Any activity you could give him to substitute for that behavior? Knot-tying like boy scouts or sailors learn, rope-braiding, something that will keep his hands busy witha repetitive motion, but be quiet enough so he can do as he's falling to sleep. (And rope/yarn is soft enough to not hurt if ya roll over on it ...)

My Dad was neither ADHD or OCD as a kid. He was, however, an asthmatic only child, who had trouble keeping still when he should for breathing's sake. My grandmother (his mom) taught him how to chain stitch crochet, which was something you can do and rip out, do and rip out, etc., etc., all with one piece of yarn.