The POWER of Sleep!

March 24, 2023 2 min read

As a physician and performance specialist, I routinely observe patients seeking to improve their strength and physical performance, often focusing on strict workouts, dietary adjustments, and supplementation. All of which are important components to strength and performance, obviously.

However, one crucial factor tends to be overlooked:  sleep.

In recent years, research has again and again demonstrated the profound impact that sleep has on physical health and athletic performance so let’s look at the science behind sleep’s role in optimizing both.

Let’s start with the basics of sleep to better understand how sleep influences strength and performance. Sleep is typically divided into two categories: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM consists of 3 stages while REM is a singular stage and each has a specific function. 

In regards to physical performance and strength we will touch on the 2 most influential:

NREM Stage 3: known commonly as deep sleep or slow-wave sleep, this is the most restorative stage where the body focuses on repairing tissues, building bone and muscle, and strengthening the immune system.


REM Sleep: the stage during which dreaming occurs and is vital for cognitive function, like memory consolidation and problem solving.

So how are these two stages of sleep connected to strength and performance?

Well, adequate sleep, particularly those 2 stages, is critical for physical recovery, strength development, and performance enhancement!

In addition, sleep contributes to enhancing those aspects in several ways such as:

  • Muscle Growth and Repair

During NREM Stage 3, the body releases growth hormone which stimulates muscle growth and repair. Poor sleep can hinder this process and lead to slower and lesser recovery and strength increases.

  • Energy Restoration:

Sleep is essential for replenishing energy like glycogen and ATP stores which fuel intense activities required through the day and insufficient rest can reduce levels and thereby lower energy and strength output.

  • Injury Prevention:

Sleep deprivation greatly increases risk of injury due to impaired motor skills, reaction time, and reduced focus. Getting enough sleep allows for proper physical recovery as well as cognitive recovery thus reducing injury likelihood.

  • Hormonal Balance:

As mentioned earlier, sleep time is when growth hormone is released, but it also regulates other hormones like testosterone and cortisol which play important roles in strength increases and muscle gains, fat loss, and overall physical performance. A lack of sleep can be detrimental to this hormonal balance and significantly decrease strength and performance.

  • Motor Skill Learning:

Now back to REM. Remember the memory consolidation aspect of this stage? Well that includes procedural memory like motor skills! And athletes who get sufficient sleep demonstrate far greater motor skill learning and faster adaptation to new movement patterns!

That’s a lot of influence, right?!

Needless to say, sleep is one of, if not the most, impactful ingredients to improving strength and physical performance in an individual. Whether a high level athlete or a banker in a cubicle, sleep is imperative to gaining and maintaining strength and performance.

Don’t let a lack of sleep lead to subpar performance and strength.


Kirk Parsley, M.D.