M.P.
My daughter did this too, and I think you're right that they don't really know they're doing it. I put her hair in braids as much as possible, not only to keep her from twisting but also to keep me from having to unravel the knots. I did keep her hair short- not pixie short, just short enough that it was easier for me to get out the knots. She asked if she could have long hair like a princess, and I told her only if she stopped twisting, and by golly she did! But I don't know what I would have done otherwise. Do try the braids, though- my daughter looked really cute with her little braided pig-tails.