I have no evidence that the hyperbolic figure of speech is literal truth, no. I do have evidence that people in high-stress environments have health complications.
My dad flew 30 some missions over Germany. The cohort he went over with had an 80% casualty rate. Some missons had a 10% death rate. He could do the math, and assumed he was going to die.
(Obviously, he did not die, since I exist, but he came literally within a couple inches.)
When he arrived back in the US, he was bemused by all the stuff back home people worried about. He thought "what the heck are you worried about, you're going to live another day!"
Stress is a physiological reaction to certain stimulus. You can stab people with blood monitors and conclude that yes, it is a high-stress environment.
