We spend about one-third of our lives asleep. This may sound like a lot of time, but it is not wasted. Our bodies need sleep to stay healthy. Not getting enough sleep, or as we sometimes say shut-eye, can make us sick. The immune system protects the body from diseases and infections. Not getting enough sleep hurts this protective system. The Mayo Clinic is a nonprofit research hospital in the United States. Its website explains that when we sleep our bodies release proteins that support sleep and help us fight infections. They add that infection-fighting antibodies and cells are reduced during periods when you don't get enough sleep.