It turns out that spending more time working out will not necessarily give you better muscle tone. It may not seem obvious, but getting a good night’s sleep is critical to your ability to improve your lean muscle mass and show off the benefits of your hard work in the gym.

Will You Shed Fat or Muscle Mass While You Sleep?

A key early study on sleep and muscle mass looked closely at the weight lost by dieters who slept enough (8.5 hours) or an inadequate amount (5.5 hours).

This research, which was published in the Annals of Internal Medicine, found that both sets of people lost the same amount of weight. However, the researchers found that the people getting 8.5 hours of sleep lost more than 50% of their weight as fat.

In contrast, the dieters who got 5.5 hours of sleep lost only 25% of their weight as fat.  The rest was lost muscle mass.

This effect is not just for dieters. If you exercise vigorously but don’t get enough sleep, your muscle mass can actually decrease.

Why Does Sleep Affect the Growth of Your Muscles?

When you work out during the day, your muscles break down. However, they rebuild after you go to sleep and relax – increasing the blood flow to the muscles.

For you to gain muscle mass, you need to build more muscle than you broke down during the day.

If you don’t sleep enough, your body will break down more muscles than it builds. The reason for this is that hormones that are produced when you sleep deeply accelerate the process of building muscles.

When you don’t get enough sleep, your body secretes hormones that cause the muscles to break down. Instead of using your fat as fuel, your body uses your muscles.

This phenomenon was studied in more than 10,000 Chinese college students. The researchers looked at the strength of the students’ handgrip and used that as a measure of their muscle mass. They found a strong association between the quality of sleep and great muscle strength in both men and women.

Less Sleep Makes You More Fat

As if losing muscle mass while you sleep weren’t bad enough, the shortage of sleep also stimulates fat gain. There are several reasons for this.

One is that if you don’t get enough sleep, your appetite goes out of control, and you are more likely to overeat. This happens because sleep affects the regulation of the hormones that regulate your appetite (leptin and ghrelin).

However, even if you eat properly, you may still gain fat while you sleep if you are sleep deprived. If you don't get enough sleep, your body secretes the stress hormone cortisol, which tells your body that it’s under attack.

Your body goes into fight or flight mode, acts like it’s starving, and causes the storage of extra fat – especially in the abdomen.

How to Make Sleep Work for You

You may need to change your emphasis from fitting in workouts around a limited sleep schedule and instead prioritize getting enough sleep.

Your trainer can help you devise a strategy, so you get the best out of your workouts while leaving enough time for adequate sleep – and showing off your greatly improved muscles! Stop by the front desk and ask about our Personal Training program today to get started!