Intro: Sleep for Endurance Athletes

Sleep is THE MOST critical recovery-related aspect of endurance training and one of the most essential all-encompassing factors for endurance performance. Of course, endurance athletes should set themselves up for improvement with intelligent training, nutrition, and supplements. However, it is ONLY during sleep that most of the positive adaptations resulting from that daily effort are realized.  

No matter how often you hear silly sayings like – “sleep-less, train-more” or “while the competition is sleeping, I’m training,” the science is clear. As an endurance athlete, you need long and restful sleep to be your best. If you are training more in the sacrifice of adequate sleep, I’m sorry, but you’re not doing yourself any favors.

This blog will dive into what the scientific literature suggests are the best practices for endurance athletes regarding sleep. We will discuss optimal sleep duration, naps vs. sleep, sleep hygiene, and the various impacts sleep has on endurance training. We will build off a solid foundation of science in an effort to demystify topics surrounding adequate sleep for endurance athletes.  

The Tremendous Impact of Sleep for Endurance Athletes

Sleeps Impact on Endurance Recovery

Let’s start with what is likely the most fundamental reason why endurance athletes should aim for enough high-quality sleep – optimal endurance recovery. The impact that sleep has on endurance recovery is profound and for various reasons. Here are just a few processes that happen during sleep that are critical for endurance recovery;

• Human Growth Hormone (HGH) is released (highest during deep stages soon after falling asleep)
• Testosterone levels are at their highest (highest during REM in the later stages of sleep)
• Cortisol decreases
• Muscles and cells are repaired
• Organs rest and recover
• Memories are formed, and information is sorted and stored

And of course, there’s much more that goes on while you’re sleeping, but isn’t that enough? Much of the reason inadequate sleep negatively impacts endurance recovery is likely due to sleep’s significant impact on hormones and inflammation. Lack of sleep has been shown to have a negative effect on various hormones and inflammatory markers, including inflammatory cytokines, IGF-1, cortisol, and the cortisol/testosterone ratio (Dáttilo et al., 2020).

It’s clear that increased sleep significantly improves endurance recovery while inadequate sleep inhibits it. In endurance sports, optimal recovery is just as important as optimal training. If you’re an endurance athlete and you’re not recovering as well as you’d like, start with more sleep. 

Sleeps Impact on an Endurance Athlete’s Risk of Injury

Various studies show that sleep has a tremendous impact on an athlete’s chances of injury.  

A study on over 100 young athletes showed that athletes who obtained less than 8 hours of sleep/night were 1.7 times more likely to suffer an injury than those who slept 8 hours or more (Milewski et al., 2014).  

Another study on collegiate-level male basketball players also concluded that increased sleep significantly reduced an athlete’s risk of injury during the season while also improving mood and well-being (Watson et al., 2020).  

There are a few different theories on why sleep has such a tremendous impact on injury prevention, and it’s likely a combination of them all.  

It could be that without adequate sleep, an athlete never sufficiently recovers from daily exercise. Reaction time and awareness are also impaired when sleep-deprived. A quick reaction can often be the difference between getting injured and staying healthy, even in endurance sports. Think of a trail-runner who is constantly scanning a rugged, rocky, root-filled trail and determining a safe place for his next step to land. Or an endurance cyclist flying downhill at ridiculous speeds – when risk is high, concentration and reaction times are critical for preventing catastrophe.

Whatever the reason for the increased injury rate that comes with insufficient sleep, it’s clear that adequate sleep for endurance athletes is a significant factor in preventing it.

Sleeps impact on Recovery from Injury

Not only does sleep prevent injuries, but it also heals them. During sleep, the body repairs damaged (and builds new) tissues. There is no other time when the body does so as efficiently as when asleep. Injuries, unfortunately, are quite common in endurance sports, and most seasoned endurance athletes have suffered an injury at some point in their careers.   

Undoubtedly, rest, nutrition, compression, inflammation management, and various other factors are essential when recovering from an injury as quickly as possible. Sleep is an essential and massive piece of this puzzle.  

Endurance athletes often acquire less sleep when injured because training volume is significantly reduced. They might not feel as exhausted, leading them to believe they don’t need as much sleep.

On the contrary, endurance athletes should aim to acquire additional sleep when injured.  For more information on why sleep is essential for recovery from exercise and injury, check out https://www.orthocarolina.com/media/sleep-the-secret-ingredient-of-injury-recovery

Sleeps Impact on Endurance Performance

Stanford University has produced tremendous studies highlighting the impact of sleep on athletic performance. Although not specifically endurance-related, the studies have displayed an immense performance benefit to sleeping more than 8 hours/night. College basketball players who stayed in bed for 10 hours/night ran faster, shot free throws and three-pointers with over 9% improved accuracy, all while improving their mood and feelings of well-being (Mah et al., 2011).  

Another study, more relevant to endurance sports, shows that sleep deprivation decreases time to exhaustion (Azboy & Kaygisiz, 2009). As we all know, time to exhaustion is a central measurement and an influential performance attribute in endurance sports.  

If optimal performance is desired, sleeping more than what is thought of as “typical” is necessary.  

Sleeps Impact on Immunity

Endurance athletes are more likely to catch a cold, an upper respiratory infection, or another illness during times of heavy training. Sleep is hands-down the best defense against an illness for endurance athletes. That’s right, it isn’t vitamin C, it isn’t cold showers or supplements, it’s sleep. Without adequate sleep, those other things don’t mean that much; they’re a “Band-Aid” for a much larger problem.  

A study by Cohen et al. (2009) suggests that missing just one hour (7 hours vs. 8 hours) of sleep/night for 2 weeks increases the chances of contracting a cold by about 300%! Struggling with staying healthy during heavy endurance training? Start with more sleep!!!

Adequate sleep for endurance athletes is the single best way to prevent illness and infection during heavy training.

Useful Information on Sleep for Endurance Athletes

Sleep Cycles

During sleep, we go through sleep “cycles” that typically last around 1.5 hours/cycle. Most of our time in bed consists of light sleep. Light sleep is an essential piece of the sleep puzzle in that it holds the key to all other stages of sleep. It is the first step in getting a good night’s sleep.

Check out the chart below to see what a typical night’s sleep might look like. Then we will highlight a couple of stages of sleep that are of particular importance for endurance athletes.

 

Deep Sleep (Slow-wave sleep)

This is the period where HGH (human growth hormone) is released.  Human growth hormone is essential for protein synthesis and creating positive adaptation and growth (muscle building) from endurance exercise.  As you can see from the chart above, stage 3-4 slow-wave sleep happens early after the onset of sleep and decreases every sleep cycle.  Slow-wave sleep often isn’t present at all in later stages of sleep.

To maximize deep sleep an endurance athlete should aim to go to bed at close to the same time every night.  Going to bed significantly later than “normal” bedtime can cause an athlete to miss the opportunity for their longest session of deep sleep.  As a result, less HGH is released and muscles do not optimally adapt to endurance exercise.

Slow-wave sleep should account for about 15-25% of sleep, the equivalent of 1-2 hours for most people.

REM Sleep

REM (Rapid Eye Movement) sleep is one of the most critical stages of sleep for endurance athletes.  During REM sleep testosterone release is at its highest, information is processed, and tissue and cell repair are taking place.  REM sleep usually doesn’t come on until about 1-1.5 hours after the onset of sleep.  Additionally, REM duration increases every sleep cycle.  So the longer you sleep, the more cycles you will go through, and the more cycles you go through, the longer the REM phase lasts (see chart).  You can see why sleeping one more sleep cycle (or one less) has a massive impact on an endurance athlete, for better or worse.

1.5 – 2.5 hours of REM sleep is necessary for optimal recovery.  As an endurance athlete, if you’re getting less than 1.5 hours of REM sleep/night you should increase your duration of sleep.

How do I track my sleep cycles?

There are a plethora of simple ways to track your sleep these days.  Most high-tech smartwatches will track your sleep and there are also various smartphone apps like SleepScore that do a great job as well.

Naps vs. Sleep for Endurance Athletes

As I mentioned earlier, REM sleep is critical for endurance adaptation and recovery. Napping will not get you to the highly restorative stages like REM sleep and typically won’t get you into deep sleep either. 

Therefore, napping is NOT an adequate replacement for a good night’s sleep. However, napping can be used strategically to get yourself over a hump or a midday lull.  

Keep the naps shorter than 25 minutes to avoid sleep inertia (grogginess upon wakening) and not disrupt your ability to fall asleep at night.* Remember, naps do not make up for a loss in extended sleep.

*If not less than 25 minutes, naps should be for an entire sleep cycle (about 1.5 – 2 hours) to avoid sleep inertia. However, as mentioned previously, this could negatively impact your ability to fall asleep at night.

How Many Hours of Sleep for Endurance Athletes?  

An endurance athlete should aim for at least 8 hours of sleep/night and 9 hours is better (Vitale et al., 2019). The recommendation for the average individual is 7-9 hours/night. 

But endurance athletes are not average individuals. The demand for recovery and rest is significantly amplified for endurance athletes and 6 and even 7 hours is insufficient for optimal recovery and adaptation. During heavy training, 9 or even 10 hours is best.

*Deena Kastor, one of the most decorated American runners of all time, has said that she sleeps 10 hours every night and takes a 2-hour nap most afternoons. Other elite endurance athletes follow similar molds. While this is likely impractical for all but full-time professional athletes, sleeping more is inarguably a tremendous advantage for peak endurance performance.

Sleep Hygiene for Endurance Athletes

Keep it Cool and Dark 

Make sure your bedroom is nice and cool. Cool temperatures and darkness prime your body for sleep and increase the release of melatonin. If you go to bed when it’s still light out, use blackout curtains.

Phone Screens / Blue Light / TV

Most people know by now that using electronic devices that put off blue light before bed is a bad idea. 

Obviously, these things negatively impact both onset of sleep AND the quality of sleep. But how much? And how long before should someone unplug to not screw up their sleep quality?

Using blue light-emitting devices before bed (TV, laptop, phone, etc.) can shift your circadian rhythm by 3 hours. This shift negatively impacts melatonin production and results in reduced sleep quality. Studies suggest that blue light exposure can have a negative impact on melatonin and sleep quality even as far as four hours before bed (Wahl et al., 2019). The closer it is to bed, the sleep quality will likely be impacted.

Cutting out all blue light four hours before bed might not be possible for all endurance athletes. Aim to eliminate blue light within 2 hours of bed. 

Additionally, blue-light-blocking glasses could be worn within 4 hours of bed (if necessary) to reduce the magnitude of exposure.

Eating Before bed

Some suggest not eating before bed because of a potential negative impact on sleep. Studies show, however, that athletes can benefit from protein immediately before bed as it can increase muscle protein synthesis during sleep. 

I’d recommend a protein shake before bed. Minimize fat, fiber, and excessive carbs directly before bed as these can slow digestion and disrupt sleep quality. A protein shake is likely beneficial for endurance athletes to take before bed on training days and should have minimal impact on sleep quality.

Lay Off Alcohol Before bed

Alcohol has a negative impact on sleep quality. If you’re going to enjoy a drink or two, doing so as far away from bedtime is best. For tons of information on alcohol and how it affects endurance athletes, you need to check out Alcohol and Ultra-Running: Match Made in Heaven, or Recipe for Subpar Performance?

Have a Nighttime Routine

Having a routine will tell your body it’s time to wind down and get ready to sleep. Try to go to bed (and get up) close to the same time every day. 

Wind down with a book (paper, of course), meditating, light stretching, or any activity that promotes relaxation. Don’t try to cram stressful work into the last couple of hours before bedtime.

Summary of Sleep for Endurance Athletes

As you can see, there is little an endurance athlete can do that will have as profound of an impact on their overall performance as that of sleep. Sleep literally influences every other aspect of endurance training and recovery. It not only is a critical piece of the endurance puzzle, but it’s also a piece that impacts every other piece! Whether that impact is positive or negative is up to the athlete. Hopefully, this blog has helped you, as an endurance athlete, determine steps to take to positively impact your sleep and endurance performance.

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