Sleep consists of a series of distinct cycles and stages that restore and refresh your body and mind. Even minimal sleep loss takes a toll on your mood, energy, efficiency, and ability to handle stress. If you want to feel your best, stay healthy, and perform up to your potential, sleep is a necessity, not a luxury. Learn what happens when you’re sleeping, how to determine your nightly sleep needs, and what you can do to bounce back from chronic sleep loss and get on a healthy sleep schedule. I need to sleep! But i can't. Its been 2 days now.