It's not just faux derealisation. Many if not all things we do have a very good reason behind them (even if we don't know it). What we need to try is to do these things in a controlled fashion. Not be scared and let it escalate.

Mania and depression are examples, but also a schizoid and a borderline personality, derealisation. Even catatonia is helpful, if we risk being eaten by a tiger, maybe. Though catatonic movement... I don't know.

Simulating parts of a borderline personality must work (I don't have to, but I don't suppress it either and try to control it more, not fight it). Schizoid traits are part of my schizomania and help to make depression more bearable. Some Stoicism or Buddhism, really.