I found this website the other day. It's 2 young American guys with Aspergers. I really like what they say about what they call defence mode(or defense mode if you're American!)
it is something I have discovered with my son (he calls it shutdown mode) . I don't think there's enough talk about it.
I remember reading that Temple Grandin says the dominant emotion of autism is fear, and this kind of expands on that.