We have all been told, probably countless times, to be sure to get a good night’s rest. This advice starts with a child preparing for a busy day at school, an athlete getting ready for a big game, or an adult struggling with life stressors and medical problems. So what exactly defines that phrase, “a good night’s rest”? The answer requires attention to many variables as well as consideration of lifestyle characteristics that apply only to you. It is impossible to get that good night’s rest without first determining how much sleep your body needs.