I’ve talked to several other people who’ve had this happen to them before: you’ll be lying in bed, almost asleep when a cat will jump lightly onto the bed. The cat walks around the bed, often over you. However, your door is shut, and there’s no cat in the room! Has it happened to you, too?
I assume that the feeling of the cat roaming over the bed is a hallucination during a stage of sleep so light you don’t realize you’re not awake, but why do people rationalize it as being a cat instead of another animal, or even something else? Would people who have never had cats think it was something else? Why would one even have a hallucination while not-quite-awake? I guess it could be the ghosts of long dead cats, occasionally haunting one’s bed
Hypnogogic hallucinations are not uncommon; a sort of very vivid dream while half-awake. I’ve had them myself. However, I suspect the “phantom cats” effect is due to the more mundane explanation that people who own cats get used to their cat’s nightly wanderings about the bed, and start to anticipate and expect it to the point that they think they feel the cat walking around when the cat is nowhere near. In retrospect, during the times when I have thought a cat was on the bed when one wasn’t, the “steps” were far less distict than when a cat actually was there.
As for why cats and nothing else, well, if a big dog is on your bed, you know it. Catssteps are light enough that they can easily be imagined (usually; my Thunderkitty just bolted across my desk, upsetting a drink onto the floor and stepping on the keyboard and managing to open “Microsoft Help”). I think it highly unlikely that “phantom cats” are ever reported by people who have never owned cats, but I suspect anyone who has had a small, unobtrusive animal that likes to get on their bed has imagined the animal was there once when it wasn’t.
I assume it’s quite similar to the “falling” dream. When you have those, it feels so real!!! It’s like a sort-of tactile hallucination, and yes you can have hallucinations when you’re part asleep. That’s when most people have them according to Carl Sagan in his book The Demon Haunted World.