Intense late-night exercise interferes with sleep

Active lifestyle is considered to be the key to health, but evening workout can unexpectedly turn into problems with sleep. Researchers from Monash University in Australia analyzed data from nearly 15,000 people and found that physical activity before bedtime disrupts its duration and quality.

The study, published in Nature Communications, was the largest on this topic: more than four million nights of observation were collected over the course of a year. Participants wore a special WHOOP biometric bracelet that recorded sleep, heart rate and physical activity levels.

The scientists’ attention was focused on how late activity affects falling asleep, total amount of sleep, its depth, resting heart rate and heart rate variability – an indicator related to the autonomic nervous system and body recovery.

It turned out that the closer the workout was to bedtime and the higher its intensity, the worse a person slept. Those who exercised four hours before bedtime or later, fell asleep later, slept less and less deeply, and their body remained in tension even at night – the pulse was higher than usual, and the variability of heart rate decreased.

The authors clarify: we are not talking about a light warm-up or an evening walk, but serious exercise – like a soccer match, running, strength training or HIIT. Such activities raise your body temperature, breathing, heart rate and wakefulness level – all things that keep your body from relaxing and adjusting to sleep.

According to Dr. Josh Leota, one of the study’s authors, previous conclusions about the harmlessness of evening workouts were often based on experiments with small numbers of participants and without taking real-world conditions into account.

If you want to improve the quality of your sleep, experts advise you to complete your workouts at least four hours before bedtime. And if time is limited and you can only exercise in the evening, it’s best to opt for something gentle, such as calm swimming, yoga or slow jogging.

Dr. Elise Facer-Childs, co-author of the project, emphasizes: the results of the study are important not only for individuals, but also for shaping societal recommendations. With most adults struggling with sleep disturbances, the proper allocation of physical activity can be an important step to improving overall health.

Sport can indeed help you sleep better – but only if you get the timing and pace right.