I have those thoughts too. Even when I'm stable, I'll have some, but they are more random and don't have that compelling feel. When I'm depressed, they are much more pervasive and.... convincing, for lack of a better word.
Btw, amazonmom, when I first saw the title of your thread, I thought, "huh? Apologize for what???" I think your posts are very helpful -- certainly nothing to apologize for there! :-)