In the past, such a physiological reaction was helpful if you suffered a sword wound. But engineers are not fighting against an opponent, and they just can't shut off the fight-flight response. At the scene of an accident, the trainmaster is in charge. He gets together with the crew and tries to set up a debriefing. But we at least try to speak with the crew over the phone before the debriefing.
Counselors caution the crew against numbing the pain.
We tell them not to go home and have a stiff drink. We also caution them to eat frequent meals, small amounts of nutritious food. The digestive processes shut down for a time after stress, and these symptoms can go on for days. It's part of the fight-flight syndrome. One guy went home and his wife had cooked a big spaghetti dinner.