How Does Sleep Affect Exercise & Performance?

Today we are fortunate to have a guest blog from our very own Alice Clarke. Alice is a registered associate nutritionist with a focus on performance. Thus she knows a thing or two about how sleep and exercise work together. Take it away Alice...
Statistics suggest that the average person will sleep for 229,960 hours in their lifetime – that’s almost a third of your life! All this sleeping would suggest that it is essential to our lives, health and well-being. But can maintaining a good sleep routine have benefits to our sporting performance too?
The short answer is yes… There is a clear link between sleep and exercise but before we get into how, let’s take a deeper look into sleep itself.
Sleep consists of two main types—non-rapid eye movement sleep (non-REM) and REM sleep. Non-REM sleep is further divided into three stages, from ‘light’ sleep in stages 1 and 2, through to ‘deep’ sleep in stage 3. Although important restorative functions occur during all stages of sleep, stage 3 non-REM and REM sleep are the two sleep stages during which our bodies and minds undergo the most renewal. Together, deep sleep and REM sleep are often referred as ‘restorative sleep’.
The duration and composition of ‘normal sleep’ also changes across the life cycle. An adolescent (aged 15 years) will sleep around 8–10 hours with approximately 57% light sleep, 22% deep sleep and 21% REM sleep. A young adult (aged 30 years) will sleep around 7–9 hours with approximately 61% light sleep, 16% deep sleep and 23% REM sleep. We cycle through all stages of non-REM and REM sleep several times during a typical night. The longer, deeper REM periods occurring toward morning.
Now we know a bit more about the types of sleep, let’s explore the effects of sleep on sporting performance.
Man sleeping to improve exercise & performance
 

The Effects of Sleep on Exercise & Performance

Evidence indicates that increased duration and improved quality of sleep is associated with improved performance. Improved sleep may reduce the risk of both injury and illness in athletes.
There is a growing range of research that has started to look at how poor sleep can negatively impact performance:
  • Reilly and Percy found that max bench press, leg press and deadlifts all decreased with low levels of sleep. Submaximal performance, was affected on all three tasks and to a greater degree. The greatest impacts were found later in the protocol, suggesting an accumulative effect of fatigue from sleep loss.
  • Skein et al. showed reduced sprint performance and slowed pacing strategies during intermittent-sprint exercise were associated with sleep loss in male team-sport athletes.
  • Milewski et al. showed that chronic sleep deprivation (<8hrs per night) was associated with a significant increase in injury rate in adolescent athletes.
  • Prather et al. also showed that poor sleep habits (<5hrs per night) were linked with an increased risk of illness, with individuals exposed to chronic poor sleep experiencing a lower resistance to illnesses such as respiratory infections.
The initial research indicates that poor sleep can have a negative impact on both strength and endurance outputs. These effects are accumulative, meaning they become more significant throughout the session.
Poor sleep can affect core physical health and increase an individual’s risk of both injury and illness. This increased risk has an associated effect on sporting performance due to the impacts on exercise and exertion.
If you think you're nailing your sleep but could do more with your training why don't you check out our blog. It discusses how you can utilise a training programme to take your performance to the next level.
 
Man sleeping to improve exercise & performance
 

The Effects of Sleep on Cognitive Performance

We know the impacts that poor sleep can have on physical performance. But, insufficient sleep can also have a significant effect on cognitive performance. Poor cognitive performance will be most apparent in sports where reactions and accuracy is important.
Let’s see what the research suggests:
  • Reyner and Horne found that in tennis players, a night of poor sleep (reduced by 33% from normal) reduced serving accuracy by up to 53% when compared with performance following a night of normal sleep.
  • Taheri and Arabameri showed that the reaction times of adolescent athletes were adversely impacted following just one night of sleep deprivation.
  • Mah et al. showed that in a study of male basketball players, shooting accuracy increased by 8% for both free throws and three-point shots following a sleep extension period of minimum 10hrs in bed each night.

Nutrition to Improve Sleep

I wouldn’t be a true nutritionist if I didn’t include something here about the relationship between nutrition and sleep quality. The perceived ability to manipulate sleep and therefore performance has stoked commercial interest in nutritional supplements for sleep. The rationale behind this relationship relates to the activity of some key neurotransmitters being associated with the sleep-wake cycle (e.g., serotonin), that could be influenced by nutrition.
Unfortunately the research in the sleep supplement industry is still new and definitive conclusions have yet to be made. This is in contrast to supplements like multivitamins where companies have a lot more research to base their products on (aka the Daily Driver!).

Tips to Improve Your Sleep Hygiene

The habits and practices that are involved in maintaining a good sleep routine are more referred to as sleep hygiene. If you are struggling with the negative effects of poor sleep, spend some time reviewing your current sleep hygiene to identify any areas that you could improve on.
Below is a list of some common sleep habits and practices that can help improve your sleep hygiene:
  1. Creating an appropriate sleep environment – this is often overlooked, but your sleeping space should be dark and cool with little to no noise. Your sleep environment should be used only for sleep.
  2. Avoid alcohol and caffeine before bedtime – a more obvious one, but these drinks can interrupt sleep or lead to more disturbed sleep.
  3. Stay away from electronics in the hours before bedtime – this includes TVs, phones and computers. The blue light that these devices emit can affect your circadian rhythm and have a negative impact on your sleep cycle.
  4. Plan a pre-sleep wind-down routine - activities such as reading, taking a bath, or meditating can help you relax, prepare and get ready for sleep.
In addition to these sleep hygiene tips, there are some other key habits that are especially important for athletes:
  1. Avoid overtraining – where possible, keep to a consistent training schedule so as not to overexert yourself.
  2. Avoid training and competitions too early or too late – for competing athletes this isn’t always possible, but remember that these changes can affect sleep quantity and quality, especially if your schedule is inconsistent.
  3. Keep naps brief, if you take them at all - naps should be no more than an hour and not taken after 3 p.m. But, don’t be afraid to nap if you need to top up on sleep earlier in the day.
  4. Reduce stressors – not only do mental stressors affect sleep quality, but they also impact performance. Take some time to review things in your life that are causing stress and see what you could change to remove or reduce them.

A Reflection on Sleep, Exercise and Performance

Sleep is a complex beast, but it is easy to see the impact it has on exercise and performance. It's also clear that sleep impacts both physical and cognitive performance. The primary risk factors for poor sleep quality have shown to include high training loads, travel and the stress associated with competition. Other risk factors include individual vs team sports, female vs male athletes and the type of sport undertaken.
It is important to take ownership of your own sleep hygiene. Take some time to review your current sleep schedule and identify some areas to improve on. If you can start improving the quality and consistency of your sleep, you are sure to start reaping the benefits in all other aspects of your life!
P.S. Sleep is one of our 4 pillars to maximising your performance! Check out the other 3 in our blog.