Specific events in the course of a day can trigger your parent to react as if he's experiencing the actual event that occurred while on deployment. Triggers can include loud noises, a familiar smell, being in crowds, and sudden movements. There may be everyday things that you do that can trigger your parent to have PTS symptoms. If this happens, remember that what you did may have triggered a reaction, but did not cause PTS. Post-traumatic stress results from experiencing a traumatic event and not from things that you do.