I have had recurring bouts of depression since childhood. Never mania, always just depression, all of my life. I was a quiet, introverted and shy kid and remain shy and quiet as an adult.
Except for the time when I was prescribed antidepressant drugs. Within a very short time, I was not sleeping well and I was bouncing off the walls with newfound energy. Trouble was, I was getting sleep deprived and tired of all the energy spent on being wired. Doc said I should be taking sleeping pills as well.
That is when I stepped up to the plate and stopped the antidepressants, and the symptoms of mania went as well.
It has been about 20 years later, and I take no drugs for depression. I try other things like going for a walk and trying to eat well. My depression always subsides with time and a bit of effort. Each episode I come out of more knowledgable about what worked for me.

I believe I would have received a false diagnosis of bipolar back when I was taking the drugs. The drugs themselves caused my mania. Mania has never returned and I seem to be dealing ok with the depression on my own.