Sometimes when I'm feeling anxious, I feel some physical symptoms in my chest which seem to correspond to metaphors people use, making me think that these symptoms are universal. For instance, people speak of one's "heart sinking," which is quite easily taken as allegorical -- sinking being a downward motion, and the heart seen as the seat of the self or of the feelings. But sometimes I feel something that can really only be described as a physical feeling in the chest which moves downward, which corresponds to the situation in which people speak of a sinking heart. Is that really where the expression comes from, suggesting that other people feel the same seemingly-abstract physical sensation?
Sometimes when I feel these things I don't always know why and I might have to stop and ask myself why I am feeling this particular sensation. I might feel a sort of "fluttery" sensation, which goes with the feeling of being nervous or unsettled, and which I experience as something similar to low blood sugar; in fact, when I experience it, I have to ask myself, am I having low blood sugar, do I just need to eat something, or am I nervous about something, and if so, what?
Sometimes when I feel very down, it feels like a sort of hollowness in my chest, which might be described as being "heart-sick." It feels literally like an emptiness, something missing, a gap.
Other times when I'm that kind of nervous that borders on scared (stupid as it seems, I sometimes get this in combat in Lusternia) I get a sense like a pressure in my chest, located right beneath the sternum, highly localized (I can put a fingertip on the spot), as if it were pressing outwards; this feeling can last for hours or days, long after whatever prompted it has stopped or at least been set aside, though sometimes going back to whatever it was that set it off and resolving it can make it end (other times it just fades with time). As I type this, I'm having that feeling and have been since the previous night, which started with a stupid little conflict in Lusternia that didn't even lead to combat, and I'm not sure why it affected me more than others do.
Then again, maybe it's just that I physically strained my chest muscles during some of the work I did in the game room recently. There is a feedback loop in our physical expressions of emotion: just making yourself smile, even if you don't have a reason to, tends to lift your mood slightly. Maybe a physical strain or ache can cause me to feel the emotional state that might otherwise have caused a sensation similar to that pain.
These are bigger than just the adrenaline rush effects that one gets from exciting or scary things -- I know what those feelings are like but they are short-term, and I'm speaking of things that last hours or days. (I also get the hand-shakes and similar symptoms during those short-term rushes of adrenaline, but that's perfectly understandable.)
I can't begin to guess whether these things, as repeatable as they are, are real physical things or solely perceptual, and whether they are common to other people. Or if they're where some of the phrases we use for them come from. Mostly I just wish I could make them stop.