How Not Getting Enough Sleep Affects Your Metabolism

As far as human nature is concerned, sleeping and eating are two of our most basic perfunctory systems. But how do these two connect and affect each other?

In the modern day glorification of “busyness” sleep has taken a backseat, with many adults regularly skimping on their 6-8 hours a night.

The hormonal responses to lack of sleep are fast acting and affect nearly every system of the body. With the US Centres for Disease Control reporting that more than a third of adults get inadequate sleep on a regular basis, we are taking a quick look at the effect of sleep on your metabolism and helpful ways to combat it.

Sleeping and eating are both considered key functions for energy supply and restoration. When the body begins feeling the effect of less sleep, it slows down metabolism in an effort to conserve food energy. This is achieved by hormone changes that slow down other biological functions as well including brain function, digestion, fertility and reproductive cycles, and more.

By moving into this “conservation mode” your body overcompensates for the lack of sleep and causes metabolic disruption. The hormones we are looking at as part of this effect are cortisol, ghrelin, and leptin.


Cortisol is “the stress hormone” and it typically fluctuate throughout the day, with sleep being a vital action for lowering/managing it.

When raised, cortisol will lower the body’s natural functions including:

  • Digestion;
  • Reproduction; and
  • Metabolism.

This lowered metabolism is the body’s response to less energy from lack of sleep in order to conserve food energy.

In addition to lowering metabolism, cortisol increases hunger as the brain is panicking for its next food energy source.

This is where the hormone ghrelin comes into play.


Ghrelin is a hormone released from the stomach that triggers the feeling of hunger (the appetite stimulator).

When the body is fatigued, ghrelin can increase by 20%, according to Michael Breus, PhD sleep specialist (

The cortisol and ghrelin increases are the body’s “panic mode” instinct to trigger your brain to consider its next energy source when proper sleep is not available.

This hormone increases appetite and fat storage and, when coupled with a slowed metabolism and higher cortisol, creates bodily stress and can lead to increased weight with the lack of sleep.


In conjunction with ghrelin increasing, the hormone leptin decreases by about 15% after sleep has been decreased.

Leptin is a hormone that increases energy and inhibits hunger (the appetite suppressor). By decreasing leptin, the body is producing lower levels of energy and more hunger.

This effect on hunger and the appetite is why Brad Russell from Nutritional Cleanse ( says that a healthy, consistent sleep schedule is an essential part of having a healthy metabolism.

A regular sleep cycle will also regulate this hormone production and promote appropriate metabolic function.


Its easy to see the importance of sleep when you consider the hormonal response to lack of sleep and its effect on the entire body, including metabolism and eating habits. The best way to combat these imbalances is to ensure you sleep well and often enough. Decreased caffeine later in the day, reducing light exposure in the evenings, nutritional diet and exercise are also easy, great steps to keep you well rested and establish a “healthy metabolism”.


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