“Sleep research has produced fascinating findings, but what is still very mysterious to scientists-—during deep sleep the EEG is flat lined-—is why we wake up.”
Deep sleep is when the operating system is shut down.
Changes are made to hardware wiring, to keep open the new paths granted during the waking hours.
The system is rebooted.
The Operating system is loaded, and a myriad of utilities.
Then, the window (eyes) opens and your computer is ready (awake).
Who does that?---the operator is comatose--electrically dead. If there is an auto-reboot in there, it's silent (can't be found.) until it goes to work (sleep spindles.)
Googling while tired can take longer than usual.
(and yes, I know we're not exactly like computers - are we?)
Not all the operating system is shut down.
There is still bare consciousness, bare awareness, the listener when you talk to yourself.
It is possible to maintain this awareness through transition into sleep, which is known as lucid dreaming.
There’s much in human consciousness that defies reduction to software and hardware.