Can’t sleep? You’re not alone. Around 1/3 of the population struggle with insomnia for short periods of time while 10% have chronic problems sleeping, meaning they have a hard time falling asleep night after night. These folks toss and turn, count sheep, or listen to soothing sounds in an attempt to quiet their racing mind, often, to no avail. While there’s no cure for insomnia that works for everyone, lifestyle changes can make a difference. But, it may require more than just giving up caffeine, a stimulant that makes it harder to unwind if you drink it too late in the day.
What about exercise? We know that exercise has lots of health benefits, but do those benefits extend to improving sleep? Possibly. But, as a study shows, there’s a caveat. You won’t reap the benefits right away – but you might down the road.
Exercise, Sleep Quality, and Insomnia
In a study published in the Journal of Clinical Sleep Medicine, researchers looked at activity and sleep logs from 11 women who were late middle-aged and older. All of the participants reported problems with insomnia. They then analyzed their sleep and activity records for a full 16 weeks. What they found was aerobic activity helped the women sleep better but the benefits didn’t show up until almost 4 months after they began exercising. Yet, after several months, the women reported enough improvement that they were sleeping, on average, an additional 45 minutes each night.
So, if you’re exercising in hopes of sleeping better, patience is in order. You probably won’t see the results right away. Too often, we want quick solutions to problems, but this study suggests you won’t experience sleep improvements right away.
Now that we know that exercise can help you get a better night’s sleep if you’re patient and stick with it, what about when you exercise at night? People commonly think that you shouldn’t exercise at night as exercise is activating and energizing. If you’re consumed with energy, it could make it harder to drift off to sleep. In fact, some people work out because it gives them more energy.
However, some people seem to be more sensitive to the activating effects of exercise than others. In other words, evening workouts can cause some, but not all, people to have problems falling asleep. This isn’t surprising since exercise stimulates the release of hormones, like adrenaline, that speed up your heart rate and make you more alert and aware. That’s partially why you feel so invigorated after a heart-pounding workout.
Plus, exercise raises your core body temperature. That isn’t necessarily a negative. Some studies show that a rise in body temperature before sleep can actually help you sleep better, especially if the rise in body temperature is followed by a drop.
Whether you struggle to fall asleep after a workout may depend on the intensity with which you exercised. Did you do a light circuit workout or a vigorous high-intensity interval routine? Intense workouts are more likely to interfere with sleep than taking a leisurely walk or doing other lower intensity forms of exercise, as vigorous exercise triggers a greater release of hormones and chemicals that increase heart rate and make you more alert.
So, if you exercise after dinner and are prone towards insomnia, dialing back the intensity might be appropriate. Save the high-intensity workouts for early in the day when you need to be awake and alert. In fact, the National Sleep Foundation, recommends exercising at least three hours before bedtime. This should give you enough time to cool down and calm down before it’s time to turn in.
Ultimately, a morning workout may be more beneficial anyway for helping you get quality sleep. A study that involved 173 middle-aged and older women with sleep problems were assigned to either aerobic exercise or stretching at one of two times – in the morning at around 10:30 A.M. or in the evening at around 6 p.m.
What the study showed was that aerobic exercise was better than stretching for improving sleep although both had some impact. Exercising at least 3 hours per week was associated with the greatest improvements in sleep. Working out less than 3 hours weekly had less of a benefit on sleep quality. Finally, participants who exercised in the morning enjoyed greater improvements in sleep than those who worked out in the evening.
How might exercise make it easier to slumber? Exercise causes a rise in body temperature and the drop in core temperature that occurs after a workout may make it easier to drift off to sleep. In fact, studies show that a warm bath an hour or two before bedtime helps with sleep. According to this research, a rise in body temperature followed by the fall that follows signals our natural circadian rhythms to prepare our bodies for sleep. In response, to the rise and fall in body temperature, our heart rate and breathing slows and our body goes into sleep mode.
Exercise also helps reduce stress and relieve anxiety. Some people have problems sleeping because they lie awake worrying and their brain won’t shut down. Exercise may help relieve stress and ease brain overactivity. You’ve probably experienced the anti-stress effects of exercise yourself.
The Bottom Line
Aerobic exercise may improve the quality of your sleep if you’re consistent with it and you exercise at least 3 hours weekly. You’ll probably need to stick with it for 3 or 4 months before you notice a significant improvement. If you do evening workouts, try to exercise at least 3 hours before bedtime. Even better, work out in the morning, especially if you do high-intensity workouts – and regardless of when you exercise, consider taking a warm bath an hour before bedtime!
References:
Sleep Education. “Insomnia Awareness Day facts and stats”
WebMD.com. “Can Exercising at Night Hurt Your Sleep?”
JAMA 1997; 227: 32-37.
Sleep Foundation. “How Does Exercise Help Those with Insomnia?”
WebMD. “Morning Exercise May Help You Sleep”
Rthm.io. “The Science of How Warm Baths Promote Sleep”
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