Exercise and Sleep
If you live to 79 years old, you will spend around 26 years sleeping, and 7 years trying to get to sleep. Many of you would have been told to make sure you get adequate sleep, but why is it so important? How do we improve sleep quality? How do you spend less time trying to get to sleep?
We will discuss the sleep stages, the benefits of sleep, and how exercise can improve your sleep quality.
There are two types of sleep; rapid eye movement (REM) and non-rapid eye movement (NREM), which is divided into 3 stages. You go through the different sleep stages multiple times during the night, having longer and deeper REM sleep towards the morning.
Stage 1 NREM
The first stage of sleep is the lightest sleep stage. It is the changeover from wakefulness to sleep, lasting up to ten minutes. Your brain waves, heartbeat, breathing and eye movements slow down, and your muscles become more relaxed. In this stage you’re somewhat alert and can be easily woken.
Stage 2 NREM
The second stage of sleep is still referred to as light sleep. Brainwaves continue to slow and muscle activity starts to decrease. During this stage, there are bursts of brainwaves, referred to as sleep spindles. While the function of sleep spindles is unclear, it is thought they play a role in memory consolidation and detach the brain from external input from the sleepers’ environment. This reduces disturbance so the sleeper can transition to the next stage of sleep.
Stage 3 NREM
The third stage is referred to as deep NREM sleep, and is the last NREM stage. During this stage your muscles are fully relaxed or “limp”. Brain wave activity, breathing rate, blood pressure, heart rate and body temperature all decrease further. It is very difficult to wake up during this stage. The body releases growth hormones, regulates immune system function and repairs muscle tissue. Making this stage very important for recovery.
Stage 4 REM
The fourth stage is referred to as rapid eye movement, because your eyes move rapidly under your eyelids. The full function of REM sleep is still being studied, however, it is believed REM sleep plays a vital role in memory and learning. During this stage the brain is very active, and consolidates and processes information into long term memory. This is also the stage dreaming occurs and your muscles are “paralysed”. This is a good thing because it prevents you from acting out your dream, harming yourself and anyone sleeping near you. Your heart rate, blood pressure and breathing also increase.
You will cycle through each of these stages 4-6 times per night, with most of your REM sleep occurring towards the morning.
Benefits of Sleep
- Improves memory
- Improves creativity
- Reduces risk of chronic disease such as cancer, dementia and diabetes
- Improves appetite control
- Lowers risk of heart attack and stroke
- Improves depression and anxiety
- Aids in recovery
- Helps muscle growth and repair, as sleep is when the concentration of growth hormone is highest
- Improves immune system function
- Reduces risk of injury during exercise
How Exercise Improves Sleep
It is well known exercise can help your physical health, but it can also improve your sleep. Now we know how important sleep is, let’s look at how it can be improved through exercise.
Firstly, exercise helps you to fall asleep faster. The most obvious reason for this is that it tires you out. Exercise has also been proven to reduce stress and anxiety. Being stressed and anxious is one of the most common reasons people find it difficult to fall asleep, or are restless during the night. Exercise is great for reducing stress and anxiety, helping you to fall asleep faster, and stay asleep for longer.
Secondly, exercise increases time spent in deep sleep, the most restorative stage of sleep. Deep sleep is important for immune function, cardiac health and managing stress and anxiety.
Thirdly, exercise stimulates the release of a chemical called adenosine. This chemical can cause drowsiness, increase body temperature (which stimulates the release of melatonin) and improve regulation of circadian rhythm.
How much exercise do you need?
There is no magic formula for the amount and type of exercise that improves sleep. We recommend meeting the National Physical Activity Guidelines. Adults should accumulate 150-300 minutes of moderate intensity physical activity, or 75 minutes of vigorous intensity, or a combination of both. This should include two sessions of muscle strengthening exercise per week. Children and teens need more, aiming to accumulate 60 minutes of physical activity each day.
What’s the best time of day to exercise?
Ultimately, the best time of day to exercise is the time that suits you.
If you want to start an exercise plan, but don’t know how, we are here to help! If you have a chronic condition, pain or an injury, it is recommended you see an Exercise Physiologist or Physiotherapist. They are specially trained through university to prescribe exercise for people that have health issues.
Courtney Wharton, Exercise Physiologist at myPhysioSA Mount Barker and International Spine Centre, Norwood.