The Impact of Exercise on Sleep

There is no doubt sleep plays a vital role in your overall health and wellbeing. When you aren’t getting enough good quality sleep it can impact your short- and long-term health. As we discuss regularly, there are many ways to improve the quality of sleep and in this blog we’re looking at the impact of exercise.

The benefits of exercise

It’s clear that exercise offers many benefits, from health and mood to sleep and stress.

Lifts mood

No matter how much you dread walking into the gym, there’s no denying that instant mood boost when you finish a workout! Exercising really can make you happier.

Reduces stress

When you exercise you’re pumping up your endorphins which can directly help to reduce stress. These “feel-good” neurotransmitters can make you feel happier, less stressed and more energetic.

Boosts energy

Both low- and high-intensity workouts have been proven to boost energy, so even when you feel you have no energy for a workout, you’ll actually reduce that sluggish feeling once you’ve exercised.

Improves health and fitness

This is a no-brainer: aerobic exercise (think workouts that make you huff and puff) keeps your heart and lungs strong. It can also improve your immune system, lower your blood pressure, and reduce the risk of type 2 diabetes.

Resistance (weight-based) training keeps lean muscles strong and improves bone density.

Time and time again fitness has been linked to a long life. Studies have shown fitness is the key, and it’s more important than body shape and even more important than other risk factors such as smoking.

Strengthens memory

Whether you’re terrible with names or suddenly can’t remember the reason you needed to visit a colleague’s office, memory lapses can be frustrating. Aerobic exercise has been found to boost the size of the hippocampus which is the part of the brain responsible for memory and learning.

Improves sleep

By reducing stress and tiring you out, exercise can improve sleep (as well as the quality of sleep).

In the long term, aerobic exercise can also improve sleeping disorders like sleep apnea.

Further, a 2005 study of men and women aged between 18 and 35 found that:


  • 150 minutes of moderate to vigorous exercise per week resulted in a 65% improvement in quality of sleep
  • Participants who were more active were 68% less likely to have leg cramps while sleeping
  • Those who were more active fell asleep quicker



Brad Cardinal, one of the study’s authors, recognises exercise as a “non-pharmaceutical alternative to improve sleep”.

The importance of sleep for professional athletes

Rest and recovery is just as important to a professional athlete as training.

Sleep is the time where the body repairs itself, and if an athlete is receiving inadequate sleep (or poor quality sleep), their performance will suffer.

There are a bunch of benefits to sleep for professional athletes. We touch on each:

Improved reaction times and decision-making

In high-speed sports like tennis, elite athletes often make split-second decisions as the action literally unfolds in front of them.

Sleep-deprived athletes can suffer from slower reaction times, negatively impacting their optimum performance.

Reduced injury rates

Did you know that a chronic lack of sleep in teens can have as big an influence on injury as actual training?

Sleep helps improve reaction times (as noted above) and so as such, can help to reduce the risk of injury on the court (or field, or track…). Poor quality sleep can also impact the immune system, increasing the risk of illness.

Improve accuracy

Motor skills can be improved with better quality and longer sleep, making shut-eye just as important as an athlete’s training sessions.

A Stanford University study found that college basketball players who added two extra hours of sleep per night found that:


  • Speed increased by 5%
  • Free throws were 9% more accurate
  • Their reflexes were faster
  • They felt happier



How much sleep do the world’s best athletes get?


  • LeBron James, Roger Federer, and Michelle Wie get around 11-12 hours of sleep every night
  • Usain Bolt relies on a solid 8-10 hours of sleep “to rest and recover in order for the training I do to be absorbed by my body”
  • Venus Williams needs around 10 hours of sleep every night
  • Many athletes take “game day” naps to improve their body’s performance



How do athletes train?


  • A typical athlete trains four 5-6 hours every day
  • They engage in a mix of low and high intensity training
  • Strength and aerobic training is equally important
  • Training differs by sport – endurance athletes have different fitness levels than, say, sprinters



When exercise impairs sleep

As you might expect, there’s no blanket rules when it comes to the optimum time of day to exercise; it depends on the individual.

Once upon a time, we were told that vigorous exercise too close to bed would over-stimulate the body and we would struggle to sleep, but for some, nightly workouts prove to be the most convenient and effective.

If you find yourself too hyped-up after a late workout and struggle to sleep, try shifting your gym appointment to straight after work. What works for one person mightn’t work for another – so it’s important to test.

Is there an ideal time to exercise?


Those who love to start the day with a gym session benefit from the following:


  • Enhanced metabolism
  • A physical and mental boost to start the day
  • Improved attention span



Many people exercise in the morning to get it out of the way before the working day has even started.

Afternoon or early evening

By this time of day, your body temperature is higher, meaning that muscles may be working more effectively and the risk of an exercise-related injury can be lowered.

Exercise raises the body’s temperature for several hours. Once your core temperature starts to dip, your body begins its transition into sleep mode. The afternoon can be an ideal time to exercise as it coincides with regular bedtimes.


Some people swear by a high- or low-intensity workout late in the day or before bed. They feel it exhausts them to the point where they’re sleeping well, and evening exercise simply fits into their schedule.

Are you an evening exerciser who struggles with sleep? Change it up – test our other times in the day and, without changing other daily habits, see if you can make a distinction between the time of day you hit the treadmill and the amount of sleep you receive (and quality).

Post-workout insomnia? It might depend on the type of exercise you’re doing

In this study, participants ran on a treadmill at either moderate or high intensity between 9:20pm and 10pm, and went to bed at 11pm.

Researchers found that those in the “moderate” group had little difference in their quality of sleep compared to when they were sedentary before bed.

However, those who engaged in high intensity exercise took 14 minutes longer to fall asleep compared to when they were inactive. Further, their sleep was of lower quality.

From this study we can speculate that high intensity workouts close to bedtime may not allow the body proper recovery and rest time, resulting in a struggle to get to sleep.