The Importance of Sleep for Health and Athletic Performance

While we all understand that sleep is an important component of health, performance, and recovery, we may not all be getting the appropriate amount of sleep. According to National Health and Nutrition Examination Survey (NHANES), 40% of Americans sleep <6 hours per night, ³ which can be associated with the contribution to or the exacerbation of many chronic health conditions. Poor or inconsistent sleep will also plague athletic performance and recovery. It is estimated that 70% of Americans struggle with poor or inconsistent sleep. ² The purpose of this editorial is to outline the purpose and framework of sleep, how it impacts health and performance, and how to set a plan to improve your sleep.

It is unclear the true purpose of sleep; however, there are several theories. Sleep may have been an evolutionary response for nocturnal protection, to reduce the demand for energy, or to rejuvenate and recharge the body. Recent work, however, suggests that sleep is important for brain plasticity - the ability to process information and create and cement memory. ⁵ Sleep may also contribute to synaptic pruning, the cutting out of unimportant connections, while strengthening the important connections. ¹⁶ Finally, the glymphatic system in the brain that clears out clutter and waste is 60% more active during sleep and may be responsible for clearing out amyloid or other protein deposits, which may have a role in prevention of age-related memory decline, or perhaps even the deposition related to chronic traumatic encephalopathy. ¹⁶

Sleep has a distinctive architecture, with each stage of sleep having a purpose, with a complete night’s sleep achieving several cycles through each of the stages. Stages 1 and 2 are the lighter sleep stages while stages 3 and 4 are the deep sleep stages, which is where the true recovery occurs. The body’s largest secretion of growth hormone happens during deep sleep, and if deep sleep is not achieved, the most restorative nature of sleep is not realized. Finally, rapid eye movement (REM) sleep is the stage where dreams occur, and also where memories (both muscle and mental) are cemented. A complete sleep cycle (approximately 90 minutes) moves through stages 1, 2, 3, and 4 before hitting REM. Adults should strive for 5 sleep cycles per night (7.5 hours), while teens and children should strive for 6 cycles (9 hours). ⁸

Most of the studies investigating the impact of sleep on performance utilize sleep-deprived volunteers. However, as little as 5 days of <6 hours of sleep mimics sleep deprivation, ¹¹ and we know from above that 40% of Americans get <6 hours of sleep per night, ³ meaning almost half of Americans are in a state of sleep deprivation. This chronic undersleeping has been associated with a number of significant health related issues: 12% increase in all-cause mortality, increase in coronary artery disease by 48%, increase in congestive heart failure by 67%, 2 times the risk of stroke or myocardial infarction, and a 50% increased risk of diabetes and obesity (with a 90% increase in obesity in children). We can truly see that poor sleep is indeed a public health problem!

Poor sleep has also been associated with a variety of decrements to athletic performance. Poor sleep impacts thermoregulation, leading to increased core temperature in hot environments, ¹⁵ and impairs body response in the cold. ⁷ Rate of perceived exertion increases, while the ability to tolerate pain/discomfort decreases. ¹³ Injury rate almost doubles in those athletes who regularly sleep <8 hours per night, while strength and speed are also adversely impacted by poor sleep.

All is not lost, however. Cheri Mah, in a series of experiments at Stanford University, demonstrated that sleep extension (increasing the amount of sleep) in athletes can lead to improved athletic performance. Swimmers swam 0.5 seconds faster for 15 m and their reaction time was 0.15 seconds faster. ¹⁰ In our work, we have demonstrated that mental performance increases with a period of sleep extension, plate discipline (swinging at strikes, not swinging at balls), as well as percent of tennis first serve in increases after a period of sleep extension (author’s unpublished data, 2022).

In all phases of athletics, coaches and athletes have a plan: training plan, nutrition plan, recovery plan, but many are lacking a plan to improve their sleep. Littlehale recommends retroactively planning sleep in 90-minute segments (sleep cycles). For example, if you plan to wake up at 7:30 am, you should calculate backward 5 sleep cycles × 90 minutes and plan to be asleep by midnight. ⁸ An important part of sleep planning that is left out for many is the presleep phase. The brain simply cannot go from full speed to sleep, it needs a period of gradual decrease in activity to prepare it for sleep. Today’s technology, television, devices, social media, gaming are very activating, and should be avoided for a period of 30 to 60 minutes before the desired sleep time to improve the ability to fall asleep. Sleep hygiene is also very important - the room should be cool and dark, bed and awake times should remain consistent, removal of electronics from the sleep room, and the use of white noise can be helpful.

While planning and sleep hygiene are essential, there are also several nutritional aids or supplements that can be beneficial to help improve sleep. Nighttime consumption of 20 grams of casein protein (12-16 ounces of milk) has shown to decrease sleep latency (time it takes to fall asleep) and improved the morning metabolic measures in young active men. ⁹ Further, the addition of protein may also decrease overnight muscle breakdown or assist in muscle recovery. Regular consumption of tart cherry juice may increase natural melatonin levels and, when consumed over 2 weeks, has been shown to improve sleep quality and total time asleep.^6,12 Regular magnesium supplementation leads to improved sleep efficiency, sleep quality, and sleep latency in adults. ¹ The recommended dosage is 250 to 500 mg of magnesium daily. Although used regularly, melatonin is often utilized improperly as a nutritional aid to improve sleep - it is often used in lieu of a well-executed sleep plan and is often consumed at a higher rate than needed. Higher rates of melatonin may lead to vivid dreams, nausea, or headaches. It is suggested that, if melatonin is used, to use the slow-release sublingual variety and utilize at doses from 0.5 to 1.0 mg. While these nutrients can aid sleep, consumption of alcohol, on the other hand, has an adverse impact on sleep. Although it is a central nervous system depressant that can help people fall asleep, once the alcohol is metabolized, the body responds with a sympathetic surge that may cause awakening and difficulty falling back asleep. Further, alcohol consumption decreases the number of deep sleep cycles, making the amount of sleep much less effective. The consumption of 2 or more drinks within 2 hours of bedtime has the impact of erasing 3 hours of sleep. ⁴

Napping can also be part of an effective sleep strategy. Many elite athletes utilize naps to add sleep cycles to their weekly total, as well as to aid in recovery. Naps that are utilized to supplement or make up for lost sleep cycles are typically 90 minutes in length, or one sleep cycle. This duration is helpful because it allows the movement through all sleep stages and awakens a person at the end of a sleep cycle while they are in REM or light sleep. Longer naps, however, may lead to sleep inertia, which is the difficulty of people to fall asleep at their regular time. However, when utilized regularly and as part of a weekly plan, accommodation should occur. Power naps are a very effective strategy for times when a quick recharge is needed. Optimal length for a “power” nap is 20 to 25 minutes, allowing entrance into stage 2, but not into deep sleep. These naps allow more alertness upon awakening and actually have been shown to provide a boost in mental performance. The power nap can be supplemented with pre-nap caffeine (50-100 mg), which doesn’t typically kick in for 25 to 30 minutes, once the power nap is completed. ¹⁴

In conclusion, good sleep is tremendously impactful on overall physical and mental health, as well as athletic performance. Improved sleep can be achieved with the proper attention and planning. Use of an effective sleep plan, in combination with one or more nutritional aids, can lead to great improvements in the ability to fall asleep and stay asleep. Naps are an effective way to augment total sleep hours and can offer both short- and long-term improvements to mental and athletic performance. Just like everything else in athletics, a good plan is the key to success. It has often been said that “failing to plan, is planning to fail” - don’t allow a lack of planning to derail the quality and duration of your sleep.

—Chad A. Asplund, MD, MPH
Georgetown University, Washington, DC