Not sleeping/irregular sleeping patterns can lift my mood in a very short time. If I start getting sleep soon enough, it may go back to normal - but not always.
Stress about money or studies can cause swings both up and down.

Usually when I'm having a good episode, it ends up with me drinking several days in a row, or very much at once. The alcohol throws me straight into depression. Also when I lived at home, my parent's problems were a huge trigger.

But yeah, not sleeping is one of the biggest triggers. Sometimes I have stayed up nights intentionally, just to get out of depression.

EDIT // I forgot to mention that Christmas mostly makes me depressed, and holidays in another city tend to make me very hyped; leading into huge excitement, hyperactivity, restlessness, shopping & spending money and not sleeping.