But sleep isn’t just essential for the brain. “Sleep affects almost every tissue in our bodies,” says Dr. Michael Twery, a sleep expert at NIH. “It affects growth and stress hormones, our immune system, appetite, breathing, blood pressure and cardiovascular health.”Research shows that lack of sleep increases the risk for obesity, heart disease and infections. Throughout the night, your heart rate, breathing rate and blood pressure rise and fall, a process that may be important for cardiovascular health. Your body releases hormones during sleep that help repair cells and control the body’s use of energy.
These hormone changes can affect your body weight.“Ongoing research shows a lack of sleep can produce diabetic-like conditions in otherwise healthy people,” says Mitler.Recent studies also reveal that sleep can affect the efficiency of vaccinations. Twery described research showing that well-rested people who received the flu vaccine developed stronger protection against the illness. A good night’s sleep consists of 4 to 5 sleep cycles. Each cycle includes periods of deep sleep and rapid eye movement (REM) sleep, when we dream. “As the night goes on, the portion of that cycle that is in REM sleep increases. It turns out that this pattern of cycling and progression is critical to the biology of sleep,” Twery says.