The Powerful Benefits of Sleep

By Dr. Chad Asplund | Oct. 23, 2018, 10:51 a.m. (ET)

Sleep is essential for training

Most multisport athletes understand that sleep is important, but in the balance of life, work and training, sleep is often the first thing to go. 

In addition, travel and the timing of competitions can further limit sleep. Unfortunately, many athletes have poor quality sleep or simply do not obtain a sufficient quantity of sleep. 

Why do we need sleep? How is sleep structured? How much sleep is needed? What happens to performance if sleep is sacrificed? How can one improve sleep? These are all questions that will be answered in this article.

While there are several theories on why people sleep, it is primarily for brain rest, regeneration and memory formation. However, for the endurance athlete, possibly the greatest value of sleep may be for recovery from training. Often the rate-limiting step for the busy triathlete is not his or her ability to apply a training load but for the individual to be able to successfully adapt to the load applied by obtaining sufficient sleep for recovery.

One of the main reasons sleep is so important for recovery is our bodies’ delivery of a pulse of growth hormone during deep sleep. Growth hormone is a small protein made in the pituitary gland and secreted into the blood stream. It helps to regulate body composition, body fluids, muscle and bone growth, sugar and fat metabolism and possibly cardiac function. 

In most athletes, the major period of growth hormone release occurs during the first stage of deep sleep of the evening, which occurs approximately 60-75 minutes after falling asleep. Further, poor sleep will act as a stressor to the body, increasing stress hormones, such as cortisol, which will impair growth hormone secretion and negatively impact the ability to recover. 

Normal sleep has a predictable architecture, with sleep cycles consisting of stages with each stage of sleep serving a specific purpose. A sleep cycle is composed of four stages: three non-REM (rapid eye movement) sleep stages, followed by one REM stage. 

The non-REM sleep stages are composed of two lighter sleep phases, which help prepare the body for sleep, and one deep sleep phase where the most meaningful rest and recovery occurs. REM sleep is where dreams occur, but it is also the phase where memories, even muscle memory, are stored and where mental recovery occurs.   

Most people, including athletes, will typically require seven to nine hours of sleep per night, or more depending on their training volume. The average sleep cycle is approximately 90 minutes in length; so most high endurance athletes will require five to six sleep cycles per night, or 35-42 sleep cycles per week. Athletes who train hard need even more sleep to recover. [Littlehale] 

Many of the studies that look at the effects of poor sleep on performance either use sleep deprivation or deficit when evaluating the outcomes. Research has shown that as few as three to five nights of six hours or less of sleep will have the same adverse impacts on performance as those with one night of total sleep deprivation. 

Therefore, the best sleep strategy for athletes is to consistently strive for a minimum of five sleep cycles or seven and a half hours of sleep every night, and definitely more than 28 sleep cycles per week. According to a recent Gallup poll, 40 percent of Americans get less than six hours of sleep per night, and are therefore operating in a constant sleep deficit — many endurance athletes are no different.

Athletes often worry about poor night’s sleep before a big event; however, research shows that neither endurance nor strength are significantly diminished with only one night of poor sleep. However, persistent poor sleep will lead to adverse effects on sports performance. 

Sleep deficit will result in a higher rate of perceived effort (RPE) and a decreased pain tolerance for equivalent workload compared to periods of normal sleep. Poor sleep also impairs the body’s ability to regulate temperature and will create problems for athletes with thermoregulation in hot temperatures as well as cold environments. Athletes who consistently sleep less than eight hours per night are 1.7 times more likely to sustain a training related injury compared to those who consistently sleep more than eight hours. 

While it may be discouraging how poor sleep can impact performance, sleep extension or correcting poor sleep can reverse some of the above decrements. As the goal is to accumulate 35 sleep cycles per week, or more for athletes with high training loads, catching up sleep on weekends can provide some aid in recovery and may mitigate some of he negative effects of poor sleep during the week. Catch-up sleep, however, only “repays” a partial amount of your sleep debt, and is not a perfect replacement for consistent high quality sleep.

Sleep hygiene and planning are the cornerstones for better sleep quality. Triathletes should put the same amount of planning and focus into their sleep as they do their training. Professional sleep coach Nick Littlehale recommends planning sleep in 90-minute cycles and working backwards, while starting bedtime routine 90 minutes before your scheduled or desired bedtime.

This time is used to start “winding down” and getting into your bedtime routine. It is important to try to go to sleep and wake up at the same times every day in order to ensure that your “body clock” stays tuned. The sleep environment should be cool, dark, and quiet. Screen time should be minimized in the 30-60 minutes prior to sleep. In fact, it is recommended that serious athletes leave their phones outside the bedroom to minimize disruptions. 

Athletes may look for pharmacologic means to aid sleep, but many of the prescription sleep medications can be addictive, habit forming and may lead to a “hangover” like effect in the morning. Also, at the highest levels of competition, sleep medication may be on the banned substance list. 

Melatonin is often cited as a natural aid that can increase the body’s melatonin level, which is one of the body’s signals to promote sleep. However, in our experience, the active level of melatonin is not reliably monitored in supplements and many athletes suffer from the adverse effects of vivid dreams, nausea and headaches, which limits their effectiveness. 

Consumption of 20 grams of casein protein before bed will decrease sleep latency (the time it takes to fall asleep) while also aiding muscle recovery. Tart cherry juice, when consumed twice daily over a minimum of two weeks, will improve sleep quality and quantity. Finally, magnesium supplementation of 250-500mg per night leads to improved sleep quality, quantity and decreases latency.

It is clear that sleep is an important factor in recovery from triathlon training. With the appropriate attention and planning, sleep can become an asset to recovery and performance instead of a liability. 

Dr. Chad Asplund is an Associate Professor of Health and Kinesiology and the Director of Athletic Medicine at Georgia Southern University. He received his MD from the University of Pittsburgh and then completed a family medicine residency at DeWitt Army Community Hospital in Fort Belvoir, Virginia. He has previously practiced family medicine in the Army, including a combat tour to Afghanistan. Following his obligation in the Army he completed a Sports Medicine fellowship at The Ohio State University and served as a team physician for the Buckeyes for two years.  He currently serves as Head Team Physician for the Georgia Southern Eagles. He is also the current President of the American Medical Society for Sports Medicine. 

Medical Editor Andrew Getzin, MD is the head team physician for USA triathlon. He is a USA Triathlon level I coach, multiple-time USA Triathlon All-American and has competed in Kona. He is a fellow of the American College of Sports Medicine. Dr. Getzin is the medical director of Cayuga Medical Center Sports Medicine and Athletic Performance in Ithaca, NY, www.cayugamed.org/sportsmedicine and the director of their shortness of breath in the athlete clinic, www.cayugamed.org/sob

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.


Resources and references

  • Littlehale N. Sleep: The Myth of 8 hours, the Power of Naps…and a New Plan to Recharge Your Body and Mind.  2016. Penguin UK.
  • Cauter EV and Plat L, Spontaneous growth hormone secretion and the diagnosis of growth hormone deficiency. J Pediatr 1996;128:S32-7
  • Watson AM, Sleep and Athletic Performance. Curr Sports Med Rep 2017;16(6):413-418