That would be unnerving, alright, with the sock moved like that. I used to be scared by nightmares, but then I realized that, for me, it just meant that my body was telling me to wake up and go to the bathroom. After that, I was appreciative of them. And it was nice to go back to sleep. Brains are mysterious and complicated things! Thanks for sharing your experiences!
Brains sure are @haphazard-hstead.
I can buy that the phenomenon is a fabrication of the mind with the cause being abnormal brain activity. However, to this day, I cannot explain away the perfectly balanced damp sock draped over the curtain rod which was positioned less than a foot away from the ceiling.