Finally, After eating right and exercising you need to sleep. The average adult needs about 8 hours of sleep per night. Sleep is important because it is a time when your body recovers, and when your immune system is improved. Sleep plays a vital role in good health and well-being throughout your life. Getting enough quality sleep at the right times can help protect your mental health, physical health, quality of life, and safety. The damage from sleep deficiency can occur in an instant (such as a car crash), or it can harm you over time. For example, ongoing sleep deficiency can raise your risk for some chronic health problems. It also can affect how well you think, react, work, learn, and get along with others.