V.T.
Hi K.,
My step daughter did this at 4 only she would twist it until it got a little know, and then pull it out! She was literally bald on one side of her head. It was a nervous thing, as her parents were going through a divorce. We finally threatened to cut her hair really short and she did not want that at all, so after about 2 weeks of warning her, (she only did it in her sleep) she finally stopped doing it. I spoke with her doctor and it's a condition called "tricotillomilia". That spelling is phonic so don't look it up based on that! Good luck!
V.