I've also noticed this. When i am very tired and want to sleep, i try and WILD. I have never been successful with the WILD method as i don't quite understand the method fully as yet. But what happens is i lay there peacefully, without any visulization and after a while, i begin getting a sort of dizzy feel sort of like how u have explained with the rolling. However i cannot focus on that feeling long enough and lose concentration. i will try your method as it seems like it will help sustain that sensation.

I do remember, when i had my first proper lucid dream, I was hit with that same sensation and i had become lucid. I believe there is some link between becoming lucid and that rolling sensation. Will post and update if i have success