Yes, but it usually only lasts a day. I chalk it up to a temporary biochemical issue. When I am down, I usually just think to myself that it is temporary and that it will all be better tomorrow. And it almost always is. Sometimes eating a good dinner makes all the difference in the world (which makes me think it's because I haven't eaten well, not just for no reason).
Other than that, I am surprisingly even keeled, sometimes freakishly so. My wife, while concerned when I had a small breakdown late at night several years back, was a bit relieved. Her thoughts were along the lines of, "Thank God he's human."
Interestingly, if my wife had a bad day, it usually makes my day turn bad as well. I have this tendency to absorb her negative emotions almost immediately, and it makes me a bit distressed. I think this plays into the affective empathy / distress space that many with AS apparently have higher levels of than most people.
_________________
"That leap of logic should have broken his legs." - Janissy