Since I was a child, I enjoyed sleeping in cars and ships, much less in planes for whatever reason.
As an avid SciFi reader, I used to imagine I was sleeping on a starship en route to some distant planet - and still do sometimes.
As for noises, the regular tick of a clock will keep me awake, while I’m soothed by the unpredictable, limping, irregular rhythm of my Vetinari clock - the sequence repeats over several months, so no way it’s predictable, a tick can last from 1/4 to 2 seconds.
Interesting. My brother keeps a small fan running in his bedroom to help him sleep, can’t do without it anymore. I wonder if getting used to having that sound creates a dependency.
When I was little back in the 1970s, my father was already on the pink noise program. He hung a fan in the bedroom hallway. We kids called it “the noisemaker” and couldn’t sleep without it. It ran every night for years. (I think it was the blower unit for one of those old hair dryers with the hose and helmet.)