What Happens to Your Body When You Sleep?

For most people, a good night’s sleep is about more than feeling refreshed the next morning. It’s a vital health and wellness process that affects nearly every tissue and system in your body. It impacts your mood, metabolism and immune function. It also impacts your risk for heart disease, diabetes, depression and obesity. Even missing out on a few hours of sleep can significantly increase your chances for developing these disorders, which often stem from lifestyle factors such as poor diet and lack of exercise.

When you get a decent night of sleep, your muscles are healing themselves, your blood pressure is lower, and your brain is cleaning out the waste it accumulates throughout the day. All of these activities are essential for physical and emotional well-being.

While some of the benefits of sleep are fairly obvious, understanding what happens to your body as you slumber is more complex. For decades, researchers have been trying to understand why we sleep and what the role it plays in our bodies and health.

One of the most important discoveries was made by UChicago professor Nathaniel Kleitman, who established the world’s first lab devoted solely to studying sleep and its patterns. His work led to the development of electroencephalogram (EEG) technology, which allowed scientists to observe and record brain activity during sleep. In 1983, he discovered that rats who were continuously deprived of sleep died within two weeks, proving the importance of this vital life-support activity.

Another theory of why we slumber is the energy conservation hypothesis, which says that sleeping through the night allows animals to conserve energy they would otherwise use in the daytime for searching for food or avoiding predators. The third non-rapid eye movement (NREM) stage of sleep appears to be particularly important for this purpose. In addition, the glymphatic system, which clears out waste from the brain, is most active during this phase.

During the NREM stage of sleep, your brain is preparing memories to be converted from short-term to long-term storage and may be erasing unnecessary information. This helps explain why people who don’t get enough sleep can have trouble remembering things, especially in stressful or difficult situations.

Cognitive Performance: Getting a good night’s sleep can help you concentrate better at work or school, make smarter decisions and be more creative. In fact, some studies suggest that people who get adequate amounts of sleep have a lower risk for dementia and Alzheimer’s disease than those who don’t.

Mood: People who don’t get enough sleep have a harder time controlling their emotions and making healthy decisions, and they are at higher risk for anxiety and depression. Mood disorders can also contribute to insomnia and restless sleep.

If you want to learn more about how you can improve your sleep, there are many resources available online. The National Sleep Foundation offers a bedtime calculator and sleep diaries, as well as tips on how to manage your sleep. It also features an extensive library of articles and videos, including interviews with top sleep experts.