I am not a neuroscientist, so can not answer your question about possible
damage. However, I'm a Clinical Hypotherist and I'd like to suggest that
if you are really worried about this, you CAN stop doing it. You can
learn relaxation through either Self-Hypnosis training or through
Meditation training. A good clinical hypotist can also help you change
the idea that you can't change.
Probably, it would be a good idea to be checked out by a neurologist to
make sure there really isn't anything physical. If that's ruled out,
then it's a habit and habits CAN be overcome.
