How do you know the dreams didn't happen before you were fully anesthetized or when the anesthetic was wearing off?
I've had dreams when sleeping where in the dream several minutes or even hours seemed to pass where something happens at the start of the dream and the rest of the dream is trying to deal with it, such as an alarm going off. When I wake up, I find that the thing that started the dream, such as an alarm going off, is actually happening for real and it just started a few seconds ago.
It seems then that the time experienced in a dream can be much longer than the time actually spent in the dream, and so it is possible that every dream remembered is one that occurred just before waking up.
I've had dreams when sleeping where in the dream several minutes or even hours seemed to pass where something happens at the start of the dream and the rest of the dream is trying to deal with it, such as an alarm going off. When I wake up, I find that the thing that started the dream, such as an alarm going off, is actually happening for real and it just started a few seconds ago.
It seems then that the time experienced in a dream can be much longer than the time actually spent in the dream, and so it is possible that every dream remembered is one that occurred just before waking up.