We sleep because that's when we are logged out of the virtual game that this world is.
I'm only semi-serious.
But let's work with it. What if we research sleep right until there is nothing left to find out, and we since can't figure out any reason at all for it?
Could we use that to postulate for a reason that is non-physical? Spiritual? Virtual reality? Something else?
Have you never set a game with alerts that make noise if something interesting is happening, so you rush back and play?
The delay in waking up is how long it takes the "player" to get back to his chair.
If the player did not go back that would be seen by us as fainting, or in longer situations, a coma.
Maybe it's just refactoring and caching, and we are full biological systems with no hidden variables in the macroscale.
Because the "you" that is conscious is actually your game player in another world. So it's that "person" that is actually programming. Your body here is basically a robot.
This would also explain why we can't figure out what consciousness actually is - if it's not physically in this world that would make it hard to figure out.
> biologically evolve on the robot
I'm not aware of any multi-cellular organisms at all that don't sleep. None.
So if it did evolve it must have done so in a single celled organism that doesn't sleep, which of course makes no sense. (Why evolve the need for something you'll only need when multi-cellular?)