Think sleep is about little else than simply resetting your brain? Think again. Sleep is a very active recovery process that you don’t want to miss.
We all love sleep and far too many of us don’t get enough of it. It’s easy to see how sleep does a fantastic job of refreshing our brains, helping us be rational and not emotional, and giving us energy to take on the day.
To scientists and physicians, sleep has always been quite mysterious. Over the last 20-30 years, however, much more research has been done on sleep and we are discovering its myriad functions.
Not only does sleep help us learn better and prevent diseases like Alzheimer’s, it has many functions that effect our physical performance and can actually help you train better and become stronger.
1. More Effort = More Gains
When you get little sleep, studies show that you put in less effort into your tasks. On top of that, the studies show that you don’t even recognize that decrease in effort. (Engle-Friedman et al., 2003)
So when you get little sleep, you don’t work as hard and you don’t even know it.
Since strength and muscle growth is directly related to how much effort you put in at the gym, getting more sleep will help you push yourself to your true max effort and gains.
2. Increased Protein Synthesis and Growth Hormones
Human growth hormone (HGH) plays a key role in building muscle and strength. Unless you’d like to go the route of supplementing with steroids, the best way to naturally produce more HGH is by sleeping more.
Studies have shown that throughout the 24-hour day, the body produces the highest levels of HGH during REM sleep (Parker et al., 1980; Sassin et al, 1969).
The amount of REM sleep you get depends on the length of time you sleep at night. Early on the night, your sleep cycles contain longer periods of deep sleep and shorter periods of REM sleep. But later on the in night, your sleep cycles contain much longer periods of REM sleep (Hoffmann, 2013).
That means getting slightly more sleep every night gives you proportionally much higher amounts of REM sleep.
That’s under normal sleep conditions. Under conditions of sleep deprivation (< 6 hours per night), your body prioritizes other phases of the sleep cycle more than REM sleep so you’re going to get even less REM sleep.
On top of that, when you start getting adequate sleep after a period of sleep deprivation, your body goes through a recovery phase of 2-3 nights where it still prioritizes the other sleep cycles over REM sleep (Carlson, 1999). Meaning, you need to be getting plenty of sleep, and plenty of sleep regularly, to get the full growth hormone and protein synthesis effects of REM sleep.
3. Less Cortisol Means Less Muscle Breakdown
Sleep deprivation, especially chronic sleep deprivation, has been shown in multiple studies to lead to higher baseline cortisol levels (Wright, 2015; Mougin, 2001). Cortisol is commonly known as “the stress hormone” and puts you in a more catabolic state of muscle breakdown.
Contrary to popular “Bro Science”, your body is always at the same time both catabolic and anabolic. Your body is always breaking down some tissue for energy and repair and building other tissue up. The terms “catabolic state” and “anabolic state” aren’t absolute but are on a continuum related to the balance of how much tissue is being broken down and how much is being built.
Returning to an adequate amount of sleep every night decreases your baseline cortisol level and decreases the amount your body feels it needs to breakdown tissue for stress resources and therefore puts you in a more anabolic state (Wright, 2015; Mougin, 2001).
4. More Neurotransmitters → More Strength
The way your muscles know to move is your brain sends signals to them through your nerves. Where your nerves connect to each other and where your nerves connect to the muscle, the signal gets transmitted by molecules called neurotransmitters.
Over the day, the neurotransmitters break down and get stuck and are overall less able to send their signals.
During sleep, your body has been shown to replenish those neurotransmitters both in your brain and at the junction where the nerves meet the muscle (Hobson, 1995).
With more sleep, your body is able to have more effective junctions between the nerve and the muscle and so you are able to lift more weight and build more strength.
5. More Reps to Failure
Sleep deprivation, especially chronic sleep deprivation, has been shown to cause decreased pain tolerance (Haack, 2009; Haack, 2005, Haack, 2007).
I wrote previously about how training to failure or very close to failure has been shown to lead to maximum strength gain. Training to failure is often dictated by the amount of pain we are willing to tolerate. Once the pain is intolerable, that is the point of failure, and that is where muscle growth is maximized (and muscle injury is avoided).
However, if our pain tolerance is decreased by sleep deprivation, we will reach that maximum amount of pain earlier than necessary. Then we won’t get in as many reps, and won’t gain as much as we are capable.
6. Fewer Distractions
It is extensively studied and well documented that chronic sleep deprivation is associated with symptoms of depression and anxiety. (Aikens & Mendelsen, 1999; Monroe, 1967; Zammit, 1988)
While it can be hard to differentiate which comes first, one study (Zammit, 1988) showed that in adults without anxiety or depression, intentionally decreasing amount of sleep during the study period caused them to have many more symptoms of anxiety and depression.
When you feel depressed and anxious, you have a much harder time getting yourself to the gym in the first place and then working your hardest when at the gym.
The study by Zammit suggests that even if you don’t have a clinical diagnosis of anxiety or depression, lack of sleep can give you some of the symptoms. And on the contrary, increasing your amount of sleep can resolve these symptoms, getting you into the gym easier and working harder while there.
7. Eat Less Unhealthy Food
Multiple studies have shown that < 8 hours of sleep nightly can cause changes in hormones that cause you to eat more and crave the unhealthiest foods while you’re at it (Morselli, 2010; Prinz, 2004; Spiegel, Tasali, Penev, & Van Cauter, 2004; Taheri et al., 2004).
Spiegel and colleagues (2004) found that decreasing sleep to < 8 hours in otherwise healthy, normal weight men caused increased levels of a hormone ghrelin that stimulates appetite and fat production and decreased levels of a hormone leptin that suppresses appetite and increases energy levels. These men all gained a significant amount of weight during the study whose only intervention was decreasing their amount of sleep nightly.
8. Prevents Acute Illness
There have been a few very interesting studies showing sleep deprivation with no other lifestyle changes, causes a 50% decrease in “natural killer T cells” [19,20]. “Natural killer T cells” are the cells in your immune system whose primary responsibility is fighting off viruses, particularly cold and flu viruses.
While it’s a good idea to maintain mild-moderate activity while you have a cold or flu (such as walking, chill yoga, or doing 30-50% of your normal lifting routine), you should not be training hard.
So with more time on the bench with a cold, the less training you get in. Getting extra sleep ensures that you spend the minimum time possible out with a cold and therefore maximize your gains.
9. Prevents Chronic Illness
A large amount of scientific literature has shown a correlation between little sleep and worse chronic disease, particularly cardiovascular diseases like high cholesterol, high blood pressure, and heart disease as well as glucose intolerance (or early diabetes) (Ayas et al., 2003; Gottlieb et al., 2005; Patel et al., 2004; Lee & Lin, 2007; Bonnet & Arand, 1998; Asplund, 2000; Newman, Enright, Manolio, & Haponik, 1997; Appels & Mulder, 1984) [21-28].
All of these chronic diseases make it more difficult for your body to exercise and perform strenuous tasks. They also make it much more difficult to recover properly to build strength.
The problem with these studies is that there are likely many other poor lifestyle choices and factors associated with those that get such little sleep (such as high stress, poor diet, low income, no time to exercise or access to fitness equipment). None of them found a way to completely control for these other factors. Since sleep has so many restorative and anabolic functions, it’s very likely that sleep deprivation is a major contributing factor since it correlates so well.
Therefore getting adequate sleep is another weapon in your toolbox fighting chronic lifestyle disease.
So there you are: 9 very compelling reasons to go to bed early or find a way to sleep in a bit more. For all of these reasons, sleeping more will literally make you stronger, without you having to change anything else.
Sleep hygiene is crucial to maximizing returns from sleep so be sure to check out my post on 25 Sleep Hygiene Tips to Dominate Your Fitness Goals.
Dr. Elle, MD
- Engle-Friedman, M., Riela, S., Golan, R., Ventuneac, A., Davis, C., Jefferson, A., & Major, D. (2003). The effect of sleep loss on next day effort. Journal of Sleep Research, 12, 113-124.
- Parker, D. C., Rossman, L., Kripke, D. F. et al. (1980). Endocrine rhythms across sleep wake cycles in normal young men under basal state conditions. In: Orem, J., Barnes, C. D. eds. Physiology in Sleep. New York: Academic Press.
- Sassin, J. F., Parker, D. C., Johnson, L. C., Rossman, L. G., Mace, J. W., Gotlin, R. W. (1969). Effects of slow wave sleep deprivation on human growth hormone release in sleep: Preliminary study. Life Science, 8(23), 1299-1307.
- Hoffmann, R.M. (2013). The relationships of sleep quality, length, and napping to physical performance. Louisiana Tech Digital Commons.
- Carlson, N. R. (1999). Foundations o f Physiological Psychology (4th Ed.). Needham Heights, MA: Allyn & Bacon.
- Wright KP Jr, Drake AL, Frey DJ, Fleshner M, Desouza CA, Gronfier C, Czeisler CA. (2015) Influence of sleep deprivation and circadian misalignment on cortisol, inflammatory markers, and cytokine balance. Brain Behav Immun; 47: 24–34 [PubMed: 25640603]
- Mougin F, Bourdin H, Simon-Rigaud ML, Nguyen Nhu U, Kantelip JP, Davenne D. (2001) Hormonal responses to exercise after partial sleep deprivation and after hypnotic drug-induced sleep. J Sports Sci; 19: 89–97 [PubMed: 11217014]
- Hobson, J. A. (1995). Sleep. New York: Scientific American Library.
- Haack M, Lee E, Cohen DA, Mullington JM. Activation of the prostaglandin system in response to sleep loss in healthy humans: Potential mediator of increased spontaneous pain. Pain 2009; 145: 136–141 [PubMed: 19560866]
- Haack M, Mullington JM. Sustained sleep restriction reduces emotional and physical well-being. Pain 2005; 119: 56–64 [PubMed: 16297554]
- Haack M, Sanchez E, Mullington JM. Elevated inflammatory markers in response to prolonged sleep restriction are associated with increased pain experience in healthy volunteers. Sleep 2007; 30: 1145–1152 [PubMed: 17910386]
- Aikens, J. E., & Mendelson, W. B. (1999). A matched comparison of MMPI responses in patients with primary snoring or obstructive sleep apnea. Sleep 22(3), 355-359.
- Monroe, L. (1967). Psychological and physiological differences between good and poor sleepers. Journal o fAbnormal Psychology, 72, 255-264.
- Zammit, G. K. (1988). Subjective ratings of the characteristics and sequelae of good and poor sleep in normal adults. Journal o f Clinical Psychology, 44, 123-130.
- Morselli L, Leproult R, Balbo M, Spiegel K. Role of sleep duration in the regulation of glucose metabolism and appetite. Best Pract Res Clin Endocrinol Metab 2010; 24: 687–702 [PubMed: 21112019]
- Prinz, P. (2004). Sleep, appetite, and obesity-What is the link? Public Library of Science and Medicine, 1, 186-188.
- Spiegel, K., Tasali, E., Penev, P., & Van Cauter, E. (2004). Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine, 141(11), 846-850.
- 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. PLoS Medicine, 1(3), 62.
- Irwin, M., Mascovich, A., Gillin, J. C., Willoughby, R., Pike, J., & Smith, T. L. (1994). Partial sleep deprivation reduces natural killer cell activity in humans. Psychosomatic Medicine, 56(6), 493-498.
- Irwin, M., McClintick, J., Costlow, C., Fortner, M., White, J., & Gillin, J. C. (1996). Partial night sleep deprivation reduces natural killer and cellular immune responses in humans. The Journal of the Federation of American Societies for Experimental Biology, 10, 643-653.
- Ayas, N. T., White, D. P., Manson, J. E., Stampfer, M. J., Speizer, F. E., Malhotra, A., & Hu, F. B. (2003). A prospective study of sleep duration and coronary heart disease in women. Archives o f Internal Medicine, 163(2), 205-209.
- Gottlieb, D. J., Punjabi, N. M., Newman, A. B., Resnick, H. E., Redline, S., Baldwin, C. M., Nieto, F. J. (2005). Association of sleep time with diabetes mellitus and impaired glucose tolerance. Archives of Internal Medicine, 765(8), 863-867.
- Patel, S. R., Ayas, N. T., Malhotra, M. R., White, D. P., Shemhammer, E. S., Speizer, F. E., Stampfer, F. E., Hu, F. B. (2004). A prospective study of sleep duration and mortality risk in women. Sleep, 27(3), 440-4.
- Lee, A.J., & Lin, W.H. (2007). Association between sleep quality and physical fitness in female young adults. The Journal of sports medicine and physical fitness, 47 4, 462-7 .
- Bonnet, M. H., & Arand, D. L. (1998). Sleepiness as measured by the MSLT varies as a function of preceding activity. Sleep, 21,477-483.
- Asplund, R. (2000). Sleep, health, and visual impairment in the elderly. Archives of Gerontology and Geriatrics, 30(1), 7-15.
- Newman, A. B., Enright, P. L., Manolio, T. A., & Haponik, E. F. (1997). Sleep disturbance, psychosocial correlates, and cardiovascular disease in 5201 older adults: The Cardiovascular Health Study. Journal o f the American Geriatrics Society, 45(1), 1-7.
- Appels, A., & Mulder, P. (1984). Imminent myocardial infarction: A psychological study. Journal o f Human Stress, 10, 129-134.