Sleep is essential to the functioning of every system in your body. Yet scientists are only beginning to understand why humans and other animals need sleep. Some theories suggest that sleep evolved as a way to reduce the risk of predator attacks during the night, while others say that sleeping simply helps us recover from the stress and exhaustion of our day-to-day lives.
What we do know is that sleep appears to play a critical role in regulating our appetites, our moods, and our emotional responses. It also helps maintain our physical health and immune systems.
During sleep, the brain releases chemicals that help repair and protect the tissues in our bodies. These chemicals are important for maintaining a healthy weight, as well as preventing and treating certain diseases, including heart disease, stroke, and diabetes.
While some people need more sleep than others, everyone needs a good amount of rest. Infants, teenagers, and adults need seven to eight hours of sleep per night on average. If you get too little sleep, you will feel tired and irritable the next day, and it can affect your memory and concentration. Lack of sleep may even contribute to certain mental illnesses, such as depression and anxiety.
When we go to bed, the first thing that happens is that a part of the brain called the hypothalamus triggers a series of changes in the body and brain. These changes reduce your alertness, and electrical signaling in the brain begins to slow down. Eventually, brain activity shifts into different wave patterns — from rapid alpha waves to slower theta and then deep slow-wave patterns — a pattern that is characteristic of sleep.
As the brain continues to shift through these phases, it becomes more active in areas of the brain that regulate emotion and control behavior. It is during this stage that we dream and process memories. Getting a poor night’s sleep can affect our ability to concentrate and learn, which can affect our job performance, school grades, and personal relationships.
It’s a good idea to keep a regular sleep schedule, going to bed and waking up at the same time each day. You can also try to relax before you go to bed, and make sure the environment in your bedroom is comfortable and free of distractions.
In 1953, a pair of sleep scientists at the University of Chicago made one of the most significant discoveries in the history of sleep research. Nathaniel Kleitman and Eugene Aserinsky discovered a phase of sleep known as REM (rapid eye movement) sleep, during which the brain’s patterns most resemble those when you are awake. The discovery of REM sleep is one of the key milestones in understanding the nature and importance of human sleep. It is also the stage of sleep during which dreams occur. In addition, REM sleep is important for learning and memory. In fact, a recent study found that people who have a family history of heart disease or stroke are more likely to experience those conditions if they get too little REM sleep.