William Dement, one of the leading researchers of the last century and co-discoverer of Rapid Eye Movement sleep, concluded from his fifty years in the forefront of the field that "the only reason we need to sleep that is really, really solid, is that we get sleepy."
Notes Towards a Philosophy of Sleep | Philosophy Now
http://philosophynow.org/issues/91/Notes_Towards_a_Philosophy_of_Sleep
http://philosophynow.org/issues/91/Notes_Towards_a_Philosophy_of_Sleep
