Ha! Ha! the "rational" versus the "graves" mind. I had that experience 6 months ago, the disease went into remission (or so my doctor thought) and then came back with a vengeance. The T4 levels went sky high while I was almost off the meds and I started having panic attacks:
Simultaneously one part of my mind had complete and irrational fear of death (total fight or flight response, I had to have my wife drive me around in the car, like having to escape the city due to impending doom, being stopped at the traffic lights was terrifying) while another part, my rational mind, was helplessly observing this and worrying that I was going insane. I can laugh about it now but it wasn’t funny then.
