According to a 2016 study of nearly half a million Americans, almost a third of adults are not getting a healthy amount of sleep, proving the need for increased public awareness and education about the critical role sleep plays in our health and resilience. One of the most commonly recommended ways to increase sleep quality and duration is to get more exercise – but has this been proven? Does it always work, and if so, how?
There have been a great number of studies on the relationship between sleep and exercise, from large-scale questionnaires to detailed looks at specific parts of the population. The majority of them show that increasing the amount of exercise you’re getting during the daytime is likely to improve your sleep. However, some are more nuanced, suggesting that in certain conditions, exercise could actually undermine sleep quality.
How Exercise Can Improve Your Mood and Sleep
It is widely believed that exercise can help to increase slow-wave sleep, which is the deepest, most restorative part of sleep. What’s more, most studies looking at the relation between the two show that it can help to increase the length of sleep too, which is helpful for people who have trouble staying asleep or who wake earlier than they would like. This is thought to be the result of the additional energy expended during exercise.
As part of the process of falling asleep, our core body temperature drops, which is why it’s important to keep your bedroom reasonably cool. Exercise is thought to help this process, as our core body temperature rises during exercise, then drops afterward, which can trigger sleep. For this to work, you should exercise in the early evening, to allow time for your body temperature to drop again afterward.
As well as aiding in the mechanisms of sleep, exercise can also help to combat the causes of insomnia. Regular, moderate exercise can help lower stress and anxiety, two common causes of sleeplessness. In fact, depression and anxiety are less prevalent among people who exercise regularly and consistently.
Another study has found that regular exercise can help to improve oxygen intake and usage, helping to reduce the severity of sleep-disordered breathing and obstructive sleep apnea.
If you find that regular exercise helps you to sleep better, it’s possible to get into a very positive cycle whereby exercising improves your sleep, and in turn, better sleep improves your performance during workouts and your desire to exercise more. However, although this may work for many people, it might not be suitable for everyone who’s trying to get better sleep.
Can Exercise Make Your Sleep Worse?
Almost all the studies on the relationship between sleep and exercise show variability relating to the age, health, and lifestyles of the participants, as well as the type and intensity of exercise taken up.
Many of the findings seem to show that the older the participants, the more effective exercise is at improving sleep. However, that might be because younger people are more likely to have an established exercise routine, to be more active in their daily lives and careers, or to do more intense workouts.
The intensity of the workout seems to make a big difference, as many studies reported that medium-intensity exercise, like a brisk walk, is the key to promoting restful sleep. At the other end of the scale, high-intensity workouts, especially for athletes, have been shown to actually make sleep worse.
Linked to the intensity of the workout is the regularity: 30 minutes a day might be better than one weekly 3-hour session. It can take some time to see results with this method, however, and maybe worth tracking your sleep to spot improvements. Interestingly, a Finnish study found that the reason for the exercise was also important, as participants who exercised for leisure slept better than those who exercised as part of their job.
Similarly, the timing of the exercise could play a role. Some studies suggest that exercising outside during daylight hours could help to reset the circadian rhythm, while others show that also doing some gentle exercise, like yoga, before bed could help people to unwind and relax ready for sleep. Most studies agree, however, that it is best to avoid high-intensity workouts a few hours before bedtime.
How to Exercise for Better Mood and Sleep
- Establish a routine: The best way to help your circadian rhythm is to stick to a regular exercise routine, as well as regular bed and wake-up times.
- Little and often: In terms of improving sleep, exercising more frequently but in shorter bursts could be more effective.
- Time it right: Keep high-intensity workouts like running or lifting weights to the morning or early afternoon, and relaxing, low-intensity exercise for the evening.
- Keep track: Use a sleep tracker app or device to gauge your sleep quality, remembering to also track workouts and activity levels to see what works and what doesn’t.
- Maintain good sleep hygiene: Even if you’re getting regular exercise, the benefits could be undone by unhealthy sleep habits like too much screen time in the evenings or a disruptive sleep environment.