This New Year’s, you made a promise to yourself yet again: this is the year you are going to start working out consistently to lose weight and gain muscle. You find a gym, sign up, and start going. You’re excited and feeling good about yourself.

A month passes. And another month. And another. And, somehow, half a year later, you find that not much has changed physically. You know that it takes time, but you’re confused because you’ve been fairly consistent in going to the gym. Maybe you’ve even tweaked your nutrition so you’re eating more vegetables and whole foods. Why isn’t it working? What haven’t you thought of?

The answer might just be: sleep.

Before we delve into the physical benefits of sleep, let’s review the basics of muscle growth. The scientific term for muscle growth, or an increase in the size of muscles, is muscle hypertrophy, or an increase in the size of muscles. The types of muscle we’re talking about are our skeletal muscles, the muscles attached to our bones – think quadriceps, calves, biceps, triceps, lats. When you exercise – especially in the form of weightlifting or resistance training – you put a strain on your muscle fibers. This creates micro tears, otherwise known as muscle damage. This damage activates a specific type of cell, called satellite cells, which can eventually become skeletal muscle cells. Activation of the satellite cells causes them to fuse with each other and to muscle fibers. The fusion to muscle fibers forms new muscle protein strands, increasing the total number and thickness of muscle protein strands. This is what we call hypertrophy, or muscle gain. It’s important to note that hypertrophy is a relatively slow process that can be affected by many factors, including age, sex, body size, body composition, and hormone levels. 

There are many ways to support muscle growth. Probably one of the most well-known methods is to eat an adequate amount of protein as a part of a well-balanced diet. Not only do protein-rich foods reduce hunger due to their high satiety, but protein is the actual component used by the body to build up and repair muscle tissue. Protein intake is especially important for preventing muscle loss during a fat loss phase.

Rest, however, is a highly underestimated method for supporting muscle growth. Inadequate sleep has been shown to affect fat metabolism, causing fat to be preferentially stored rather than processed, leading to a predisposition for weight gain. Other studies have shown that attempts to lose fat, despite dietary intervention, can be curtailed by a lack of sufficient sleep. Poor sleep is also associated with increased levels of the ‘hunger hormone’ ghrelin and decreased levels of the ‘appetite suppressor hormone’ leptin, as well as reports of feeling hungry. Furthermore, sleep deprivation also negatively impacts workout performance – energy expenditure and aerobic power are lowered by poor sleep and time to exhaustion is severely diminished as well. Interestingly, the relationship works both ways – better sleep (e.g. falling asleep quickly, sleeping with minimal awakening, and spending more time in REM and deep sleep) leads to better athletic performance, and exercising can lead to better and longer sleep.

So, more or better sleep won’t build your muscles any faster or bigger, but sleep deprivation can hinder your efforts to lose fat, gain muscle, and perform well athletically. If you’re working hard in the gym and eating well, the next factor to optimize is sleep. A good night’s rest will not only support your efforts to achieve that New Year’s Resolution, but will put a smile on your face as well.

Peer edited by Colleen Lawrimore

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