Ok, I'll give this little plot bunny tag doohickie a try.
I hear about interesting medical stuff from time to time and think of Supernatural, of course.
A doctor did a study between WWII soldiers and their civilian contemporaries with similar wounds and found they had very different pain responses.
""Extent of wound bears only a slight relationship, if any (often none at all), to the pain experienced."
"In a situation in which a wound has great advantage and means escape from overpowering anxiety and fear of death on the battlefield (war wounds terminating military service), extensive wounds are associated with comparatively little pain. In a situation in which the wound connotes disaster (major surgery in civil life), lesser wounds are associated with far more pain than in the former situation. The essential difference appears to be in the difference in anxiety level in the two cases, in the attitude of the patient, and in his reaction to his wound."
These quotes are from
this JAMA article. You can read the full text of the article by clicking an option on the left of the screen.
The Bunny:
I wonder if wee/teen!Sam (the civilian) was ever injured at the same time (or at a later time to the same extent) as Dean or John (the soldiers) and had a LOT more pain than either of them.