From: Brian S <firstname.lastname@example.org>
>1) What exactly is sleep?
The word sleep refers to the events and processes that occur when the central nervous system changes from the several states of wakefulness to the several states of slumber.
>2) Why must we and most other animals sleep?
No one knows completely.
>3) Would an uploaded person need to sleep? an SI? Why
>or why not?
No one knows at all.