You hear how important it is to get a good night’s sleep all the time.  There are many reasons why sleep is important, but what exactly is going on in your body physiologically and how does a lack of sleep affect how fit you are?

 
What Does a Normal Night of Sleep Look Like?

 
According to The National Institutes of Health, we need 8-10 hours of sleep to avoid the dreaded label of being sleep deprived.  I know, I know… sounds crazy right?  I think if more regular gym goers understood that “gains” actually happen while sleeping, more of us would be getting the recommended 8-10 hours each night.
 
Those coveted gains happen at a state of rest because it takes energy to repair your body. While sleeping, you use the least amount of calories to function. Those excess calories can be used most efficiently by your body to help repair itself from going hard at the gym four-to-five times each week.  It doesn’t take a brain surgeon to figure out that by cutting your sleep cycle short, you are sacrificing valuable repair time.
 
And that’s not the only thing your poor sleeping habits are affecting.
 

The Role Your Hormones Play

Let’s dig a little deeper and take a look at exactly how a lack of sleep causes our bodies to adapt to a lack of sleep. Hormone levels can change drastically if you are chronically getting less sleep than you should.  Let’s examine a few that play a role on your waistline. 

Leptin and Ghrelin

Leptin and Ghrelin act on the central nervous system and are big players as far as your metabolism goes. 
 
Leptin helps to inhibit or curb your appetite and signals your body to start burning calories when you need to. If sleep conditions are normal, leptin levels rise and trigger a feeling of being full and have plenty of energy. When you suffer from lack of sleep, leptin levels may drop as much as 19%. This causes you to feel hungry when you are not and tricks your body into thinking it doesn’t have enough energy.
 
Ghrelin triggers the feeling of being hungry when your stomach is empty.  As you eat and get full, the stomach stretches and the production of ghrelin will stop.  Studies have shown that a lack of sleep will cause ghrelin levels to rise.
 
So… what you are saying is that if I’m sleep deprived, I will reduce my body’s appetite suppressant and increasing my body’s appetite stimulant at the same time? YES!  It also may be part of the reason you don’t like the number you see on the scale. 

Learn more about the correlation between sleep loss and Leptin and Ghrelin. 

Human Growth Hormone

Human Growth Hormone (HGH) plays a key part in restoration of the human body.  Yes, HGH is released during your workout, but 75% of the HGH released by your body takes place during stage three sleep, also known as deep sleep. During a proper night’s sleep, you will cycle through deep sleep four-to-five times each night.  If you are not sleeping well, you will not cycle through stage 3 sleep as many times and won’t get your full nightly dose of HGH.  Therefore, your post workout recovery will slow. 

Cortisol

Ahhh… the hormone responsible for “stubborn belly fat.”  Normally, cortisol levels are the highest in the morning and taper off at night.  Think of cortisol as the hormone responsible for giving you the energy to cope with the stresses of life. If cortisol levels are chronically elevated, then you will have a steady stream of energy in your bloodstream, aka glucose. Higher glucose levels lead to elevated blood sugar levels and, eventually, insulin resistance. This is a precursor of diabetes. Studies have shown that cortisol levels drop up to six times slower in sleep-deprived test subjects when compared to control subjects. 

 
The Sleep, Diabetes, and Obesity Correlation

   We all know that diabetes and obesity go hand in hand.  It is no secret that both have been on a meteoritic rise in this country for decades.  According to statistics from the CDC, there were approximately 1.68 million diabetics in the US in 1958, and by 1995 that number had grown to 8.66 million.  Recent CDC stats show that today we have more than 23.35 million diabetics in the US. 
 
It should also be noted that there appears to be data showing a steady decline in the amount of sleep we have been getting over the same time frame.  An American Cancer Society study from 1960 determined we were averaging between 8.0 – 8.9 hours of sleep a night.  Compare that to a 1995 poll that found we were getting around seven hours on average, recent studies have shown we are now sleeping six hours on average per night. 

It’s not hard to connect the dots and see the viable correlation between the growing decline in the amount of sleep we get and the rapid growth in the number of diabetic people in our country.
 
“Multiple studies have shown that short sleep is connected with insulin resistance and metabolic syndrome, which leads to an increased risk of obesity, diabetes and heart disease,” said Lynn Keenan, MD, clinical professor of medicine at UCSF Fresno and program director of the UCSF Fresno Sleep Medicine Fellowship.  “Lack of sleep affects multiple hormones, but an important effect is making the body not use insulin as well.  Insulin is needed to help the body use glucose for energy. With insulin resistance, the glucose rises in the blood and can lead to damage to the eyes, kidneys, nerves and heart over time.

“Sleep deprivation also increases the hormones that make us hungry, especially carbohydrate craving, which can increase the blood sugar,” added Dr. Keenan.

For optimal health she recommends seven to eight hours of sleep.  If you run short on sleep during the work week, she says to be sure to get extra hours over the weekend.
 
I am not sure why the importance of sleep seems, more often than not, to be used as a side note by fitness professionals.  With the evidence presented here, I think you can see that this might just be your weapon of choice to get yourself past that stubborn fitness plateau.
 
Sleep well!
 
By Tim Clark
Manager of Fitness Center