Do you feel you sleep better on the days you’ve burnt off 1000 calories during an intense workout?
But do you still sleep well if you have a heart-pumping session late in the evening, or only do gentle exercise?
Personally, I find that physical exercise usually helps in my lifelong battle with insomnia. I say ‘usually’ because there are times when I suspect it has the opposite effect – when I’m too hot to sleep or because I’ve overtrained.
Why the link between exercise and sleep matters to me
The relationship between sleep and exercise is is a topic I care deeply about. I’m a keen climber and swimmer, and also train hard in the gym to compliment both activities.
I need adequate rest and sleep both to recover and to improve my future performance. And I also need to not have insomnia so I can function as a normal human being outside of my strict exercise regime.
In this article, I’m going to look at what researchers and sleep experts say about exercising your way to better sleep. And specifically, address three key questions that interest me:
- Can exercise really help you sleep?
- Are some types of exercise better than others if you want to improve your sleep?
- Does it matter what time of the day you do exercise?
National Sleep Foundation Poll shows how well exercisers and non-exercisers feel they sleep
Back in 2013, the National Sleep Foundation (NSF) conducted a fascinating poll of 1000 adults aged between 23 and 60.
The poll entailed a large number of questions, such as how much exercise they did, how long they slept for, and how well they felt they slept.
The results showed that those who did vigorous, moderate and light exercise were much more likely to say “I had a good night’s sleep” on all or nearly all work nights (67%-56%). But only 39% of those who did no exercise reported sleeping well.
And in the previous two weeks, 76%-83% of exercisers reported fairly good or very good sleep compared to just 56% of non-exercisers.
So the poll provides an initial answer to my first question: exercise does appear to be good for sleep.
Is vigorous exercise best for sleep?
The poll also suggests an answer to my second question: what type of exercise most helps sleep?
The answer, at least as reported by people, looks like vigorous exercise, such as running and cycling. Not only were they almost twice as likely as non-exercisers to report good sleep, but more than two thirds of this group said they never or rarely had insomnia symptoms.
And even compared to moderate and light exercisers, the results were better. For example, 40% of the vigorous exercisers rarely or never woke during the night, compared to 31% of moderate and also 31% of light exercisers.
Exercise improves sleep quality
Interestingly, despite the big differences in self-reported sleep quality, the total time wasn’t significantly different between exercisers and non-exercisers (6 hours and 51 minutes on average).
So the positive effect appeared to be more about the quality of sleep than the total amount.
Research studies showing exercise improves sleep
In 2017, a team of researchers in the USA published a research review of 34 studies on exercise and sleep that had been conducted between 2013 and 2017. One of their main aims was to find definitive conclusions on the impact of exercise on sleep.
They found that 29 studies showed sleep improved sleep quality or duration. 4 found no difference and 1 showed a negative effect.
What was interesting is that they discovered differences in success rates based on the age of participants in the studies.
The team wrote that:
Mixed findings were reported for children, adolescents, and young adults. Interventions conducted with middle-aged and elderly adults reported more robust results. In these cases, exercise promoted increased sleep efficiency and duration regardless of the mode and intensity of activity, especially in populations suffering from disease.
Overall though, their review provides further backing to the notion that regular exercise might have a beneficial effect on your sleep.
Does exercise late in the day worsen sleep?
Going back to what I said at the start of this article, I often find that a late gym session makes falling asleep trickier.
For example, if I hit the gym at 8.30 p.m., and then go to bed at 10 p.m., I can go from recently cooled down back to sweating again in 60 seconds.
And in the hot summer months, if I don’t have any cooling tech in my bedroom, I know I’ll lie there for a couple of hours until my temperature drops back down and I can sleep.
But is this just me? Or do surveys and sleep research find the same problem with other people?
The authors of the NSF poll had this to say:
…the conclusion can be drawn that exercise, or physical activity in general, is generally good for sleep, regardless of the time of day the activity is performed.
In short, they compared people who exercised in the 4 hours before bedtime with those whose exercise was done more than 4 hours before bed. And they found no significant difference.
Here are some of the key results:
People who reported good overall sleep quality
- 76% of people who did moderate or vigorous exercise within the 4 hours before bedtime.
- 81% who exercised more than 4 hours before bedtime.
Sleep improves on exercise days
- 55% who exercised within the 4 hours before bedtime
- 54% who exercised more than 4 hours before bedtime
Total sleep time improves on exercise days
- 33% who exercised within the 4 hours before bedtime
- 29% who exercised more than 4 hours before bedtime
Note that all the people questioned reported improvements in quality and length of sleep on exercise days, regardless of when they undertook the exercise.
A number of articles in the press picked up on this NSF poll and suggested that any exercise before bedtime is okay for getting a good night’s sleep.
It could be argued though that the 4 hour band is too broad. In my experience, I can cool down in 3-4 hours and sleep ok, but going to bed an hour after staggering back from the gym is a recipe for turning my bed into a temporary sauna.
The NSF poll is certainly interesting, but the fact that the results are based on self-reporting of sleep quality leaves room to question some of the finer details. So I turned to some other research to look at the timing of the exercise issue from another angle.
In 2013, researchers at Hokusho University in Japan conducted a study involving 12 healthy males. On different days, they did no exercise, moderate or high exercise shortly before going to bed.
They found that on average vigorous exercise resulted in the participants taking an average of 14 minutes longer to fall asleep, compared to non-exercise days.
The researchers reported:
These results indicate that pre-sleep vigorous exercise, which causes a large physiologic excitement at bedtime, might disrupt the onset of sleep.
Interestingly, the National Sleep Foundation, which conducted the 2013 poll, now don’t recommend late exercise on their website sleep.org, saying:
..most people should avoid strenuous workouts in the late evening or right before bed (that means no 9:00pm CrossFit!). The boost in body temperature that comes with cardio workouts, along with their stimulating nature, might interfere with falling asleep.
But they also say that some people might be fine with this kind of late exercise:
…it’s important to note that nighttime workouts don’t have the same affect on every single person, so if they’re not interfering with your sleep, then there’s no need to switch your routine.
So it seems that although any exercise is better than no exercise when it comes to sleep, it’s probably sensible to get your timing right and give both your body and mind sufficient time to cool down before trying to sleep.
Whether you personally need 1, 2, 3, 4 or even more hours for that is probably down to a complex set of hidden factors, so you might need some trial and error to work out what your body thrives on.
What about less strenuous exercise?
Some forms of less vigorous exercise may well be helpful, even immediately before bed. For example, yoga has been shown in research to improve sleep, and tai-chi or stretching sessions are often recommended as positive activities to do before going to bed.
This is because they can help decrease arousal, clear the mind and relax. Not so much that they tire you out in the way that exercise does.
Having said that, the level of appropriate activity is arguably relative to the individual. Researchers have shown that daily yoga can improve both the sleep quality and quality of life in the elderly, for example.
Exercise is generally good for you in many ways, that much is clear. And there is mounting evidence that exercise can help some people sleep better. It’s important to note that sleep researchers, such as those in the USA study, point out that much still remains to be understood.
But if it’s true that exercise leads to better sleep, then doing it at the best time of the day so it doesn’t have the opposite effect seems to be the current suggestion from sleep experts.
If you still want the flexibility to exercise right up until bedtime, then perhaps you could experiment with the best timings.
You could try spending a week doing your chosen exercise a few hours before bed. Then the next week, push it a little closer to bedtime until you find the point where it starts to disrupt your sleep – assuming it does at some point!
You should be able to decide for yourself if you can exercise before bed or not, or if you need to leave a length gap between getting your breath back and getting into bed.
If you have an activity tracker which also measures sleep, then you could use that to help you decide if your sleep is improving or being disrupted by exercising at a different time.
If you have no option but to exercise right before bedtime, then there are some measures you might want to try to see if they help you:
- Take time at the end for a cool down exercise period, letting your breathing and heart rate gradually return to normal.
- Take a short cool or even cold shower to help get your body temperature down.
- Make sure you rehydrate.
- Do relaxation exercises in bed, which can help bring your arousal levels down.
- Keep your bedroom cool (have a look at these cooling tips for ideas).
Does exercise have an effect on the quality of your sleep? Let me know in the comments below!