Specifically I believe that PTS is in some cases used as an excuse to avoid further involvement in stress situations. This reminds of a film I saw once: Yossarian: Is Orr crazy? Dr. 'Doc' Daneeka: Of course he is. He has to be crazy to keep flying after all his close calls he's had. Yossarian: Why can't you ground him? Dr. 'Doc' Daneeka: I can, but first he has to ask me. Yossarian: That's all he's gotta do to be grounded? Dr. 'Doc' Daneeka: That's all. Yossarian: Then you can ground him? Dr. 'Doc' Daneeka: No. Then I cannot ground him. Yossarian: Aah! Dr. 'Doc' Daneeka: There's a CATCH. Yossarian: A catch? Dr. 'Doc' Daneeka: Sure. Catch-22. Anyone who wants to get out of combat isn't really crazy, so I can't ground him. Yossarian: Ok, let me see if I've got this straight. In order to be grounded, I've got to be crazy. And I must be crazy to keep flying. But if I ask to be grounded, that means I'm not crazy anymore, and I have to keep flying. Dr. 'Doc' Daneeka: You got it, that's Catch-22. Yossarian: Whoo... That's some catch, that Catch-22. Dr. 'Doc' Daneeka: It's the best there is.