How much you need to exercise for better sleep, according to experts

Ever notice how some workouts put you to sleep while others make you feel like someone switched out your vitamins for caffeine pills? You’re not going crazy. Exercise can significantly impact your sleep—for better or for worse—depending on how, and when, you work out.

Unfortunately, the exercise-sleep relationship is not as straightforward as the internet’s sleepmaxxers might lead you to believe. While research has unlocked some valuable insights that you can start putting into practice later tonight, there’s still a lot we don’t know. "Part of what's vexing about this is we don't have the mechanism totally locked down,” says James Wyatt, PhD, clinical sleep disorder specialist at Rush University System for Health in Chicago.

"It's also important to caveat that, while the data is enormously helpful, there's so much intra-individual variability,” says Kristen Holmes, PhD, global head of human performance and principal scientist at Whoop. At the end of the day (literally), sleep is a complex chemical equation that differs to various degrees from person to person.

But back to those valuable insights. From morning HIIT workouts that reset your circadian rhythm to an evening workout to hack your body’s natural cooling system, here are some of the best ways to use exercise to fall asleep faster, according to experts.

Working out in general won’t make you fall asleep faster

Exercise can certainly reduce the time it takes to fall asleep, but not for the reason that many wellness influencers would have you think—that is, by spurring your body’s natural production of adenosine, a sleep-inducing compound that is also a byproduct of exercise.

Your body’s cells rely on a molecule called adenosine triphosphate, or ATP, for energy. It’s a universal fuel source that powers everything from muscle contractions to brain function to simply existing. As ATP is utilized, it produces a compound called adenosine. Adenosine is not a waste product. In fact, it is highly valuable. “In muscle, adenosine helps to reduce inflammation and limit damage during periods of metabolic stress,” says Dr. Holmes. Meanwhile, in the brain, adenosine accumulates throughout the day, gradually making you feel sleepier. “In sleep science, this is called ‘sleep pressure,’” says Dr. Holmes.

So it seems perfectly plausible that the key to falling asleep faster would simply be to exercise. More exertion equals more adenosine and therefore greater sleep pressure. A 2007 study published in the journal Neuroscience actually found that when rats engaged in intense exercise, the levels of adenosine in their brains increased significantly.

But that’s not how it works in humans. "Adenosine can do an awful lot of different things in the brain and in the body, but we have to separate these,” says Dr. Wyatt. This is because adenosine doesn’t cross the blood-brain barrier—the wrapping around your brain that selectively allows certain chemicals in and not others. “If you build up adenosine in your body as a byproduct of exercising, that will not influence what happens in your brain,” Dr. Wyatt says. “That adenosine doesn't make it into the brain.”

Make no mistake, adenosine is still crucial for sleep in humans. "Adenosine on its own is one of the major chemicals that helps us fall asleep at night and get deep sleep for the first couple of hours,” Dr. Wyatt says. But only adenosine that is created in the brain will ultimately contribute to increasing sleep pressure.

The timing of your workout may be more important than the duration

In terms of how hard or how long you need to work out in order to fall asleep faster, experts aren’t entirely sure of this, or if it even matters all that much. "We don't have a lot of great data on the intensity of exercise that's needed,” says Dr. Wyatt. The main reason for this, it seems, is that exercise’s ability to improve sleep is likely not a direct function of intensity—or any single factor, for that matter—but rather a combination of variables, including timing. For example, working out at a high intensity could be helpful in the morning, but detrimental later on in the day.

"One way that exercise could indirectly influence sleep is that it strengthens your circadian rhythm—that 24-hour daily rhythm of alertness during the day and sleepiness at night,” says Dr. Wyatt. In other words, working out earlier in the day can help your body understand that it’s daytime, and that in a couple of hours it will be time to sleep. But slow cardio isn’t going to cut it. “In animals, if you look at a rat or a mouse, the time during the day when you give them access to exercise dramatically shifts their circadian rhythm,” Dr. Wyatt says. “But in humans, exercise is a very weak signal for aligning ourselves to the 24-hour day, so it has to be an awful lot of exercise to have a notable effect.” (We recommend giving this HIIT workout a try.)

As for going all out in the evening, in a 2025 study published in the journal Nature Communications, researchers observed that high-strain workouts done within four hours of bedtime had a range of detrimental effects on sleep. In the study, data from nearly 15,000 Whoop members across more than four million nights revealed that an intense evening workout can delay sleep onset, reduce total sleep duration, and degrade overall sleep quality. “Basically, what we found is that intense exercise ending within four hours of going to bed was associated with these changes in sleep,” says Dr. Holmes. “When you're exercising at a high intensity, you're releasing adrenaline, cortisol, and epinephrine, so it's going to take time afterwards for that to dissipate.”

How to work out to fall asleep faster

According to Dr. Wyatt and Dr. Holmes, there are basically two types of workouts that may potentially help you fall asleep faster. The first one, as mentioned, is a high-intensity session during the day—the earlier the better—to help click your circadian rhythm into sync with the day. Ideally, you’ll want to also include some natural sunlight in the equation or, better yet, train outdoors. “From a circadian perspective, you want to create as much contrast between the day and the night as possible,” says Dr. Holmes.

The other option is an evening workout—albeit a relatively light one. According to the Whoop study data, when people engaged in a low-intensity evening workout, they experienced better sleep quality than those who didn’t exercise at all—and they only needed one hour of buffer time between training and going to bed.

The sleep-inducing power of a low-intensity evening workout has nothing to do with your circadian rhythm and everything to do with body temperature. As you approach bedtime, your body is naturally configured to move heat away from its core—a process that contributes to feelings of sleepiness. Exercise, of course, does the opposite and raises your core temperature, but it also makes your body work harder to lower it. According to John Hopkins Medicine, core temperature starts to fall about 30–90 minutes after exercising. Timing your workout to end 1–2 hours before bedtime—which, according to Dr. Wyatt, also happens to be right around the time your brain starts releasing melatonin—effectively layers that post-workout temperature drop on top of your body’s natural cooling process, creating the perfect sleep storm. “Exercise ramps up body temperature even more, and therefore it has an even steeper drop,” Dr. Wyatt says. “The steepness of that drop in body temperature is what might be associated with the ability to fall asleep faster.”

“The general guidance is: Evening exercise can help sleep, too close to bed is bad, and too far away from bedtime may be ineffective. But again, there are those individual differences,” Dr. Wyatt says. “This is why it's challenging. It's not going to be just a single recipe that says, ‘Okay, do this one thing and sleep suddenly gets better.’ You have to find the combination that works for you.”