I have mild Aspergers and I do rock back and forth, but I didn't start doing it until I was 12 or 13. It felt really good for whatever reason I was doing it, but people who saw me doing it would always be like, "What's with the rocking back and forth? Are you Autistic or something?" and back then, I barely knew what Autism was. Now that I have been diagnosed, I feel more comfortable doing it whenever I feel like it, but I'm in control..I try not to do it so much around people so I don't freak them out. But if I had my way, I would do it all the time even for just no reason at all because it just feels good.