Sorry but you always forgot that when you sleep your consciousness disappeared. Please take account for this fact. When all sensory shut down, really you feel nothing and of cos think nothing.
When you actually pass out, there's a very real sense of discontinuity. You find yourself on the floor, unsure how long you've been there (even if it was just seconds), and how exactly you got to that position (the previous recorded memory being you standing there and feeling woozy).
It's very different from just sleeping, where you still retain a feeling of continuity with both place and time.
The claim that consciousness is an illusion has always seemed like nonsense to me; for, if consciousness is an illusion, who experiences that illusion? Answer: the conscious mind.
It's a controversial idea, but depending on the state of the brain, there may be more than one consciousness.
Maybe "you" are actually a committee.
But sleeping people are not even close to being unconscious.
They can dream, and they're aware enough to know they should probably wake up if they're prodded hard enough.
Conveniently this metaphor works at multiple levels.
Not even medically unconscious people are guaranteed to be completely non-sentient. Ask any anaesthetist.
No dreams, nothing. You don't exist during those hours. You cannot account for them later; they are deleted.