Sleep Your Way to Fat Loss & More Muscle

If you read my last post, you know that achieving a healthy body composition isn’t really a singular goal, it’s two: decreasing excess body fat and increasing lean muscle mass. Regardless of which goal you may be interested in working on, getting the right amount of sleep isn’t recommended; it’s required.  Here’s why.

Sleep is a multi-faceted process that’s more complex than many of us realize. In fact, it’s so nuanced and complicated that an entire field of scientific study has been dedicated to it. Researchers divide sleep into two categories: REM sleep (when dreams occur) and NREM or non-REM or dreamless sleep.

NREM sleep is divided into the following stages:

Stage 1 which accounts for only 5-10% of your sleep and is referred to as light sleep. In this stage, you remain semi-conscious and are in between wakefulness and sleep. Your brain waves begin to elongate and slow from alpha to theta waves.


Stage 2 accounts up to 55% of your sleep cycle. In this stage you are fully asleep, and your brain waves slow down even more.


Stage 3 is the deepest of all the sleep states. It’s characterized by very elongated brain waves and slow brain activity.  Slow wave sleep accounts for just 15-25% of your sleep but is arguably the most important sleep state for your body composition because most of the restorative benefits of sleep occur during this cycle.

REM is a distinctly different type of sleep that is characterized by increased brain activity in conjunction with what is essentially complete physical paralysis.


You pass through these four sleep stages every 90 minutes in a 1- 2 - 3 - 2 - REM sequence. If you’re getting 7-8 hours of sleep each night, you should be experiencing 4-5 cycles.

Sleep & Growth Hormone (GH)

Going through a complete sleep cycle ensures that you will pass through stage 3 sleep when growth hormone (GH), one of the body’s most important anabolic (productive) hormones, is released. As its name implies, growth hormone directly contributes to the development of muscular size and strength. The total amount of GH released in your body is directly correlated with how much Stage 3 sleep you get.

Sleep & Testosterone

A second important anabolic hormone, testosterone, is also significantly affected by sleep and sleep loss. Testosterone plays a key role in muscle growth. Although men naturally produce more testosterone than women, both sexes increase their testosterone production when they exercise. This testosterone boost has the potential to promote muscular development. As with growth hormone, testosterone secretion has been linked to stage 3 sleep. Several studies have confirmed that sleeping 5 hours or less will reduce testosterone production in otherwise healthy men and women.

Sleep & Cortisol

Sleep—or the lack of it—also has a significant impact on a second group of hormones, the catabolic (destructive) hormones, specifically a hormone called cortisol. Cortisol is a hormone that is released in response to stress. It’s designed to break down tissues–including muscle—in order to provide the body with the immediate energy it needs to manage whatever stressful situation is at hand.

Research has shown that during both restricted sleep and complete sleep deprivation, cortisol levels were elevated the following evening by 37-45% significantly accelerating the onset of negative metabolic and cognitive consequences that include:

  • Hunger hormone dysregulation. Irregular sleep throws off your ghrelin and leptin cycles, making you feel hungrier.


  • According to scientists, sleeping less encourages more snacking between meals, which can create an energy imbalance and increased fat stores.


  • Sleeping less can cause reductions in your Basal Metabolic Rate (BMR) by as much as 20% significantly reducing your total energy output.


  • Being tired also reduces the body’s proclivity for spontaneous movements, further reducing your total energy output.

When your cortisol levels remain high, your primitive brain convinces your body that it’s facing an impending danger or scarcity. As protective defense, it will begin to store more fat around the midsection to prepare itself for survival. Every time the body is forced to mobilize its resources to protect itself from a stressful or threatening event (real or imagined), levels of insulin—the body’s fat storage hormone—rise. Increased cortisol levels naturally elevate blood sugar, which theoretically serves as an extra, back-up energy source the body can use to defend itself. While our physiology was programmed to work for us during primitive times, it can often work against us in the modern world.

Still not convinced that getting enough sleep should be a top priority for peak health and performance?

Consider the following health benefits of sleep:

  • Sleep reduces chronic inflammation, which not only interferes with the body’s ability to build and maintain muscle, but makes us more susceptible to recurring injuries and chronic disease.

  • Dozens of studies confirm that good quality sleep can improve our motivation and willpower, which naturally translates into improved training and racing performance. 

Need some tips and tactics that can help you get and benefit from more consistently restful sleep? Stay tuned for my next post. We’ll investigate and navigate the topic of good sleep hygiene and what it can do to increase your personal health and performance.

About the author

Jackie Cruickshank Cohen is an NBHWC Board Certified Health and WellnessCoach, True Cellular Detox Certified Practitioner, author, and elite master’s athlete.