Phantoms

Bismillah,

Do you guys get them too?? You know, episodes of unexplainable, ridiculous, irrational fear or sadness that no amount of rationalizing can make go away, until they suddenly disappear.

What are they and what causes them?
It's so weird, like.. having a nightmare while you're awake, except you can't break free until someone wakes you up. That's actually how it happens, when I get engaged in conversation they disappear.