Some of the self damage is due to sensory problems. I will scratch myself bloody often. I don't even realize I do it. I just start scratching when I am stressed. I HAVE to keep my nails as short as possible. That is the only way I keep from having to deal with lots of overly scratched skin and blood.

Try to redirect punching to punching bags or pillows.

I sometimes have to touch parts of my head hard to keep me focused when sensory input is causing me troubles. My head is usually not the problem (most often it is my legs), but for some reason touching points on my head keeps it under control. The standard cranial points taught by the OT are not the ones I have to press. If I touch the recommended points I will fall from the huge burst of pain.

Meditation class might help children who haven't learned yet how to self deal with sensory input. Sometimes just having friends and family telling me to take a deep breathes helps me to reset.