How Exercise Improves your sleep
Did you know that just a small amount of exercise can be as effective as a sleeping pill?
It’s pretty well established that exercise improves both the quantity and quality of your sleep, but there are many ways you can optimise this relationship.
Let’s start with a few quick facts about sleep:
The average adult needs 7-9hrs of sleep a night, but it’s not all about duration, good quality sleep is very important too.
Good quality sleep means more time in the deep sleep and REM sleep stages.
On average we wake up 8 times a night as we cycle between light sleep, deep sleep and REM. These wakes are usually very short so we don't tend to remember them.
It takes on average 10-20mins to fall asleep. Falling asleep in less than 5minutes is a sign of sleep deprivation.
Insufficient sleep is a risk factor for obesity, Type 2 diabetes, cardiovascular diseases, depression and accidents. It also makes you irritable, and decreases your concentration, memory, judgement and reaction times.
Regularly getting 7-8hrs of sleep makes you less likely to fall ill.
You’re significantly more likely to suffer an exercised-induced injury if you aren’t sleeping well.
Your stages of sleep
There are three stages of the sleep cycle – light sleep, deep sleep and REM (Rapid Eye Movement) sleep. Light sleep occurs as you transition between wakefulness and the other stages of sleep. Deep sleep primarily occurs during the first half of the night – this is why you need to go to bed earlier! Good quantities of deep sleep help you feel refreshed in the morning.
REM sleep is when your eyes move rapidly from side to side under your eyelids and you do most of your dreaming here. Your limbs become temporarily paralysed (to stop you acting out your dreams!) and some sources suggest REM helps with memory consolidation.
How exercise affects your sleep
Exercise causes feelings of fatigue and tiredness that help you fall asleep quicker and stay asleep for longer. Exercise induced endorphins also have a relaxing and restorative effect on the body that better prepares you for sleeping at night. As a result, exercisers tend to have more deep sleep than non-exercisers.
Exposure to natural light during exercise is a major player in maintaining a healthy circadian rhythm that makes you feel more awake during the day and sleepy at night. Because sleep is very rhythmic, sporadic bouts of intense exercise aren’t nearly as helpful as a regular routine of moderate physical activity throughout the week.
Indirect effects of exercise on sleep are also important. Exercise can obviously change your body composition (to become leaner) which promotes better sleep. Exercise also improves cardiac function, metabolic rate, glucose control, mood and immune function, which all positively affect sleep.
Exercising for better sleep
The first thing I’ll point out is you may need to be patient! Some people are fortunate and feel an immediate impact of exercise on their sleep, but for others it can take much longer to adjust to the effect of a new routine – don’t lose heart though, the scientists are very confident about the relationship between sleep and exercise, even for those suffering from insomnia. Recent research has suggested that regular aerobic (moderate intensity) exercise appears to have similar effects to sleeping pills!
Just 30mins of moderate intensity exercise, 5 times a week can significantly improve your sleep.
Even if you can only achieve 10mins of light exercise a day, it is likely to benefit your sleep, so the rule of something is better than nothing definitely applies here.
Just a note on this; insomnia is actually a primary symptom of over training, so if you do train a lot, keep this in mind.
When to exercise?
Traditionally the advice has been to avoid exercise 4 hours before bed and for some people, this holds true. This advice however is largely based on that fact that intense or competitive exercise will stimulate you and increase your stress levels (very bad for sleep) and raise your core body temperature (also not good). Therefore, if you can exercise without it stressing yourself out too much and leave enough time afterwards for your body to relax and cool down (30-90mins), you should be OK.
Temperature is an interesting tangent actually. You’ve probably experienced difficulties getting to sleep on hot summer nights? Even a very small increase in body temperature (1.5-2.5 degrees celsius ) has a big impact on your ability to sleep. However, the process of your body cooling down actually makes you feel sleepy. This is why a hot bath or even a good run around in the evenings can actually be very beneficial (but avoid ‘over-stimulating’ yourself).
Exercising first thing in the morning is a great fit for many people as it naturally fits within a healthy circadian rhythm. The increase in body temperature kick starts your body, and with the help of exercise induced endorphins, you will feel awake and alert and ready to start the day. Early exercisers also experience all the benefits of better and longer sleep the following night. I love an early workout because it is very rarely disrupted by other responsibilities and ‘daily happenings’, so my routine remains nice and consistent.
What exercises are best?
The best form of exercise is the one you enjoy!
One of the most common disturbers of sleep is stress. Stress prevents you from falling asleep and it makes you restless throughout the night. Almost all forms of exercise trigger an ‘anti-anxiety’ response within 5minutes, so really it doesn't matter what you do. Having said that, some activities such as yoga can really help to quieten your parasympathetic nervous system and help you relax, so this would be an ideal evening activity.
As I’ve already said, consistency is the most important aspect of using exercise to help you sleep, which means you need to find an activity you like – if you can’t stand running, you simply won’t maintain a habit of running everyday based on willpower alone (you can trust me on that one!). Try new activities, and also try doing them at different times of day. Different things work for different people; as long as you can find an enjoyable way to get your heart rate up, you will be having a positive effect on your health and your sleep.
Sport Mentality is a free blog written to help casual exercisers, sports enthusiasts and athletes get the most out of their activities and performances. Please feel free to share these posts with friends, team mates and coaches, and don't forget to subscribe to my weekly newsletter (see the form below) to get alerts about new posts, article summaries and Research Watch links from Sport Mentality each week.