We all know the feeling after a bad night’s sleep.
You wake up groggy and grumpy, you drag your feet out the door, you sip second and third cups of coffee, but the exhaustion is still there. You spend your day in a fog.
And the nag of sleepiness isn’t the only downside of poor rest: your body composition goals might be in jeopardy, too. Your body needs sleep to function at its best, and it’s willing to punish you for stealing that away. As we’ll see, missing beauty sleep doesn’t just sap energy and motivation. It brings the gears of fat loss and muscle growth to a grinding halt—and may even reverse your progress. Whatever your goals are, bad sleep is a wrench in your machine. Let’s look at what goes on under the hood when we stop sleeping well, and what we can do to get our engine humming again.
Sleep and Fat Loss
You may have noticed that not sleeping well has some interesting effects on your appetite. Many people report that they feel hungrier after a bad night of sleep, and several studies have shown that sleep-deprived people are hungrier than their well-rested peers. Not only do subjects report higher levels of hunger, but blood samples looking at key hunger hormones tell the same story [10]. Subjects who were sleep deprived had increased ghrelin (a hunger hormone) and decreased leptin (a satiety hormone), and their hunger scores were directly related to these hormone changes.
If you’re trying to lose a few pounds, this certainly doesn’t help. Obviously, the added hunger after missing sleep can lead to overeating. What’s worse is that people often report a craving for high-sugar and high-fat foods (such as pastries and desserts) during times of sleep insufficiency [3]. On their own, these foods aren’t inherently bad. However, they’re easy to overeat, which can result in a calorie surplus and weight gain in the long run.
And other studies have found that lower amounts of sleep are associated with higher BMI and higher risk for obesity and diabetes [1, 7]. Poor sleep and fat loss don’t mix very well. So, if your goal is to maximize fat loss, your success may depend on getting a good night’s sleep.
Sleep and Muscle Gain
When we think about building muscle, we picture sweating it out in the gym. Of course, training hard is important for building mass, but all the hard training in the world can be thwarted by poor life choices. This is especially true when it comes to sleep.
Studies have shown that insufficient sleep can decrease your strength [8]. Progressive overload is one of the keys to building muscle mass, and lifting lighter weights with sleepy arms isn’t going to get the job done. So, if you want to hit the heavy weights and build muscle, you have to prioritize good, consistent sleep.
But lower strength isn’t the only consequence of poor sleep. Research also shows that muscle glycogen stores (the carbs your body keeps in muscle tissue for energy) are depleted after insufficient sleep [9]. Without these energy stores, it will be very hard to put in the right effort on high-rep sets. Weakness and lack of energy isn’t a good recipe for crushing gym sessions and building muscle.
Not only does sleep directly affect your workout, it also impacts your recovery afterward. We tend to focus on tearing down our muscle fibers and overlook the importance of building them up again. Most of these repairs happen while we sleep! Theoretically, losing out on sleep reduces the amount of time your body spends in ”repair mode,” resulting in less overall growth. Plus, losing sleep leads to increased catabolism (tissue breakdown) and decreased anabolism (tissue building) in the body [2]. That means sleep deprivation actually promotes the destruction of muscle tissue and inhibits the things that build it. In the long run, this might lead to a net loss of muscle. Not good.
The Habits and Hygiene of Sleep
Now, you’re probably wondering how much sleep you need and what counts as “good sleep.”
Most research on sleep and performance has set the minimum at seven hours [4], but this is highly variable. For example, it’s common for elite athletes to need as many as ten hours of sleep for full recovery. The rest of us might be able to get away with less, but trial and error is the only way to find the magic number. Once you nail down the right amount, make sure that you schedule your day around sleep rather than taking what you can get after the day is done. Make it a priority: Getting the right amount of sleep allows us to maximize the quality of the time we spend awake.
And sleep quantity isn’t the only thing we need to worry about. Quality is just as important. Ten hours of tossing and turning just isn’t going to do the trick. We want to make sure that we sleep soundly throughout the night to take advantage of the hours we’re putting in. So, to get that awesome night of sleep on a regular basis, you need to get a handle on your “sleep hygiene”:
Put It to Rest
Most of you know that sleep is important for general health, but the impact it has on your body composition isn’t as obvious. The evidence is clear that getting enough sleep is imperative for success in the gym and on the scale. Giving sleep the respect it deserves can be a difficult trick to master, but the strategies above can make it easy. Eventually, resting like a king or queen will feel like second-nature.
Getting a handle on these sleep basics will go a long way toward helping you lose fat and gain muscle. And as a bonus, you’ll feel better, more focused, and more productive in your daily life. If you want to boost your performance in the gym and progress in the mirror, take the time to prioritize your sleep. The benefits are hard to beat!