I definitely believe bipolar is a spectrum disorder. At one end you have cyclothymia, then Bipolar Not Otherwise Specified, which is kind of a wastebasket diagnosis that means "you probably have BP, we just don't know which kind". Then you've got BP 2 and BP 1 on the other end. I like to think that my own case of BP 1 isn't as severe as a lot of people with the same diagnosis, but with my manic episodes plus occasional psychosis, it's too severe to be BP 2. And you don't have to be hospitalized to get the BP diagnosis, no matter which type you have.