True. I remember reading somewhere that the one sense that never completely shuts down and is the first to come on line is our sense of smell.
And while mattress makers would have us believe "tossing-and-turning" while we sleep is bad for us* it's perfectly normal...and necessary. While we sleep our body has us flop around every now and then to keep pressure points from forming: Pressure points -> Bed Sores> Gangrene
*(+ the sign of a crummy mattress which, of course, needs to be replaced by one of their fine mattresses.)
Somewhat off topic, but..
The sense of smell is in the “old” or “primitive” brain. The theory is actually that our brain evolved from olfactory stalks. Also in this part of the brain is the autonomic, survival, functions, including, as you mention, the movement to maintain circulation, in addition to breathing.
Yes, if this part of us ever falls asleep, we don’t wake up. :)