When people talk about recovering from exercise, they usually talk about foam rolling, stretching, supplement choice, and diet. They may also look at hydration, but that’s rare.
In this article we are going to look at five evidence based reasons why sleep can help you recover from intense exercise sessions.
One thing that we should make clear before going ahead with this article is what we mean by a benefit of sleep. Because this is slightly different to say the benefits of taking whey protein, or the benefits of exercise.
When we talk about a benefit of sleep, we can either be discussing something good that occurs after lots of sleep, or something bad that occurs after a bad night’s sleep.
So a benefit in this scenario would be the avoidance of the negative effects of sleep. As an example, a bad night’s sleep can lead to overeating due to an increase in Ghrelin and a decrease in Leptin . But by sleeping well for eight hours you will avoid this issue, therefore it would be accurate to say that one benefit of sleeping well is a reduced risk of overeating.
Here is a list of five reasons why a good night’s sleep can help to optimise recovery, as mentioned above most of these are beneficial in that they prevent negative effects of bad sleep. But we will point this out as we go along.
Testosterone is a sex hormone that is integral to muscle building after exercise, it is partly down to a lack of testosterone that most women are never able to develop anywhere near as much muscle as men. So having more testosterone is correlated with being able to build more muscle.
Studies have shown that the amount of sleep you get each night can have an effect on your testosterone levels. A study by Goh & Tong (2010) looked at how sleep affected Asian men’s testosterone levels, it found that the less sleep you had the lower your testosterone levels would be . By sleeping more you can reverse this loss of testosterone, and therefore you will be able to build muscle better, and recover from exercise.
Human Growth Hormone (HGH) is a fantastic hormone for muscle building (which is why it is so often taken illegally as a performance enhancer). It is amazing for recovery as it can not only help stimulate protein synthesis, but it can also help to speed up muscle repair.
If you were to become injured, higher levels of HGH would help to fix fractured bones faster. Studies have shown that sleeping more can increase levels of human growth hormone as it is during sleep that HGH is maximally released .
Another benefit of increased HGH is that it can improve sleep quality! So you have a nice relationship there, where more sleep increases HGH which in turn improves sleep quality further.
As we have mentioned before, it is at rest that protein synthesis works best, but this is not the only way that protein synthesis can be increased. Taking more protein can also help as it increases the net protein balance (which can be affected by exercise).
What’s interesting is that taking a protein shake (specifically a Casein protein shake) just before bed time has been shown to be even more effective than taking it at a different time of the day. A study by Res et al (2012) found that protein ingestion just before sleep helped increase recovery . Casein can also help you to sleep better, which makes this a perfect combination for recovery.
Cortisol is a hormone that is produced in the adrenal gland, when you are stressed cortisol is released. It has many benefits, and is integral in the metabolism of macronutrients. But in high levels cortisol can lead to long term weight gain and obesity, and (more relevantly for this article) it can hinder muscle growth and recovery.
This is because cortisol works in the opposite way to testosterone, it catabolises muscles, reduces protein synthesis, and can inhibit tissue growth. When properly controlled these functions can be beneficial, it is only when you are suffering from chronically high cortisol that it becomes an issue.
Luckily sleep has been shown to indirectly reduce cortisol. Remember that cortisol is usually released as a response to stress, well sleeping more can help to improve mood, reduce stress, and increase cognitive function, which can all lead to reduced cortisol production. A 2007 study by Mah, Mah, & Dement found that sleeping for prolonged periods of time improved mood in college athletes .
On the flip side, a lack of sleep can lead to elevated cortisol levels the next day – which can inhibit muscle growth, and further affect sleep the next day. Leading to poor recovery from a workout .
If you train regularly (every day) then you need to start thinking about continued recovery over a very long period of time. What you want to avoid is diminishing performances in the gym. If instead of the gym you are participating in sports that take place over multiple days (5 day cricket test matches, 3-4 day golf matches, tennis tournaments, athletic events etc), then you probably need to be performing at 100% for quite a few days in a row.
This is where sleeping more than you would usually (8-10 hours) can really help. A famous study by Mah et al (2008) found that swimmers who slept for prolonged periods of time performed better the next day. They had improved reaction times, improved focus, increased power, and agility .
As you can see sleep is an integral part of recovery, potentially the most important part. It can improve your hormonal regulation, improve mood, improve cognition, improve performance, and it has a huge effect on muscle protein synthesis. It is for this reason that many professional sports teams and players have really started to concentrate on sleep as another edge over their competition.
In this BBC article  we learn that Real Madrid, Manchester United, and Manchester City have all spent fortunes trying to create the perfect sleeping environments for their athletes. And that stars such as Lebron James and Roger Federer sleep over 10 hours per night. If you are looking to get the most out of your gym time then sleeping a few more hours each night is a great place to start.
References Taheri, S., Lin, L., Austin, D., Young, T., Mignot, E. 2004. Short sleep duration is associated with reduced Leptin, elevated Ghrelin, and increased body mass index.PLoS1(3): e62  Goh, V. Tong, T. 2010, Sleep, sex steroid hormones, sexual activities, and ageing in Asian men. Journal of Andology31(2): 131-7  Born, J., Fehm, H. 2000. The neuroendocrine recovery function of sleep. Noise Health2(7): 25-37  Res, P., Groen, B., Pennings, B., Beelen, M., Wallis, G., Gijsen, A., Senden, J., Van loon, L. 2012. Protein ingestion before sleep improves post-exercise overnight recovery. Medicine & Science in Sports & Exercise44(8): 1560-9  Mah, C., Mah, K., Dement, W. 2007. The Effects of Extra Sleep on Mood and Athletic Performance amongst Collegiate Athletes. Sleep30[suppl]  Leproult, R., Copinschi, G., Buxton, O., Van Cauter, E. 1997. Sleep loss results in an elevation of cortisol levels the next evening. Sleep 20(10): 865-70  Mah, C., Mah, K., Dement, W. 2008. Extended Sleep and the Effects on Mood and Athletic Performance in Collegiate Swimmers. Sleep31[Suppl]  http://www.bbc.co.uk/sport/football/32276547
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