My mother lost her sense of smell after surgery for nasal polyps in her teens. She was mortally afraid of fire breaking out in the night and not being able to smell it.
I've woken up at night to investigate weird smells. Maybe the smell didn't wake me up, or maybe it didn't wake me up quickly, but I smelled the smell as I was waking up and then did the find the vaguely burning smell game. Last one I remember was a neighbor's bonfire left going when they went to sleep inside.