public health bodies are now considering updates to exercise guidelines based on these findings. The study’s large-scale, real-world data contrasts with previous lab-based studies, which often relied on smaller sample sizes and less intense exercises. As a result, health agencies may soon recommend against late-night high-strain workouts to combat sleep disorders and improve population health.

The implications extend to fitness communities and gym users who are encouraged to optimize their routines by balancing their exercise and sleep schedules. By adopting these new recommendations, individuals can potentially reduce sleep disturbances and improve their overall health and productivity.

Moreover, the wearable technology industry, exemplified by WHOOP, is likely to benefit from these findings as demand for data-driven fitness and sleep optimization increases. The convergence of fitness and technology continues to offer new insights into personal health management. Got a health question? Ask our AI doctor instantly, it’s free.

Avoid high intensity exercise 4 hours before sleep pic.twitter.com/2L4u7l7GTJ

— Bryan Johnson (@bryan_johnson) July 16, 2025

Sources:

Exercise before bed is linked with disrupted sleep: study
Understanding the Relationship Between Exercise and Sleep
Saudi Study Highlights Exercise-Sleep Disruption
The Impact of Evening Exercise on Sleep