What Happens When We Sleep?

Getting enough sleep is important for your health, but it can be hard to do. Our hectic, fast-paced lives can make sleeping regularly seem like a luxury, even though it’s as essential to your wellbeing as eating and exercise. A good night’s sleep improves your mood, brain function, and immune system. It also helps you recover from illness and stay alert. Getting plenty of quality sleep is especially important for athletes, as it helps them perform at their best and avoid injuries.

However, scientists are still a long way from fully understanding what happens when we sleep. Modern medicine’s understanding of sleep is like a partially assembled jigsaw puzzle: experts know what the pieces look like, but haven’t yet figured out how they fit together. It is well known that sleep affects our memory, and that poor sleep leads to forgetfulness, such as when we can’t recall someone’s name or how we left the stove on or forgot to charge our phone. Despite years of study, researchers haven’t been able to explain why. One theory is that during sleep, memories are committed to long-term storage while other information is discarded (Szymusiak and Deboer, 2010). Another theory involves a process called “sleep spindles,” in which brain waves generate brief sequences of activity that resemble the synapse-firing patterns that occur during wakefulness. The theory is that these sequences of activity allow the neocortex to respond, overtly or covertly, to external stimuli during sleep without waking up (Andrillon and Kouider, 2020).

Research also shows that people who get more quality sleep have better immune systems. That’s why it’s so important to stick with a regular bedtime and keep electronic devices out of the bedroom, as they can interfere with the body’s natural rhythms. Scientists are noticing more links between inflammation and sleep as well: A September 2021 study in Frontiers in Neurology found that C-reactive protein, an indicator of inflammation, increases when people don’t get enough sleep.

A good night’s sleep also helps us learn, remember, and create. A study published in December 2021 in Science Advances found that people who were well rested when they performed a cognitive task had more creative solutions than those who were not. It’s likely that this is because during sleep, the neocortex reorganizes and consolidates memories in ways that we are not aware of.

Getting enough sleep is also important for healthy growth, as it triggers the release of hormones that help children and adults grow, and maintain muscle mass. It is also important for mental health, as it allows for more stable emotions and helps to reduce the risk of mental disorders like depression and anxiety.

During sleep, the brain also gets rid of waste, such as the proteins that build up in Alzheimer’s patients. In addition, a recent study found that in mice, when the neocortex was exposed to stimuli while asleep, the right hemisphere of the brain responded while the left did not—reinforcing the idea that sleep is a state of lowered responsiveness.