How Lacking Sleep Impacts Your Fitness

The negative side effects of not getting enough sleep

Here’s the problem: Americans have a major issue when it comes to sleep deprivation. More than 30 percent of us are sleep-deprived. Meaning that we’re not getting the recommended 7-8 hours of sleep a night required for adults, according to the Centers for Disease Control and Prevention. Which in turn means that approximately 108 million people in the U.S. are sabotaging their own fitness goals. Without the proper amount of sleep, all sorts of negative side effects can arise, from day-to-day sluggishness to heart disease, diabetes, and other serious conditions.

When it comes to exercising, sleep can play a huge role in how your body functions, grows and changes. Having a good night’s sleep is a crucial part of your health routine. So if you don’t have healthy sleep habits already, this is why you should really consider spending quality time with the Sandman.

Why Sleep Deprivation Is Detrimental To Your Health

Sleep is very important, yes. You probably knew this already just by being a human. But now, there is even more bad news out there for those who skip out on their zzz’s. Sleep deprivation may also help contribute to unwanted weight gain and muscle loss.

That’s the conclusion of a recent study conducted at Uppsala University in Sweden, the results of which were published in the journal Science Advances. Fifteen participants took part in two tests. In the first, they got a normal amount of sleep defined as “over eight hours,” which is both correct and, in real-world terms, sadly aspirational for many of us. During the second session, they were kept awake for the entire night via a variety of methods that included, keeping the lights on, watching movies, and alternating between card games and board games. 

After only one night of sleeplessness, they observed tissue changes that were indicative of increases in both adiposities. Which is the ability of adipose tissue to store fat, and levels of the hormone cortisol, which promotes the breakdown of muscle tissue. In other words, sleep deprivation looks like a very efficient way to deprive yourself of the results you may be striving for in the gym too. 

2008 study published by the New York Academy of Sciences determined that lack of sleep is “associated with a dysregulation of the neuroendocrine control of appetite.” This is the fancy way of stating the lesson that everyone who has gone out for too many nights in a row learned the hard way: If you’re tired all the time, your body will start thinking it’s hungry even when it’s not, and you’ll crave more food.

How Sleep Works To Recover Your Body 

Of course, we know that sleep is important for our health. Our alertness and mood are the primary things that come to mind if we’re lacking in sleep. But did you know that sleep is important for regulating the central nervous system as well as your brain function?

Sleep also affects the immune system. For example, people who sleep less than five hours are five times more likely to have a cold. This in comparison to people who sleep for seven hours a night. So, the more you sleep, the better your health.

Overall, sleep gives your body time to recover, conserve energy, and repair and build up the muscles worked during exercise. When we get enough good quality sleep, the body produces growth hormone. During childhood and adolescence, growth hormone makes us grow. As you can guess from the name, when we are older growth hormones helps us build lean muscle and helps our body repair when we have torn ourselves up during a hard workout. Essentially, producing growth hormones are a cornerstone of athletic recovery. 

How Workouts Can Ward Off Sleep Deprivation 

In one study published in the journal Sleep Medicine, individuals with a self-reported sleep time of fewer than 6.5 hours completed moderate-intensity workouts (think walking, riding a stationary bicycle, or running or walking on a treadmill) four times a week for six weeks. At the end of the experiment, they reported getting an extra 75 minutes of sleep per night.

Working out also helps you maintain your circadian rhythm (your body’s internal clock). Essentially,  exercise helps your body understand the schedule it’s on. Morning exercise especially primes your body to sleep better at night.

That said, you’re probably better off sticking to low-intensity workouts. Think yoga, pilates, or barre, if you plan to sweat close to bedtime. Research published in the September 2014 issue of the European Journal of Applied Physiology found that high-intensity exercise has been shown to delay sleep onset, probably because of an increased heart rate post-gym time. Everyone is different when it comes to how stimulating any one particular workout might be. If you have trouble falling asleep, getting your heart rate up too close to bedtime may be contributing to that. Though for others, breaking a sweat at the end of the day may not affect sleep.

Why Sleep Is Essential For Your Fitness Regime

The better rested you are, the better your mind and body function. This includes at the gym. Adequate sleep has been proved to help motivate people to stick to their exercise plans and work out the next day. According to research published in the Journal of Clinical Sleep Medicine, the more sleep time individuals in this study got, the more likely they were to complete their exercise regimen.

That’s not to say that suddenly getting 8 hours of sleep a night will turn you into a sports superstar. Extra sleep won’t necessarily make you faster, stronger, or improve your times or performance. Rather, sleep deprivation has been linked to physiological responses. Such as autonomic nervous system imbalances. Which are similar to overtraining symptoms like sore muscles and a higher risk of injuries. All of these can inhibit your athletic performance.

With that said the connection between sleep and weight gain is hard to ignore. Research has found that women who are sleep deprived are a third more likely to gain 33 pounds over the next 16 years. This is in comparison to those who receive seven hours of sleep per night. 

There’s no hard number that applies to all people. However, a good rule of thumb is to get between 7-9 hours of sleep per night. Also, it’s key to make sure that one poor night of sleep isn’t followed up with a few more. Which might not seem like much. However, it could make all the difference and mean more than any other health decision you make.

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Lesley George

Lesley is a content writer and community manager at Shape.

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