The Health Benefits of Sleep
Most people know they feel better, both mentally and physically, after a good night’s sleep. But few know that the benefits of a healthy sleeping habit extend beyond boosting brain and body function to repair them on a cellular level, strengthening key systems that help fight disease, improve fitness, and look and feel healthier. In fact, sleep may be the most powerful health behavior of all. Adequate amounts of restful sleep have been convincingly linked to a lower risk for many diseases, including high blood pressure, heart disease, diabetes, obesity and depression.
Scientists have long known that sleep is important for mental and physical well-being, but they are only beginning to understand what it’s about. Sleep is a complex and dynamic process that affects almost every system in the body, from the heart, lungs and muscles to the immune system, hormone production, mood and resistance to disease. The body needs sleep to work, and skipping it can cause problems such as low energy, irritability, trouble thinking clearly, impaired memory, weight gain, increased risk of accident and illness, and more.
In a normal night of sleep, the brain shuts down most of its activities and most cells turn off their natural production of energy. The body conserves energy by going into “energy storage mode” during most of the sleep cycle. The brain and nervous system use a reserve of energy from food, which is stored in cells called glycogen cells (see Figure below). This energy is drawn on when the body is active during the day.
During most of the sleep cycle, the brain is quiet, but during the REM phase, the brain’s thalamus sends and receives signals to and from the cerebral cortex, allowing it to create dreams. Dreams are made up of images, sounds and sensations that feel like waking life. The brainstem inhibits the descending motor neurons during this period to prevent acting out the dreams, so the images and feelings remain in the brain instead of becoming actions.
During REM sleep, the brain makes a chemical called growth hormone that helps the body grow, heal and repair itself. It also stimulates the immune system and increases blood circulation to the muscles, skin, intestines and digestive tract. The brain also produces a protein that acts as a stress hormone, helping the body cope with illness and injury. Sleep has many other critical functions that researchers are only beginning to explore. Sleep also allows the brain to prepare for learning and memory, forms new connections, and helps the immune system ward off infections. This is why it’s so important to get enough sleep, and why you should try to make sleep a priority. Ideally, go to bed and wake up at the same time each day, and avoid exposing yourself to light or noise before and during your sleep. Keep a sleep journal to help you remember your dreams. You can find more tips and resources at the National Sleep Foundation website.