Exercise and sleep have a reciprocal effect; in other words, more of one typically leads to more of the other. For example, sleeping well gives us more energy, self-control, and a greater capacity for endurance exercise.
Being physically active helps to regulate all three main systems influencing your sleep.
Your circadian rhythms
Movement signals to our internal clocks that it’s daytime and time to be alert. Being physically active early in the day can help align our internal rhythms with the sun’s light-dark cycle and help us feel naturally sleepy at nightfall. However, late-night physical activity can delay the clock, so it’s recommended to stop intensive exercise at least an hour before bed.
Sleep pressure
The short-term effects of exercise include releasing adrenaline and endorphins, which make us more alert, so it can be a great way to stay awake. However, when we expend energy, we release adenosine, a signalling molecule that makes us drowsy. Once the activity ends, the adenosine build-up will increase our pressure to sleep and make it easier to fall asleep and stay asleep.
Stress system
While exercise behaves as a ‘stressor’ which activates the body, our stress hormones, blood pressure and heart rate all decrease after exercise. Exercise seems to make us more adaptable at switching off the stress response, leading to lower anxiety and physical tension levels. Exercise increases the amount of deep, slow-wave sleep, which is very physically restorative.
Exercise also strengthens our immune system, helps regulate appetite and blood sugar and improves emotional resilience. This is in addition to making us stronger and fitter.
Regular physical activity can reduce the risk of type 2 diabetes by up to 40%, depression by up to 30%, and colon and breast cancers by up to 20%.
It’s not clear from the research exactly how much exercise or how long we need to do to sleep better. It is likely to depend partly on age, baseline fitness levels, and the type of exercise we enjoy most. If you find exercise painful or unpleasant, you’re much less likely to repeat it, and it will probably have the reverse effect on your stress levels.
Several studies suggest that cardiorespiratory fitness is correlated with better sleep, suggesting that regular moderate to vigorous exercise – which gets the heart rate going – is an important factor.
Studies have found that this can be achieved in a variety of ways. For example, the following ‘recipes’ improved sleep in research studies.
- 30 min moderate intensity cycling three times a week.
- 30 min walking, callisthenics or dancing daily.
- 60 min moderate intensity running three days a week
A recent review of physical activity interventions in older adults found that the most reliable effects on sleep were for programmes which involved moderate-intensity exercise (where you’re still able to talk) at least three times a week for three to six months (Vanderlinden 2020).
However, one study on older women positively found that a single session of 54 minutes of moderate-intensity activity (on a treadmill) improved sleep quality the same evening.
Suppose, for any reason, you cannot engage in heart-pumping cardiovascular exercise. In that case, the good news is that there can also be benefits with lower intensity training – but it may take time.
Some studies have found that ‘mind-body’ exercises such as yoga and Tai Chi can positively affect sleep when practised regularly, several times a week.
A Brazilian study recruited adults aged 30 to 55 with chronic insomnia who didn’t exercise regularly. They completed a four-month programme which involved either 60 minutes of stretching or 60 minutes of weight training, three times a week.
At the end of the four-month programme, both groups significantly improved their sleep quality compared with a control group that didn’t exercise.
The UK physical activity guidelines recommend that adults engage in at least 150 minutes of moderate-intensity exercise per week or at least 75 minutes of vigorous-intensity exercise per week (breathing fast and difficulty talking), or a combination of both.
To keep muscles, bones and joints strong, it is also recommended to build strength at least two days a week by doing resistance training at the gym or yoga.
These recommendations have been created to help support better mood and health and are likely to benefit sleep. Even if you don’t have time to do 30 minutes or 60 minutes at a time, a short walk could still make a difference to your mood and stress levels on a day when you’re busy.
To supersize the beneficial effects of exercise on sleep, do it outside, exposure to natural daylight will help to sync your body clocks with the light-dark cycle of the sun. The most important thing to remember with exercise is that every little helps.
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- Regular physical activity is one of the best ways to improve the depth and timing of your sleep.
- It helps to synchronise your internal body clocks, setting you up for a good night’s sleep, especially when you exercise in the morning.
- It can help you to build sleep pressure so that you fall asleep faster.
- It reduces stress hormones and helps to tackle anxious thoughts so that you stay in a deeper sleep for longer.
Aim for 30–60 minutes of moderate-intensity exercise three times a week to improve your sleep quality, but remember that even one day could make a positive difference.
