Solution

I get morbid when I'm Really Tired.
I noticed this habit of mine some time ago, generally when I'd think about the conversations from the night before and realize they'd devolved into a sink of introspection and analyzation.
(Note: if you think you're being too introspective, you're probably right.)
So I picked up on this tendency of mine.
A long time ago.
And realizing it never did me much good, since all I did with the realization was to warn my Good Friends During those Really Tired Times: "Hey guys, I'm not really myself when I'm this tired..."
Except guess what. The other night no one was around to say that to.
So I went to sleep early.
And y'know, I'm brilliant. Sleep works wonders.