In terms of the best exercise for sleep, Harris says any sort of workout is good. As long as you’re moving your body in some way, you’re in good shape. Specifically, though, she recommends doing any sort of cardio four to six hours before bed, as this type of exercise raises your heart rate and body temperature.
“If you want to help your ability to fall asleep and stay asleep, four to six hours before bed is great,” Harris notes. “It’s warming your internal body temperature up, which is what you want to have happen, and then a few hours later, you start cooling down. And that cooling down process about one to two hours before sleep is what helps your brain release melatonin, and it helps induce sleepiness.” Your core body temperature naturally decreases during sleep, after all.
On the flip-side: “If you exercise within three hours of bed, you’re actually warming yourself up and making yourself too warm to fall asleep,” Harris says. “You might feel relaxed mentally and physically, but your internal body temperature is too high that it actually makes it hard to sleep.” In fact, one 2019 study in the journal Sports Medicine found that those who did vigorous exercise less than one hour before bed took longer to fall asleep and had poorer sleep quality.
So if you can time your workouts four to six hours before bed, Harris says that’s ideal. Now, if you’re partial to morning workouts, which does not fall within that four to six hour window, that’s fine, too. “I work out in the morning every day,” says Harris. “It’s great, but I don’t expect it to help or hurt my sleep.”