MONTREAL, Quebec — Exercise may not be so great for your sleep — depending on when you’re working out. Although exercise is typically beneficial and helps people get a good night’s rest, a new study finds breaking a good sweat too close to your bedtime can actually keep you up later and cause you to sleep less.
Researchers from Concordia University looked at the relationship between exercise and sleep quality across 15 published studies. The results show, although everyone’s sleep cycles are a little different, a heavy workout within two hours of your normal bedtime can disrupt how much rapid-eye-movement (REM) sleep you get that night.
“When we reviewed the literature on this work, we found that there were a lot of mixed results,” says Melodee Mograss, a cognitive neuropsychologist and researcher at the PERFORM Sleep Lab, in a university release. “Some depended on the time of exercise, others on the fitness level of a study’s participants, or even the type of exercise.”
Timing is everything when exercising before bed
Study authors examined how high-intensity exercise affects sleep that night and what factors tied to working out influence good or bad sleep. The 15 studies looked at the timing of exercise, including early and late evening workouts, and the time in between that workout and when participants went to bed. Researchers broke these intervals down into three groups: less than two hours before bed, around two hours before bed, and two to four hours before bed.
The team also accounted for other factors such as each person’s fitness level, whether they have a physically active or sedentary lifestyle, the intensity of these workouts, and the length of their exercise sessions.
“Overall, our analysis showed that when exercise ended two hours before bedtime, there were sleep benefits, including the promotion of sleep onset and increased sleep duration,” the study’s lead author says Emmanuel Frimpong.
“On the other hand, when exercise ended less than two hours before bedtime, sleep was negatively impacted. It took longer for participants to fall asleep and sleep duration decreased.”
Moreover, the study finds high-intensity exercise in the early evening promotes sleep onset and helps people sleep longer. This is especially true for people who have a sedentary lifestyle. Additionally, high-intensity exercise for only 30 to 60 minutes improves sleep as well.
For bikers, there’s even more good news. The study finds cycling exercises benefit sleep quality the most.
Intense workouts affect your dreams?
Along with exercising too close to bedtime, researchers also found that high-intensity exercise before sleep also lowers the amount of rapid-eye-movement (REM) sleep someone gets. This stage of sleep has connections to both dreaming and overall health. Previous studies show that getting less REM sleep negatively impacts cognitive performance.
“Based on our review, for healthy, young and middle-aged adults with no history of sleep disorders, evening exercises should be performed in the early evening if possible,” Frimpong says.
“Individuals should also keep to a consistent exercise schedule, as exercising at different times of the evening could cause sleep disturbances. Individuals should also consider whether they are morning people or evening people. High intensity exercise performed late in the evening can result in sleep disturbance for morning-type people,” the study author concludes.
“And lastly, sleep hygiene strategies should also be carried out, such as taking a shower between the cessation of exercise and bedtime and avoiding eating heavy meals or drinking a lot of water before going to bed.”
The findings appear in the journal Sleep Medicine Reviews.