I think that's why sleep has been called the 'little death' since ancient times. In a sense, you die every time you sleep, and wake up a slightly different person.

Edit: ya'll have dirty minds. Homer refers to 'sleep as the brother of death' in the Illiad. Apparently Buddha said something similar too, though I can't find a source.

Edit2: just going to leave you with this: "each day is a little life: every waking and rising a little birth, every fresh morning a little youth, every going to rest and sleep a little death." – Arthur Schopenhauer