Shortchanging yourself on sleep will slow your progress in the gym, inhibit your strength, and make you more prone to injury.

Want to learn why? You’re in the right place. 👌

In this article we’ll cover:

• Whether you can gain muscle on six hours of sleep.
• Sleep's role in muscle growth.
• How many hours of sleep you really need to build muscle.
• The consequences of lack of sleep.

Let’s get to it. 👇

Can you gain muscle with 6 hours of sleep?

Yes, you can gain muscle with just six hours of sleep, but you’re going to hinder your rate of progress massively if you make it a habit. What’s more, how much muscle you gain, and whether or not you manage to hold onto it, is another matter.

If you’ve never trained before, you’re in the enviable position of being primed for the renowned “newbie gains” phase, where you’ll grow pretty much whatever you do. This is true regardless of your age.

But your body’s only primed like this once. 🤯

Make the most of it, and you’ll transform your body in a matter of months. Waste this opportunity and others will leave you in the dust.

Intermediate and advanced gym-goers need to coax their bodies more carefully into responding to the training stimulus. Progress comes more slowly as it becomes more difficult to force your body to adapt. For these individuals, the answer is a bit more complicated.

Your age plays a part

Let’s consider your age. Testosterone levels peak in your 20’s and 30’s, with serum concentrations beginning to decline about 1% per year after that. (1) More recent studies, too, have reported that 10-15% of middle-aged and elderly men’s testosterone levels sit below the lower limit of the normal range. (1)

That’s a result of a myriad of factors, including the increase in sex hormone binding globulin (SHBG) with age. Reach 45, and it’s safe to bet your testosterone levels have already declined at least 10% from their peak, and will only decline further from there.

Since your testosterone levels affect how well your body responds to resistance training, older individuals with lower testosterone levels have a smaller margin for error when it comes to their efforts in the gym. You’ll have to be stricter with other aspects of recovery. That includes sleep.

For that reason, six hours of sleep may well not be enough for older individuals to make significant progress past the newbie gains phase.

Your genetic recovery capacity

Different people respond differently to the same amount of work in the gym. When it comes to volume, there’s a sweet spot. A muscle needs enough volume to trigger an adaptive response, but not so much it can’t recover before the next time the tissue is trained.

Too much work, performed too frequently, doesn’t give your body the time it needs to recover and supercompensate. The consequence? Slowed or stalled muscle growth. 😭

But recovery capacity isn’t entirely down to genetics. There are factors you can control. When you control them carefully, and optimize each one, you improve your body’s ability to recover. When you recover from more work more quickly, you can:

1. More maximally stimulate the muscle tissue you’re training in a given session.
2. Recover faster from that work, and so train that tissue again sooner.

This means you can go through more iterations of the “stimulate, grow, stimulate, grow” cycle in any given unit of time - a year, let’s say. Even better, any given cycle will be more potent, because you’ve stimulated that tissue more, triggering a greater adaptive response.

Lifestyle recovery factors you control

So, some can afford to drop the ball on their recovery more than others can thanks to their natural-born talent. Don’t be too envious, though - they’re shortchanging themselves, and could look even better if they adjusted for these other recovery factors.

These recovery factors are:

• Sleep
• Stress
• Hydration
• Nutrition
• Supplementation

Six hours of sleep isn’t optimal, but if you’ve got every other factor dialed in, it stands to reason you’d have a larger margin for error than the next guy who doesn’t. Unfortunately, since how long and how well you sleep determines a large part of how well you respond to stress, especially if you’re a busy, time-starved business owner or executive, a lack of sleep often proves carries its negative effects over into the other factors, too.

Sleep’s role in muscle growth

Sleep’s role in muscle growth is multifaceted.

First, there’s hormones. When you sleep, your pituitary gland floods the body with human growth hormone (HGH). At the same time, cortisol decreases.

When cortisol is high, testosterone predictably decreases. (2) Sleep flushes out higher concentrations of this catabolic hormone and promotes production of testosterone, which is one of the main components of a pro-muscle building environment in the body.

Better, longer sleep therefore shifts your body towards a favorable state for muscle protein synthesis (MPS), creating a bodily environment that supports muscle growth long-term.

Second, there’s performance. As we’ll discuss in a minute, longer sleep durations (up to 10 hours, in studies), (3) are shown to improve muscular co-ordination and athletic performance. This has implications for your ability to maximally stimulate muscle fibers in the gym. With higher peak voluntary contractions comes a greater muscle building stimulus.

A lack of sleep, on the other hand, has the opposite effect. Researches found fewer than eight hours of sleep (and especially fewer than six) reduced “limb extension force” and vertical jump height in study participants. (4) It also impaired the cardiovascular system in several ways.

What this means for your workouts, is that a lack of sleep impairs physical performance. If this is down to your body being less able to recruit all available muscle fibers, then the muscle-building effect of your workout will be negligible.

“The ability to maximally recruit all available fibers in a given motor unit pool is essential for maximizing the hypertrophic response to resistance training.” (5)

These studies suggests that, when sleep deprived, progress isn’t guaranteed at all. In fact, the less sleep you get, the smaller the stimulus from your workout will become. You’d be better off catching up on sleep instead. 😴

Third, there’s recovery. As discussed, once stimulated your body needs to be able to recover from the stimulus and supercompensate. Handily, another of sleep’s blessings is its effect on recovery after you’ve worked out.

Research demonstrates that sleep after physical activity makes your body recover faster. (6) Sleep soothes inflammation, stimulates muscle repair, and helps the processes that refuel your muscles with glycogen. When you recover faster and more effectively, you’ll notice faster gains in both your strength and your muscle mass.

So, missing sleep the night after working out has a clear, negative impact on your body’s ability to recover from resistance training.

So, of the two elements of our hypertrophic cycle (stimulate, recover, stimulate, recover), lack of sleep negatively impacts them both. You’re less able to recruit all available muscle fibers to stimulate them, but you’re also recovering more slowly.

Lack of sleep, then, will slow, or even halt, your muscle building progress. If you’re looking to get the greatest return on investment for time and effort spent in the gym (which you should), it makes no sense to not prioritize sleep.

But how does working out on a lack of sleep actually affect your ability to build muscle? 🤔

How many hours of sleep do you need to build muscle?

Ok, so sleep’s pretty important, but how much do you actually need?

Most experts recommend seven to nine hours. Conventional wisdom and common sense would say the same.

Remember, though, that you’re already pushing your body’s recovery requirements. The average person isn’t pushing the envelope in the gym, and they still need a minimum of seven hours.

The average person is largely sedentary. Perhaps they walk the dog twice a day. If that person needs seven hours, it stands to reason you’ll require more than seven hours when you add in the recovery demands of intense training.

For that reason, it’s safer to assume someone working hard in the gym needs closer to eight hours. Athletes training every day, or multiple time a day, might require even more. 🤔 👇

The Stanford Sleep Studies 🏊‍♀️

The Stanford Sleep Studies had a number of athletes from various sports sleep a mandatory 10 hours per night for between five and eight weeks. (3)

The results were shockingly impressive, both in terms of accuracy (tennis players hit 15.6 valid serves, on average, versus 12.6 at baseline), and speed (swimmers improved their times for a 15-meter sprint by more than half a second). Football players were faster in the 40-yard dash by a tenth of a second. Basketball players ran a 282-foot shuttle 0.7 seconds faster.

Swimmers sleeping ten hours per night improved 15-meter sprint times by more than half a second.

These increases in performance are important.

Our primary measure (and method) of building muscle is progressive overload - your ability to lift more weight for more reps over time. That requires exposing your body to a stimulus and allowing it to recover, then supercompensate (get better than it was before by growing new muscle tissue).

The test of whether your body has supercompensated is your ability to lift more load for more reps, which also exposes your body to a new stimulus, to which it must now adapt, starting the cycle again.

If more sleep means larger jumps in athletic performance, that means more supercompensation, and greater leaps in progress over time. In other words, to build the most muscle possible in the shortest period of time, you should get as much sleep as your schedule allows.

Should I workout if I only slept 6 hours?

Sure, it’s important to bear in mind what’s ideal when thinking about your training, but we get it. Life gets in the way.

If you’ve got kids, or if you work long hours, you’re guaranteed to miss out on sleep every now and then. All things considered, six hours is pretty good under these circumstances. Working out on six hours of sleep, if it’s not too frequent, isn’t going to derail the gains train.

“Working out on six hours of sleep, if not too frequent, isn’t going to derail the gains train.”

When you understand that:

1. Six hours constitutes a lack of sleep, not a sufficient amount, and…
2. Your progress will suffer when you repeatedly don’t get enough sleep,

… what’s left to discuss are the actively negative implications of not getting enough sleep. 👇

The consequences of lack of sleep

Can working out on a lack of sleep be downright detrimental? It’s possible.

Susceptibility to injury

Putting aside the well-documented associations between lack of sleep, or lack of sufficient quality sleep, and all-cause mortality, (7) those who sleep less are more likely to injure themselves during physical activity.

M. D. Milewski et al found that teenagers who chronically undersleep are more likely to sustain sports injuries. (8) If you’re trying to build muscle, this should be concerning. Nothing derails progress like the inability to train due to injury.

Increased hunger and appetite

Lack of sleep also has a very real impact on another of the factors so important to our recovery: nutrition.

Lack of sleep is associated with increased levels of the hormone, ghrelin, with reduced levels of the hormone, leptin. Ghrelin is a hunger signaling hormone, while leptin signals satiety.

In other words, you’ll be hungrier, and food will make you feel less full, simply because you slept less.

Even worse, lack of sleep is associated with impaired impulse control and poorer food choices throughout the day. (9) That means impulsively eating larger quantities of worse foods, while feeling hungrier and taking longer to feel full. Sleeping less is a recipe to get fatter faster.

Catabolic environment

Yep. There’s still more. 🤦‍♂️

Those who lack sleep have higher resting levels of excitatory neurotransmitters and hormones. Cortisol and adrenaline, both released during times of stress, circulate in higher quantities when you lack sleep. Cortisol competes with testosterone (an anabolic hormone essential for optimal muscle growth), and higher levels of cortisol are associated with lower levels of testosterone. (1)

This heightened state of stress downregulates the parasympathetic nervous system, which needs to activate for the body’s processes of rest and repair to kick in.

Together, this can shift the body’s state in favor of muscle protein breakdown, creating a catabolic state in which your body begins to lose muscle. Not to mention kickstarting the vicious cycle of poor sleep —> more stress —> less able to sleep —> more stress still.

Other consequences of lack of sleep:

• Those who commonly sleep fewer than six hours a night have weakened immune systems, and are at much greater risk of certain cancers. (10)
• Lack of sleep also seems to be linked to Alzheimer’s disease. (10)
• Lack of sleep disrupts your blood sugar levels, promotes atherosclerosis (blocked, inflexible arteries), and contributes to mental health disorders. (10)
• When you attempt to diet on too little sleep, most of the weight you’ll lose will come from muscle mass, rather than fat. (10)

“That’s not practical!” | Sleeping in practice

Just in case you’re now worried that a single night of poor sleep will be the last block pulled from the Jenga tower of your physique goals (it won’t), here’s a final reassuring note.

We’re all human, life gets in the way, and what’s ideal almost never lines up with what’s practical. Understanding what’s ideal, though, helps us put our best effort into the right things for better results over time.

So long as you understand you’ll progress fastest while you’re sleeping longest, you’re able to make informed, sensible decisions about how hard you train and how much you sleep.

If you just don’t have time to sleep for eight hours a night, it only makes sense to train with less intensity, volume, or frequency. And, if the circumstances of your life ever change and you’re able to get 10 hours a night no problem, then you know you’ll be able to ramp up your efforts in the gym as a result.

Sleep less and your progress will be slower, but you’ll still make progress, and that’s better than making no progress at all.

References

(1) Bhasin S, Pencina M, Jasuja GK, et al. 2011. “Reference ranges for testosterone in men generated using liquid chromatography tandem mass spectrometry in a community-based sample of healthy nonobese young men in the Framingham Heart Study and applied to three geographically distinct cohorts.” J. Clin. Endocrinol. Metab. 96:2430–39

(2) Brownlee, K. K. et al., “Relationship between circulating cortisol and testosterone: influence of physical exercise.” Journal of sports science & medicine vol. 4,1 76-83. 1 Mar. 2005, PMID: 24431964.

(3) Mah, Cheri D et al. “The effects of sleep extension on the athletic performance of collegiate basketball players.” Sleep vol. 34,7 943-50. 1 Jul. 2011, PMID: 21731144.

(4) Walker, M., Why We Sleep, Kindle Edition, Penguin Books Ltd., 2018, p. 128.

(5) Schoenfeld, B., Science and Development of Muscle Hypertrophy, 2nd edn., Champaign, IL, Human Kinetics, 2021, p. 6.

(6) Walker, M., Why We Sleep, Kindle Edition, Penguin Books Ltd., 2018, p. 129.

(7) Cappuccio, Francesco P et al. “Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies.” Sleep vol. 33,5 (2010): 585-92, PMID: 20469800.

(8) Milewski, M. D. et al., “Chronic lack of sleep is associated with increased sports injuries in adolescent athletes,” Journal of Paediatric Orthopaedics 34, no. 2 (2014): 129-33.

(9) Nedeltcheva, Arlet V et al. “Insufficient sleep undermines dietary efforts to reduce adiposity.” Annals of internal medicine vol. 153,7 (2010): 435-41. doi:10.7326/0003-4819-153-7-201010050-00006, PMID: 20921542.

(10) (6) Walker, M., Why We Sleep, Kindle Edition, Penguin Books Ltd., 2018, pp. 3-4.