Does Exercise Affect How Well You Sleep?

Although it makes a certain amount of sense that higher physical activity leads to more sleep, numerous studies are showing that there are a ton of other factors to consider, particularly the effect that sleep might have on exercise rather than the other way around.
03/10/2016 04:10 pm ET Updated Dec 06, 2017

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Anybody who has spent a day engaged in a ton of exercise knows how it feels to crash into bed that night. Whether you had an extra-hard gym session or you spent hours working a physical job, by the end of the day your entire body is exhausted and ready for some well-deserved sleep. But what happens if you end up simply lying in bed, staring at the ceiling? Shouldn't a ton of exercise make you fall asleep quickly? The answer to that question is a lot more complicated than it seems. Although it makes a certain amount of sense that higher physical activity leads to more sleep, numerous studies are showing that there are a ton of other factors to consider, particularly the effect that sleep might have on exercise rather than the other way around.

The occasional bout of exercise may not be a magic pill that leads to the best sleep possible, but there are still plenty of benefits to be reaped from regular workouts and getting proper rest. Let's take a look at how exercise affects sleep -- and vice versa -- as well as why a few casual workouts here and there might not be a miracle cure for sleepless nights.

Consistent Exercise Means Better Sleep -- Eventually

The formula seems simple: exhaust your body to the point that it craves deep, restful sleep. You may have even read articles that recommend hitting the gym before bed as the best way to wake up refreshed the next day. By all accounts, it makes sense, yet studies have been done on this hypothesis and found that it doesn't quite hold up -- at least, not immediately.

An article from Psychology Today looks at a 2013 study by the Journal of Clinical Sleep Medicine that determines the obvious -- that regular exercise does contribute to better sleep -- but with an important clause: that the improved sleep might take place down the road. "In particular, the study suggests that exercise may not have an immediate impact on sleep, but in fact may take several weeks or months to significantly change sleep," says Psychology Today, before continuing to note that the study's focus group "experienced no significant improvements" in their sleep after two months into the 16-week study period. But after the 16 weeks were up, their sleep quality had greatly improved: "Exercising subjects in the 16-week study eventually wound up sleeping as much as an additional 1.25 hours per night more than their non-exercising counterparts."

However, there's yet another important factor to consider in this study: that no one who took part had regular sleep problems. In a piece for the New York Times, Dr. Kelly Glazer Baron, a clinical psychologist and sleep researcher at the Feinberg School of Medicine at Northwestern University, examines that same study's findings and remarks on the participants: "For them, exercise and sleep seem to have a relatively uncomplicated relationship. You work out, fatigue your body and mind, and sleep more soundly that night. But people with insomnia and other sleep disturbances tend to be 'neurologically different' ... They have what we characterize as a hyper-arousal of the stress system."

Dr. Baron also brings up the fact that exercise is a physical stressor, and can even aggravate the stress system to the point that it interrupts sleep -- which could explain why some of us can't seem to fall asleep even if our bodies are exhausted. Yet once the body and brain become used to a consistent exercise routine, Dr. Baron notes that the stress response is "dialed down" enough to allow for quicker and deeper sleep.

Sure enough, an earlier study done on sleep and exercise in adults with insomnia found that when participants engaged in moderate aerobic exercise for 30 minutes three to four times per week, after 16 weeks they had "improved sleep significantly and across several measures of sleep, including sleep duration and sleep quality, as well as daytime sleepiness," says Psychology Today. These insomniac participants also reported that prolonged exercise and improved sleep contributed to better moods and quality of life.

The Exercise vs. Sleep Effect

The need for a prolonged exercise regimen wasn't the only thing the 2013 study (as well as the study before it) discovered -- it also made a connection between a poor night's sleep and a bad workout the next day. The New York Times article also refers to this portion of the study, noting some additional condemning details from the group: "They also rarely reported sleeping better on those nights when they had had an exercise session. And perhaps most telling, they almost always exercised for a shorter amount of time on the days after a poor night's sleep. In other words, sleeping badly tended to shorten the next day's workout, while a full-length exercise session did not, in most cases, produce more and better sleep that night."

It can be easy to look at these findings and determine that it's a lose-lose situation: Exercising doesn't provide more or better sleep, and sleeping poorly leads to a poor workout anyway. But as with any routine, it takes a little bit longer than a couple weeks to reap the benefits. The Psychology Today piece urges sleepless individuals to look at it like weight loss: It doesn't happen right away, but there are definitely small improvements happening under the surface.

"First, this study did confirm that exercise can have a dramatic effect on sleep," the article reassures anyone currently dubious about exercise helping their sleep patterns. "Exercising subjects in the 16-week study eventually wound up sleeping as much as an additional 1.25 hours per night more than their non-exercising counterparts. If you're not a regular exerciser and you're looking for a way to improve your sleep, starting a routine of moderate physical activity is a great strategy."

In other words: The better sleep you get, the better workouts you'll have, and those better workouts will eventually help to promote a deeper sleep. It may seem discouraging at first, but if you keep up with a moderate exercise regimen, eventually you'll set off a positive chain reaction that leads to improvements in both areas. (If you have legitimate clinical sleep problems, as always, it's best to seek the advice of a medical professional before choosing exercise as your go-to sleep cure.)

Conclusion

If you're having difficulty sleeping and considering hitting the gym a couple times a week to help catch some Zs, just keep in mind the findings of the study above: namely, that you need to make exercise a more frequent activity for a prolonged period of time before you begin to see tangible results. Although the effect might not be immediate, in the long run, maintaining a moderate exercise routine can go a long way in helping improve quality of sleep and quality of life.

Have you ever upped your exercise in order to get better sleep? How did it work out for you?