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Sleep to Victory :

The Impact of Sleep Deficiency on Sport Performance

One of the most important, and yet one of the most underrated and overlooked factors of performance, is sleep. Every mechanism of performance is supported by athletes obtaining a sufficient amount of high-quality sleep, which is required to restore energy levels, to repair muscle tissue, to maintain motivation & concentration, and to optimize body composition. Even partial sleep deprivation can have significant negative effects on recovery and performance, with factors such as metabolism, inflammation, hormone & neurotransmitter release, muscle tissue repair, cognitive function, the immune system and risk of injury all being adversely affected.

Due to the combined demands of training, competition and travel, athletes frequently experience either a lesser amount of sleep, a poorer quality of sleep, or usually, both. When we consider the important function played by sleep in sport preparation, this can have considerable implications on the probability of competitive success.

But what is the overall impact of insufficient sleep can have on sport performance?

1. Athletes Experience Higher Levels Of Sleep Disruption

Athletes generally sleep less and achieve a lower quality of sleep than the general population (5). This is primarily due to the combined demands of training, competition and travel, but there might be other mechanisms which also play a role.

One of which is psychological stress. Firstly rumination – where the athlete reflects with a feeling of dissatisfaction on a previous performance – or worrying – where the athlete experiences negative thoughts about future performances – can inhibit sleep (19).

A further sleep disruptor is related to the sheer volume of physical exercise completed by athletes during the course of their training and competition program. Prolonged or intense exercise can deplete the nutrient pool needed to synthesize serotonin and melatonin, the neurotransmitters which are necessary for sleep (16).

In addition to this, the time of day that athletes exercise can also be a factor. Research has shown significant reductions in total sleep time (-1h 40 min) and significant increases in sleep latency (+45 min) following evening competition (12). The mechanisms behind this are primarily hormonal; exercise performed in the late evening or at night can suppress the release of melatonin and increase production of the stress hormone cortisol, both of which will cause sleep disruption (10).

Regardless of the initial cause, even partial sleep deprivation can trigger a variety of dysfunctions which potentially have significant consequences for athlete recovery and performance.

2. Poor Sleep Causes Hormonal Dysfunction

Inadequate sleep may disrupt an athlete’s optimal hormonal profile. Firstly, lack of sleep can lead to elevated levels of the stress hormone cortisol (9). A normal cortisol profile has a significant spike first thing in the morning, so as to increase blood pressure and to provide energy, which then gradually declines throughout the day to reach low levels at night.

A sleep deficit can result in cortisol levels remaining elevated throughout the day (20), causing a reduction in muscle protein synthesis and to losses in muscular force. A second – and highly significant – effect that sleep deprivation can have on the endocrine system is to suppress the secretion of growth hormone.

Growth hormone plays an important role in muscle growth and repair (12), with a reported 95% of daily growth hormone production released whilst the athlete is asleep, particularly during stage three slow wave sleep (18).

Sleep disruption attenuates this nocturnal growth hormone release, thereby compromising the process of physical restoration. The combined effects of elevated catabolic hormones and inhibited anabolic hormones creates an environment where muscle protein synthesis is impaired, blunting training adaptations and delaying recovery.

3. Lack of Sleep Triggers Negative Food Choices

The disruption to normal hormone production which accompanies lack of sleep can also affect appetite and food choices, increasing the likelihood of an athlete consuming inappropriate foods and of them overeating. Sleep plays a vital role in regulating the hormones leptin and ghrelin, which are essential to hunger and appetite. Insufficient sleep results in elevated ghrelin, which triggers increased hunger, whilst leptin, the hormone responsible for feeling full, is reduced (14), increasing the likelihood of the athlete overeating.

A lack of sleep also impacts the neuroscience of food by stimulating the food reward processes, meaning that the athlete is more likely to consume calorie dense, nutrient poor food, such as highly processed foods or foods with a high sugar content (4;8). When we consider the importance of nutrition to performance and recovery, this can have serious consequences.

4. Sleep Deprivation Influences The Inflammatory Signalling Pathway

Sleep deprivation has also been shown to result in increased inflammation. Fewer than six hours of sleep per night, or a night of disturbed sleep specifically lacking in deep, slow wave sleep, can increase levels of the pro-inflammatory cytokine IL-6 and the inflammatory biomarker C-Reactive Protein (17).

This has a direct impact on athletic performance, as increased IL-6 concentration results in altered perception of effort (6). In other words, athletes find that exercise becomes harder. Sleep restriction studies have shown that reduced sleep can elevate multiple different inflammatory markers (including IL-1Beta and TNF Alpha), but that does not quite tell us the whole story.

The relationship between sleep and inflammation is actually more layered and more complex. Pro-inflammatory cytokines are released naturally by the body during sleep, when they are required to strengthen the immune system, (2) and to drive training induced adaptations. As the morning approaches, this inflammation is down-regulated prior to the athlete waking up, so as to protect normal physical and mental functions during the daytime.

So, how does this all relate to performance?

Essentially, inflammation during sleep is necessary in order to drive training adaptations and to support immune function, but a well-balanced pro and anti-inflammatory pathway depends on the athlete having a sufficient amount of sleep. Shorter sleep durations cause inflammation to remain elevated beyond waking, which then impedes the effectiveness of the immune system and increases the risk of athlete illness.

5. Reduced Sleep Hinders Energy Replenishment

Restricting sleep to five hours or less for only one week has been shown to increase insulin resistance and decrease tolerance to carbohydrates (3). The consequences of this on athletic performance can potentially be severe; poor insulin sensitivity inhibits glycogen synthesis, and glycogen synthesis is required to support an athlete’s fuel demands both for training and for competition.

Any restriction to glycogen synthesis means that the athlete will not be able to refuel quickly, and the energy stores that they have depleted during the day may not be completely restored – leading directly to a performance decline in subsequent days. For this reason, the relationship between sleep and the replenishment of energy stores is critical.

6. Lack Of Sleep Causes Deterioration In Multiple Performance Factors

The negative modifications that sleep deprivation makes to the endocrine, energy, inflammatory, and other systems will transfer directly into a deterioration in athletic ability, and therefore reduce the chance of winning. A number of studies have shown that reduced sleep can trigger a decline in many different measurable components of sports performance: physical, mental and technical.

Firstly, the inhibition of glycogen synthesis which accompanies sleep deprivation creates a reduction in energy availability in the form of a lower concentration of muscle glycogen. This has been shown to then bring about an associated deterioration in both average and total sprint performance (15). This decline in sprint ability is compounded by research which shows that sleep deficits also cause a reduction in both muscular force and power, with one study indicating that countermovement jump was impaired by 10.9% and grip strength by 6% (7).

Speed and strength is not the only physical component which is impacted by sleep disturbance – endurance is also affected. One study found that a night of complete sleep deprivation resulted in an 11.4% reduction in aerobic performance, whilst restricting sleep to only four hours led to a performance decline of 4.1% (7). Studies into male runners and volleyball players found that both groups reached exhaustion quicker following only one night of sleep deprivation (1), indicating that overall work capacity is diminished.

The execution of sport-specific technical skills also deteriorates with lack of sleep. A study on both male and female tennis players indicated that sleep deprivation resulted in a decline in serve accuracy of up to 53% (13).

Another performance factor which is impacted by poor sleep is cognitive function, with reaction time and decision making having been shown to be negatively affected after only one night’s sleep deprivation (21;7).

Finally, studies have also indicated that chronic sleep deprivation is associated with increased injury rates (11), reducing athlete availability. In summary, both sleep deprivation and a decrease of sleep quality have been shown to significantly impact a number of important factors of sport performance, including:

Disruption to the optimal hormonal profile
Reduced appetite regulation & poor food choices
Unbalanced pro and anti-inflammatory response
Lowered training adaptation
Less effective immune system & increased risk of illness
Increased insulin resistance, reduced glycogen synthesis & decreased replenishment of energy stores
Decreased cognitive performance, impaired judgment, longer reaction times and poor decision making
Reduced sprint, strength and power performance
Reduced cardiorespiratory function & quicker time to exhaustion
Reduced execution of sport specific technical skills
Increased risk of injury

What This All Means

It is apparent that sport performance is supported by athletes obtaining a sufficient amount of high-quality sleep. Any organization that seeks a winning record should place athlete sleep as one of its central pillars – but applying this in a practical setting requires a multi-faceted approach involving several different people:

Athletes must be constantly educated to understand the importance of sleep and what they must do to attain it.
Coaches and managers must ensure that training schedules are designed to allow athletes sufficient opportunity to sleep, particularly when night-time competition causes significantly delayed bedtime.
Sport scientists should have appropriate measures in place to monitor athlete sleep, both in terms of volume and quality.
Nutritionists should create meal plans which ensure the metabolic availability of nutrients needed to synthesize the hormones and neurotransmitters necessary for sleep.
Administrators must arrange travel plans which minimize sleep disruption, and organize hotels which deliver a high quality of sleep hygiene.

To create a high-performance environment operating at this level, it is vital that an integrated approach be adopted which co-ordinates the contributions made by various departments towards optimizing athlete sleep.

For this to operate as efficiently as possible, all relevant information and sleep data needs to be collated into a central platform to be made readily accessible to those who need it, and reports must be created which deliver vital sleep information in a clear, precise and easily understandable way.

Where Apollo makes a real difference

ApolloV2’s athlete performance software unlocks data silos allowing coaches, trainers, doctors and players to become masters of data-driven performance with real-time data visualization and collaboration tools. Our software is integrated with over 80 performance-focused technologies used by college and professional athletes. With ApolloV2, teams have the tool they need to optimize athlete sleep and maximize performance.

WHAT APOLLO CAN DO FOR YOU

ApolloV2 is not a traditional ‘one size fits all’ athlete management system. Instead, we are a highly adaptable platform which can create customized dashboards specifically tailored to each team’s individual needs and unique way of working.

Our system equips teams with the ability to generate custom-made data visualizations without software code. We have more API’s than any other system, which allows us to collect data from the multiple tools and systems staff are using, and then combine it efficiently to allow coaches to make informed decisions with their players.

We have Power Bi and Tableau integrated into our ecosystem, which enables us to build bespoke, best-in-class data reports designed to meet specific requirements and ensure that coaches receive the data driven insights they need, to inform decision making and influence positive change.

To learn more about using ApolloV2 for performance enhancement, email – alamb@apollov2.com.

Written by Adrian Lamb, ApolloV2 Sports Scientist

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