Sleep is one of the most important things that people can do for their physical and mental health. Getting enough good quality sleep can help prevent diseases and disorders, such as heart disease and high blood pressure. It can also help improve memory, make it easier to learn new information and maintain a healthy weight. However, the amount of sleep that is needed varies from person to person and can even change as you age.

Fortunately, the body has built-in sleep cycles that work on a daily schedule. These rhythms are called circadian rhythms and they affect how the body and brain feel at various times of the day. People who have regular sleep patterns, for example going to bed and waking up at the same time every day, tend to get better quality sleep.

It’s also possible to increase the quality of sleep by maintaining a relaxing routine before bed, eating well and keeping a cool temperature in the bedroom. If you still can’t seem to get the restful sleep that you need, it may be worth speaking with a health care provider.

Researchers are only beginning to understand the many functions of sleep. One theory is that sleeping enables the brain to recharge after a day of activity. Another is that it helps the body repair itself, particularly the cells and tissues. Finally, some research suggests that sleep is critical for memory. In fact, studies show that it is harder to remember something that you learned just a few hours before if you did not get enough sleep.

When you are asleep, your body and brain go through four stages of sleep each night. The first two are non-rapid eye movement (NREM) sleep and the last stage is rapid eye movement (REM) sleep. During these phases the brain and body go through changes that affect almost all of the cells in the body.

As you sleep, your immune system goes to work. It is this system that protects you against infections and illness like the common cold. It is also the system that fights cancer and other deadly conditions. Studies have found that when you don’t get enough sleep, your immune system’s ability to fight off germs and harmful substances is decreased.

In addition to affecting your immune system, the quality of your sleep has a direct impact on your memory. During sleep, your brain makes connections between thoughts and experiences that form your memories. Research has shown that deep sleep is essential for this process to occur, and that memory impairment is more likely with insufficient sleep.

Insufficient sleep is linked with a variety of health problems, including heart disease and diabetes. Lack of sleep can also contribute to weight gain and lead to depression. It can also decrease your alertness and impair your reaction time, making it more difficult to drive a car safely or make decisions on the fly.