Turns out, sleep deprivation is a little like being drunk. You just don’t have the mental clarity to make good complex decisions, specifically with regards to the foods you eat—or foods you want to avoid. This isn’t helped by the fact that when you’re overtired, you also have increased activity in the amygdala, the reward region of your brain. This is why sleep deprivation destroys all diets; think of the amygdala as mind control—it makes you crave high-calorie foods. Normally you might be able to fight off this desire, but because your insular cortex (another portion of your brain) is weakened due to sleep deprivation, you have trouble fighting the urge and are more likely to indulge in all the wrong foods.
And if all that wasn’t enough, research published in Psychoneuroendocrinology found that sleep deprivation makes you select greater portion sizes of all foods, further increasing the likelihood of weight gain.
The bottom line: Not enough sleep means you’re always hungry, reaching for bigger portions, and desiring every type of food that is bad for you—and you don’t have the proper brain functioning to tell yourself, “No!”
Sleep Sabotages Gym Time
Unfortunately the disastrous impact spreads beyond diet and into your workouts. No matter what your fitness goals are, having some muscle on your body is important. Muscle is the enemy of fat—it helps you burn fat and stay young. But sleep (or lack thereof) is the enemy of muscle. Scientists from Brazil found that sleep debt decreases protein synthesis (your body’s ability to make muscle), causes muscle loss, and can lead to a higher incidence of injuries.
Just as important, lack of sleep makes it harder for your body to recover from exercise by slowing down the production of growth hormone—your natural source of anti-aging and fat burning that also facilitates recovery. This happens in two different ways:
1. Poor sleep means less slow wave sleep, which is when the most growth hormone is released.
2. As previously mentioned, a poor night of rest increases the stress hormone cortisol, which slows down the production of growth hormone. That means that the already reduced production of growth hormone due to lack of slow wave sleep is further reduced by more cortisol in your system. It’s a vicious cycle.
If you're someone who doesn't particularly enjoy exercise, not prioritizing sleep is like getting a physical examine with your father-in-law as the investigating physician: It will make something you don’t particularly enjoy almost unbearable. When you’re suffering from slept debt, everything you do feels more challenging, specifically your workouts.
The Better Health Secret: Prioritize Sleep
The connection between sleep and weight gain is hard to ignore. Research published in the American Journal of Epidemiology found that women who are sleep deprived are a third more likely to gain 33 pounds over the next 16 years than those who receive just seven hours of sleep per night. And with all of the connections to obesity, diabetes, high blood pressure, heart failure, and cognitive failure, the need to sleep goes far beyond just looking better and seeing results from your diet and exercise efforts.
While there’s no hard number that applies to all people, a good rule of thumb is to receive between seven and nine hours of sleep per night, and to make sure that one poor night of sleep isn’t followed up with a few more. It might not seem like much, but it could make all the difference and mean more than any other health decision you make.