I'd say it sounds like hypomania, though for me, even though the hypomanic phase can last a long time, it usually gets worse. I end up very delusional (I believe I'm God, and that I'm invincible, and that everything exists just for my benefit), and instead of functioning better, I stop being able to function at all. I'm impatient, quick to anger, and usually destroy my entire life with a devil-may-care attitude.

Just after that is the point when it switches and I crash into depression. And my depressions last, and last... and last.

The switch doesn't flick again until I've climbed back out of the depression, and am nearing normality. Then I get to wave at normal as it goes flying past me on the way back up.