I've experienced it once for the first time about 4 months ago, but it lasted less than a day, then just made my depression worse then ever when it was gone. It was great though, I remember thinking that if this is how most people feel most of the time then no wonder people see suicide as such a bad thing. I don't know how to describe the feeling, but it made me think life is worth living for a little while longer to try to get it back.