That sudden, unexpected and utterly relentless dose of depression is exactly what I was talking about in my post: http://www.livejournal.com/users/whiskerfish/94511.html

The worst part about this instant-on depression thing is that the opposite rarely happens. If I am wallowing in one of these low points an instant turnaround is hard to come by.

You and I are amazingly similar in this respect. All extremes and a love for horsepower!