How Sleep Can Decrease Injury Risk and Improve Performance?

Sleep – something we all crave plenty of, but some are better at it than others! It was only today I had a patient who was telling me about their deep, uninterrupted nightly sleeps of 8 – 9 hours … and I just gently nudged my elbow into their back another 1cm deeper in jealous retaliation!

But how important is sleep to our health and wellbeing? Is it just that we mentally feel better knowing we’ve had a great sleep, or can it really affect our injury risk and sporting (and life) performance? Hopefully by the end of this article you will see that sleep is one of the more commonly overlooked factors in any fitness and rehabilitation program, yet perhaps one of the more crucial to consider!

When developing a training program, how many players or coaches have “Sleep” as one of their clear goals in the training or recovery plan? Not many at all unless you’re an elite athlete with all the sports science around to remind you! Question an athlete on their recovery techniques and you’re likely to hear words like: massage, stretch, hydrate, ice baths, diet… but rarely sleep!

There are two main types of issues that people can have with sleep: sleep deprivation and sleep restriction. Sleep deprivation refers to extreme cases of sleep loss (eg not sleeping at all for prolonged periods) whereas sleep restriction (the focus of this article, and more relevant to most athletes) occurs when you fall asleep later, or wake earlier than usual, disrupting the normal sleep-wake cycle.

A study in 2014 on sleep patterns in adolescent children showed that teenage athletes who get less than 8 hours of sleep each night actually increase their injury risk by a factor of 1.7, when compared to those who get 8 or more hours sleep (1). Another similar study in 2011 reported an association between inadequate sleep duration (less than 6 hours) and fatigued-related injuries among young soccer basketball, football, soccer and running athletes (2).  So sleep is important to consider if you want to optimise your athletic performance and reduce your injury time!

What Constitutes A Normal Night’s Sleep?
A typical night’s sleep is broken into phases of 90 minute cycles consisting of Rapid Eye Movement (REM – the dream phase) and non REM (NREM – the deeper sleep phase). NREM sleep is thought to be the phase of energy conservation, release of growth hormone, and recuperation of our nervous system. Oxygen consumption is at its lowest level, and anabolic (growth and maintenance) hormones are released (3). REM sleep is thought to be important in establishing brain connections and neural pathways, so it is important to ensure we are getting enough of both types of the sleep cycle.

Unfortunately it’s not just as simple as getting quantity of sleep! Sleep quality and timing of sleep are key components to sleep, and if one of these factors is neglected it is possible that your performance or recovery from activity may be adversely affected! (4).

First, let’s start with sleep quantity: A nationwide study in the USA in 2013 found a mean of 7 hours 17 minutes total sleep time was optimal for people to “operate at their best the next day”(4), which corresponds with the 7-9 hours sleep per night recommended by The American National Sleep Foundation. It is thought that athletes require greater restorative and recovery intervention than non-athletes, so some authors suggest that athletes should be sleeping for 9-10 hours per night, however the evidence suggests they often sleep far less than the lower recommendation! Numerous studies agree that when sleep is reduced to less than 7 hours in healthy adults, cognitive performance is poorer in tests for alertness, reaction time, memory and decision making.

Next is quality of sleep: sleep quality can be effected in many ways – stress, pain, caffeine and alcohol are all examples of factors that can negatively impact our quality of sleep. The use of electronic devices is also a big factor in delaying or restricting sleep patterns! Many students are on their computers and laptops well into the evening hours, many of us check our social media status whilst in bed if we’re not watching TV, and for many athletes, social media and surfing the web can be a way of “winding down” after intense activity. Unfortunately this is not winding down at all, it’s actually ‘winding up” as the bright and artificial lights of these devices are thought to reduce the production of melatonin, which is a hormone produced by the brain to have a sleepy or hypnotic type of effect on the body. With minimal light (eg at night time), more melatonin is produced, helping assist our bodies into a sleep pattern – in effect setting our body clock into a sleep phase. However if receptors on the back of the eye are receiving higher levels of bright light input, (from the use of electronic devices late at night) then melatonin production is naturally reduced and the body’s natural preparation for sleep is disrupted.

And finally, timing of sleep: These days we see sport played at all times of the day – it’s not uncommon to see tennis matches at the Australian open finish after midnight; evening AFL games finish after 10pm (and by the time the players complete their after match interviews, recovery, showers etc they’re not home til well after midnight and often still in a state of arousal and excitement); the Big Bash cricket games are similar. And it’s not just elite sport – even our juniors are exposed: Friday evening cricket games; basketball games in distant stadiums scheduled at ridiculously late times. Not only do these athletes lose sleep quantity, but late night sporting sessions have been shown to have a negative effect on the quality of their sleep – the ability to get to sleep is delayed following high intensity exercise prior to bed time (6/7).

And let’s consider the other extreme – our junior squad swimmers are usually in the pool by 6am, so if they’ve been up late studying or had a rough night, they lose their recovery sleep in the morning! One study showed that a group of world class swimmers were averaging as low as 5.4 hours sleep per night (8).

What Happens When We Sleep?   

Good sleep patterns are required for optimal health and functioning of many aspects of our musculo-skeletal system:

Growth, repair and regeneration of muscle tissue – growth hormone and the proteins that help rebuild muscle tissue following training sessions are released during sleep periods. (4-6). Sleep also has a restorative effect on our immune system and the endocrine system (hormone secreting glands that help control growth, metabolism and development of the cells of the body.

Cognitive development (learning new skills, memory retention and developing brain pathways from tasks that have been performed that day) relies on good sleep patterns. As many activities involve learning new techniques and acquiring new skills, repetitive practice is an integral part of improving motor learning and performance levels. In fact, I am just reading a book at the moment called “The Sports Gene”– a fascinating discussion on whether great sports people are born to be great (have the right genes) or can be trained to be great (we can influence or improve existing genes). More on this topic in another article, but one of the interesting points made in this book is how important hours of practice are – the author mentions that the reaction time of elite baseballers is not quick enough to react in the time it takes for the ball to leave the pitchers hand until it arrives at the hitters bat. It is only through hours of practice that the elite baseballer learns enough about body angles and postures of the pitcher, to be able to anticipate what the ball is going to do(8)! Sleep is therefore an essential time for consolidating these new skills and memory patterns. (Where this book gets interesting though is that it states these baseballers may actually have the genetic gift of better vision, which combined with the hours of correct training, may help them achieve their elite levels – but as I said, that’s a whole new article!).

Some studies (10) have investigated the effect of poor sleep behaviour on sporting performance and found:

– when educated to improve their sleep average from 6.5 hours to 8.5 hours per night over a 7 week period, a group of basketballers improved their speed tests by 5%, free throw accuracy by 9% and 3-point accuracy by 9%.

– In a similar fashion, tennis players who improved their sleep duration by 2 hours per night, improved their serving accuracy by 5% over the trial period. We know that in sports like tennis and basketball that small percentages can make big differences.

– Young athletes and adolescents with poor sleep behaviours perform significantly worse on verbal and visual memory tests following a concussion, and consistently showed increased symptoms during the first 14 days post-concussion. During this 2 week post-concussion period (which is when the athlete has usually returned to sport) the players in the poor sleep group still had significantly slower reaction times, making return to sport a greater risk. What was really alarming about this study, was that neurocognitive test results (“concussion testing”, which is really only performed at higher levels of sport) were still positive even after the athlete’s symptoms had completely disappeared. So just relying on symptom resolution, particularly in people with poor sleep patterns, is not a good enough factor on its own to determine return to sport following concussion.

So as can be seen, attention to sleep patterns should be a crucial component of any training program – at all levels of sport, not just at elite levels. As physio’s, coaches and parents, we need to be very aware of the sleeping habits of our athletes and children, particularly during times of high training loads and intense competition, and enquiring about their sleeping habits and educating them on the power of sleep to assist them with their injury prevention/rehab and training goals.

Here are some simple recommended strategies to help optimise the sleep patterns in athletes:

  • Consider sleep to be an integral component of any training program and identify whether sleeping problems exist.
  • Encourage 7-9 hours per night and consider naps during the day if less than 7 hours sleep per night
  • Avoid using electronics or personal devices in bedroom, especially in the 30 minutes before bed time.
  • Sleep in a dark, cool, quiet environment.
  • Avoid early morning training sessions following sleep disruption where possible.
  • Reduce caffeine after lunch, and minimise alcohol at night




1.            Milewski MD, Skaggs DL, Bishop GA, Pace JL, Ibrahim DA, Wren TA, et al. Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. Journal of pediatric orthopedics. 2014 Mar;34(2):129-33. PubMed PMID: 25028798. Epub 2014/07/17. eng.

2.            Luke A, Lazaro RM, Bergeron MF, Keyser L, Benjamin H, Brenner J, et al. Sports-related injuries in youth athletes: is overscheduling a risk factor? Clinical journal of sport medicine : official journal of the Canadian Academy of Sport Medicine. 2011 Jul;21(4):307-14. PubMed PMID: 21694586. Epub 2011/06/23. eng.

3.         Weitzman ED, Circadium rhythms and episodic hormone secretions in man. Ann Rev Med, 1976; 27: 225-43

4.            Fullagar HH, Duffield R, Skorski S, Coutts AJ, Julian R, Meyer T. Sleep and Recovery in Team Sport: Current Sleep-Related Issues Facing Professional Team-Sport Athletes. International journal of sports physiology and performance. 2015 Nov;10(8):950-7. PubMed PMID: 25756787. Epub 2015/03/11. eng.

5.         Sleep in America Poll: Exercise and Sleep. Arlington (VA): National Sleep Foundation; 2013

6.            Nedelec M, Halson S, Abaidia AE, Ahmaidi S, Dupont G. Stress, Sleep and Recovery in Elite Soccer: A Critical Review of the Literature. Sports medicine (Auckland, NZ). 2015 Oct;45(10):1387-400. PubMed PMID: 26206724. Epub 2015/07/25. eng.

7.            Fullagar HH, Skorski S, Duffield R, Julian R, Bartlett J, Meyer T. Impaired sleep and recovery after night matches in elite football players. Journal of sports sciences. 2016 Jul;34(14):1333-9. PubMed PMID: 26750446. Epub 2016/01/12. eng.

8.         Sargent c, Halson S, Roach GD. Sleep or Swim? Early morning training severely restricts the amount of sleep obtained by elite swimmers. Eur J Sport Sci. 2014; 14:S310-5.

9.         Epstein, David; The Sports Gene: Inside the science of extraordinary athletic performance; 2013

10.        Simpson NS, Gibbs EL, Matheson GO. Optimizing sleep to maximize performance: implications and recommendations for elite athletes. Scandinavian journal of medicine & science in sports. 2016 Jul 1. PubMed PMID: 27367265. Epub 2016/07/02. Eng.