Kristin asks: My medical issues have to do with the female lead who has reverse fight-or-flight reactions. When under extreme stress or in fearful situations her heart rate slows and her breathing becomes shallow sometimes to the point of passing out (at least once in the story). I tried to Google this condition and found almost nothing about it. The only reason I’ve heard of it is because one of my best friends has it.
Jordyn says: I think what you’re looking for is called a vasovagal reaction. It can be the body’s response to stress/fear. I don’t know that I would classify it as opposite the fight-or-flight but I can see how someone may have explained it this way to your friend. It can be brought on by seeing something traumatic (extreme emotional stress, seeing bloody things). What occurs is that the vagus nerve is stimulated, which leads to a drop in the heartbeat (bradycardia), which leads to less blood flow to the brain, which leads to passing out.
This is a very common cause of fainting (syncope).
Here’s a couple of references: