Sleep is the point at whic your senses are most numbed from everything around you. A lot of bad things can happen when you sleep, like murder and tryig to eat your pillow. However sleep is 100% essential for human existance. If you don't sleep you will die. If you do sleep you may also die. It's a sort of risk either way.
Sleep however can be a good experience as it can induce dreams in which good things happen like flying and pudding. Equally bad things can happen like dynomite and drowning in a river. Dreams have been known to become reality, but quite recently reality can be reflected in dreams.