I have ADHD and never have pulled my hair out... I had a friend in Middle School that did the same thing with her hair. I don't remember what she had that caused her to do so but I do know when she was on her medication it helped her from pulling out hair. She also wore a bandana on her head to help with the hair pulling.

I cannot speak for that part of the problem because I do not know about hair pulling but I can speak for the ADHD part. I am an adult and still struggle when I am off my medication but I have found things that help me that may help your son as well. EATING A LOT! When I am off my medicine if I eat filling foods through out the day I calm down, immensely. It puts me into a bit of a food coma but also helps me sit still.
Also, my Mom rubbed my back, my hands, and my arms and that would calm me down a lot at night. That helped me all through out my child hood and even still calms me as an adult. She would have to rub for a good amount of time until I truly settled down but eventually I would.

I don't know if it will work for you and your family but it could be worth a try.