Can I Build Muscle While I Sleep?

Shannon Miller

July 25, 2019

Is it possible to build muscle without any effort (or…consciousness)? Heather Huntsman, Ph.D., CSCS, weighs in on two basic principles of muscle building rooted in research that could help you maximize lean muscle mass growth without lifting a barbell.

As a scientist and a lifelong athlete who has tried just about everything to perform at the highest level, I’m trained to be a skeptic of certain “quick fix” claims. And rightfully so. Most shortcuts are misinformation that ultimately lead to disappointing results. When it comes to fitness and maintaining a healthy weight (i.e. low body fat and a high percentage of lean body mass) it always comes back to the basics. You cannot trick physiology. Eating a well-balanced diet, being mindful of the total calories consumed, and maintaining an active lifestyle is the only way to do it. Although there are exercises and foods that are better than others, it depends on the individual and their goals.

One “shortcut” question I’ve come across: Can you build muscle while you sleep? If the answer is yes, where do I sign up?!

The true answer relies on two basic principles important to muscle building.

Muscle Adaptation

First, in order to build muscle, you must load the muscle in such a way that drives adaptation. Fortunately, the strategy to maximize muscle adaptation is well researched and clear. Lifting weights to failure (i.e. doing enough repetitions in one set to completely fatigue the muscle group) is the best way to build muscle in a single workout. Then, build in a progressive overload (i.e. increase weights slowly from workout-to-workout as the exercises becomes easier). This is the main “protocol” for resistance training over time to prevent injury and drive adaptation.

Muscle Repair

The second principle important in the muscle building process is to ensure the body has enough fuel to allow for muscle repair and adaptation to an exercise stimulus. These building blocks are called amino acids and are the most basic components of protein. Muscle growth requires a sufficient amount of amino acids for the building process.

So, if I eat enough protein at the right time, I’m good? Now we are onto something!

Because of the time it takes to digest protein, a steady stream of amino acids is typically only available in our system for approximately 5 hours. This begs the question: what happens during the sleeping hours? If you’re lucky, you get the recommended 7-9 hours of sleep at night. Doing the math, even if we eat adequate amounts of protein for dinner, there is about a two- to four-hour window of opportunity where our muscles are repair from physical training, but the amino acids necessary for this repair are limited or non-existent.1

This means by taking the window of opportunity to allow amino acids to stay in your system longer, you may maintain the muscle building process and enhance recovery, lean muscle gain, and even performance. What does the research say? More slowly digested and absorbed protein like casein (~30-40g) consumed prior to sleep can enhance muscle building and improvements in strength.2 Because casein takes more than 7.5 hours to fully digest and absorb, it covers this window of opportunity more fully and effectively.1 Unfortunately, it has no effect on fat burning or resting metabolic rate3 and still needs to be combined with resistance training to be effective.4,5 Remember, it’s an opportunity not magic! So, despite my initial instincts to dismiss this concept as one of the many misinforming, hyped-up fitness tricks aimed at beating the system, this one is actually supported by science.


  1. Trommelen J, and van Loon LJC. (2016) Pre-sleep protein ingestion to improve the skeletal muscle adaptive response to exercise training. Nutrients 8,763.
  2. Kerksick CM, Arent S, Schoenfeld BJ et al. (2017) International Society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition 14(33).
  3. Snijders T, Trommelen J, Kouw IWK, et al. (2019) The impact of pre-sleep protein ingestion on the skeletal muscle adaptive response to exercise in human: an update. Frontiers in Nutrition 6(17):1-8.
  4. Snijders T, Res PT, Smeets JSJ, van Vliet S et al. (2015) Protein ingestion before sleep increases muscle mass and strength gains during prolonged resistance-type exercise training in healthy young men. The Journal of Nutrition 145:1178-1184.
  5. Antonio J, Ellerbroek A, Peacock C, et al. (2017) Casein protein supplementation in trained men and women: morning versus evening. International Journal of Exercise Science 10(3):479-486.


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