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Sleep is the natural recurring human activity by which we recover, rebuild, rest and digest. During sleep, your body is rejuvenating its entire system and as such is an essential process for the maintenance and improvement of your immune, nervous and skeletal systems as well as your musculature. As such, how well you sleep can affect not only performance of exercise related activity, but also functions we often take for granted, such as the ability to fight infection and carry out simple problem solving/memory tasks.
Sleep improves muscle building/recovery because during this time your body is in its prime anabolic (muscle building) state due to hormone fluctuations. Both testosterone and growth hormone (both muscle growth boosters) increase during sleep. Furthermore, without sleep, cortisol (the “stress” hormone) levels increase which decrease muscle building due to increased protein breakdown.
People who sleep less will also find it harder to stay lean. Research has shown that only one sleep deprived night can increase insulin resistance in healthy individuals [1], causing an increase in insulin (a fat storing hormone) which increases fat storage as a latent effect. In fact, if the average male slept an extra hour every day, he would stand to lose an extra 14.3lbs a year [2].
Chronic sleep deprivation has been found to decrease athletic performance in various sports, such as tennis, swimming and basketball [3,4,5,6] – sports which require varying levels of strength, agility and co-ordination. Again, this is believed to be due to the same hormone fluctuations as mentioned previously with regards to muscle building. Quite interestingly, acute sleep deprivation (zero sleep for 24 hours) was found to have no effect on strength/power performance (assessed using clean and jerk, snatch, etc) but the athletes were found to have very low moods, a lack of enthusiasm and increased confusion [7], making it highly likely that if they hadn’t been required to attend the gym for research purposes, you wouldn’t have found them there! Another study discovered that glucose metabolism was less efficient with sleep deprivation (related to insulin resistance) which meant athletes could not perform maximally due to a lack of energy.
Outside of sport and exercise, sleep deprivation has been found to increase mortality as a result of cardiovascular disease such as high blood pressure. In fact it was shown that those who sleep less than 6 hours a night are TWICE as likely to suffer a heart attack in their lifetime than those who receive 7 hours or more [8,9]. Another showed that sleep deprivation is also connected to breast cancer, increasing the chances by up to 200% [10]. Putting this information together, the sleepless among us are 20% more likely to have passed away in the next 20 years [11] than those who get adequate shut-eye.
Sleep has also been correlated with intelligence and personality. Children who sleep more have been found to have a higher IQ on average than their exhausted peers [12]. Not surprisingly, individuals who sleep more are “nicer” people, with research showing that they can show more empathy [13]...there’s an eye-opener for you – tired people are more grumpy...
Put simply – get more sleep! The question is, how much more? It is recommended that adults should sleep between 7-9 hours a night [14]. Over the course of a lifetime, the amount of sleep required to function actually decreases. To optimize your snoozing, you should try to approach sleep fully fed/watered having avoided stimulants such as caffeine, alcohol and nicotine for a period of 4-6 hours. Sleeping in as dark an environment as possible will also help provide a more productive sleep – cool colours such as blue or even dim white light will cause more trouble sleeping – either hide your phone from sight or change the colour!
If you are trying to sleep as described above and still can’t switch off, there are numerous “sleep hacks” to help you get yourself to sleep, for example the ever popular “Paradoxical Intention” method, where you close your eyes and try to stay awake. Skeptical? Try it. Serotonin (the “happy” hormone) promotes deep sleep –before going out and grabbing the pharmaceuticals, try watching Anchorman.
With all of the good news about sleep, could it be possible that you can get too much of a good thing? People who sleep more than 8 hours a day have been found to have a higher death rate than those who sleep only 6-7 [15], while correlations have been made between over-sleeping and depression, decreased energy levels/exercise, Seasonal Affective Disorder and poor diet. However, the research appears to be showing that it’s not sleep itself that causes these problems, but rather that the long sleep durations are caused by the issues themselves.
The take home message here is that sleep is not a static period of time – your body is going into overdrive to prepare you for the next day. Optimal sleep is not about sleeping as much as possible, but getting an adequate amount of deep sleep – think quality, not quantity. The health benefits of getting the right amount of down-time are vast and real and yours to keep for the price of simply lying down, closing your eyes and switching off. So next time you’re up at 1am doing “nothing” – try doing “something”.
Rated Strength and Conditioning Coach/Researcher Sean Cassidy has over a decade of competitive sporting experience in Athletics and Rowing where he has had success representing his country at an international level. He has coaching experience in Weight Lifting, Body Building, Rowing and Strength and Conditioning for both MMA and Rugby. He currently resides in Dundee, Scotland, where he coaches oarsmen/women at the Dundee University Boat Club as well as taking on personal training clients/athletes who wish to improve their abilities. Sean can be contacted at sean@commonstrength.com
References:
1. The Journal of Clinical Endocrinology and Metabolism (Donga et al. 95 (6): 2963) (June 2010)
2. The Obesity Revue 2006 (Sivak M. 7(3): 295-6)
3. Study Shows Sleep Extension Improves Athletic Performance and Mood. Annual Meeting of the Associated Professional Sleep Societies.( C. Mah)( June 8, 2009)
4. Extended Sleep and the Effects on Mood and Athletic Performance in Collegiate Swimmers. Annual Meeting of the Associated Professional Sleep Societies. (C. Mah )(June 9, 2008)
5. Extra Sleep Improves Athletes' Performance. Annual Meeting of the Associated Professional Sleep Societies. (C. Mah)(June 14, 2007)
6. Sleep, recovery, and performance: the new frontier in high-performance athletics. Phys Med Rehabil Clin N Am. (Samuels C . 20(1):149-59, ix)(February 2009)
7. Journal of Strength & Conditioning Research. (Blumert et al. 21(4):1146-1154) (November 2007)
8. Sleep duration as a risk factor for diabetes incidence in a large U.S. sample. Sleep 2007 (Gangwisch JE, Heymsfield SB, Baden-Albala B et al; 30 (12):1667-73)
9. Gender-specific associations of short sleep duration with prevalent incident hypertension: the Whitehall II Study. Hypertension 2007. (Cappuccio FP, Stranges S, Kandala N et al; 2007;50(4): 693-700)
10. Melatonin, sleep disturbance and cancer risk. Sleep Med Rev 2009 (Blask DE.; 13(4): 257-64)
11. Sleep and mortality: a population-based 22-year follow-up study. Sleep 2007 (Hublin C, Partinen M, Koskenvuo M, Kaprio J. 30:1245-53)
12. Short sleep duration is associated with poor performance on IQ measures in healthy school-age children. Sleep Med 2010;11. (Gruber R et al (3); 298-94)
13. Sleep deprivation impairs the accurate recognition of human emotions. Sleep 2010. (van der Helm E, Gujar N, Walker MP; 33(3):335-42)
14. Zeo Sleep Research Center DOZER database.
15. www.sleepwarrior.com
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