Hitting the gym for a vigorous session in the evening could be significantly disrupting your sleep, according to new scientific research. Experts are urging fitness enthusiasts to reconsider the timing of their workouts to protect their nightly rest.
The Science of Sleep and Evening Exercise
Health professionals warn that intense physical activity close to bedtime has a direct and measurable impact on sleep patterns. Josh Leota, PhD, a sleep and circadian scientist at Monash University in Australia, explains that the intensity of a workout is a crucial factor. "The harder you work out, the more activated your body becomes and your nervous system is in a more alert, amped up state," he told Women’s Health.
He further clarified that while the body does recover, "the time it takes to settle back down is proportional to how hard the workout was." Dr Leota noted that lighter activity, such as a 30-minute jog one to two hours before bed, is unlikely to cause problems.
Research Reveals Significant Sleep Loss
Dr Leota contributed to a recent study published in the journal Nature Communications, which provides stark data on the issue. The research found that when people engaged in maximal exercise two hours before bedtime, instead of light exercise, they experienced notable sleep disruption.
The results showed participants fell asleep 36 minutes later than usual and slept for 22 minutes less overall. Consequently, the study recommends finishing intense workouts, like speed runs, at least four hours before going to sleep.
This finding is supported by a 2023 review in the journal Cureus, which analysed multiple studies on physical activity and sleep. The review confirmed a negative relationship between nighttime physical activity and sleep quality for both men and women. It specified that high-intensity interval training (HIIT) performed an hour before bedtime could be detrimental, and evening vigorous exercise sessions lasting more than 90 minutes are also linked to poor sleep.
Expert Recommendations for Optimal Timing
The consensus among sleep scientists is clear: for the best night's rest, schedule strenuous exercise earlier in the day. Dr. Andrew Colsky, a sleep science expert and founder of the National Sleep Center, advocates for morning workouts. "The reason for this is that when we wake up from a night of restful sleep, our sleep drive has been depleted and we are setting our circadian rhythm by getting good light exposure," he explained to Real Simple.
However, experts unanimously agree that some exercise is always better than none. Jingyi Qian, PhD, a sleep scientist at Mass General Brigham, offers pragmatic advice: "If you can exercise, do it. In general, physical activity is good for you and most people have too little rather than too much. If evening is the only time that people can find to do some exercise, I would recommend people do it."
Dr Leota also reiterated the overarching benefits of regular exercise, including improved mood and better sleep in the long term. The key takeaway is to be strategic: if your goal is peak physical performance and maximum recovery, align intense training with your body's natural rhythms by opting for a morning or afternoon session whenever possible.
