Sleep is a naturally recurring state of mind and body characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings.It is distinguished from wakefullness by a decreased ability to react to stimuli. Sleep occurs in repeating periods, in which the body alternates between two highly distinct modes known as REM and NON-rem sleep, where REM stands for "rapid eye movement".
Babies sleep a lot to gain and build-up energy. Bears sleep all winter (!).
Normal humans sleep some 6-8 hours each night. People with mood disorders sleep very differently. Hypomanic people hardly sleep (2-4 hours) whereas depressed people love to sleep 12 hours or more. Older people have a tendency to take a nap in the afternoon.
Movies: The Big Sleep (Bogart/Bacall), Sleepless in Seatle (Meg Ryan, Tom Hanks).
I know it’s late, I shouldn’t call at this hour.