Wow so I wasn't imagining this? I started Lithium a little over a week ago and 2 days after I took my first dose, I skyrocketed into euphoric hypomania. I'm a rapid cycler so each of my moods lasts only a week as it is, but usually I have a few days of "normal" mood after depression before becoming hypomanic. This time, I was depressed for only 5 days and then bam, hypomanic. I thought it was just a coincidence since I didn't think the medicine would have effects that quickly. Then again, I also started getting really thirsty after only a few days as well. The difference is my hypomanic episode lasted for its usual time for me instead of ending after a few days like it did for you.