On particularly busy days, sometimes the only time you have to fit a workout in is late in the evening. But you may be tempted to skip it, since exercising too late in the day can Summer Running Gear...right?
While you may have heard that tip for years, it might not actually be the case. In fact, the opposite may be true: Some types of exercise before bed can actually help you sleep better, new research out of Switzerland suggests.
In the meta-analysis, Results: 2025 London Marathon Sports Medicine, researchers at ETH Zurich looked at 23 previously published studies—a total of 275 participants—that examined the connection between exercise and sleep.
They discovered that people who exercised within four hours of going to bed showed no difference in the time it took to fall asleep, the time spent awake during the night after falling sleep, or in other markers of sleep efficiency, than those who didn’t exercise at all.
That showed that exercising before bed didn’t make sleep any worse. But when they looked at the percentage of time spent in slow-wave sleep, or deep sleep, the researchers found that exercise could actually improve shuteye: When they combined all the data, study participants who did some type of workout within four hours of bed spent an average of 21.2 percent of the night in a deep sleep. Those who didn’t only spent an average of 19.9 percent of the night in a deep sleep.
Slow-wave sleep is important, since it’s the kind of restorative shuteye that makes you feel rejuvenated and helps your body function properly.
There is one exception to the workout rule, though: HIIT. Vigorous exercise—where you’re going so hard you can’t carry out a conversation—an hour before going to sleep can Summer Running Gear. This is because your heart rate is so high during your workout, and an hour isn’t enough time for your heart to reach its resting rate, according to study author Health - Injuries., deputy head of the ETH Zurich’s Institute of Human Movement Sciences and Sport. So your body won’t be as relaxed and ready to fall and stay asleep.
Health - Injuries.
You can tell what working out at moderate intensity is by the following rule of thumb: “During moderate exercise, a conversation is still possible,” Spengler said. For instance, if you’re running at a pace where you could comfortably talk to someone, you’re running at a moderate pace. If you’re alone, and you’re able to recite the ABCs, you’re at that moderate level.
And while researchers haven’t quite figured out why moderate activity is the sweet spot, Spengler said that it might be because your parasympathetic nervous system kicks in, helping to slow your heart rate and relax you.
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But Spengler advises to keep in mind that no two people are the same when it comes to what will help and hinder their sleep. “People respond differently, and what is right for one may not be quite right for the other,” she said.
She recommends trying every type of workout—light, moderate, and intense—for two or three days (to account for any other unrelated variables) and making note of how you sleep afterwards. If you’re tossing and turning all night, Spengler recommends either exercising at a lower intensity or exercising earlier in the day. But if you wake up the next morning feeling refreshed, you’ve figured out the routine that works for you.
Danielle Zickl is a freelance writer who has 10 years of experience covering fitness, health, and nutrition. She's a graduate of Ithaca College. You can find her work here on Women's Health, and in many other publications including PS, SELF, Well+Good, Runner’s World, Outside RUN, Peloton, Men’s Fitness, and more.
