I knew I had a nervous breakdown when I had to leave work for the second time in the same week because my emotional state was so fragile I couldn't handle my work and then later I starting acting irrationally and hearing things that weren't there.
I had to be taken to the hospital and ended up in the "special ward" and drugged to within an inch of my life. Incidentally, this all started because my alcoholic father had just had a nervous breakdown from mixing steriods with alcohol (which he'd been told not to do) and I couldn't handle his lapse of sanity and the stresses of my new job.
So all I can say is that, from my experience, it's one of the scariest places you can go, because your mind basically "breaks" under the strain of the stress, and you're living in a nightmare world.
However, you can come back from the abyss. I still suffer from severe depression, but thank goodness, not anything so severe that I lose touch with reality. Although considering what reality is like these days, I'd like to upgrade mine.:laugh: