Then he needs to see a doctor. I don’t believe any non-Lubavich Rov in the world will accept that one can consider not having tzaar as the cause of tzaar that patters one from a sukkah.
The real Shaalah is if psychological stress counts as Tzaar. Did you see anyone discussing this question?
Another practical Nafka Minah – someone lives in a safe neighborhood but is paranoid that he’s going to be mugged, so it’s extremely hard for him to fall asleep in the Sukkah. He has no psychological medications on him. Is he Chayav to sleep in a Sukkah? What if he’s in such a state that had this been his house, he would have left and moved into a next door bunker? Is he still Chayav to sleep in a Sukkah?