It’s tough to associate creativity with mental illness because obviously if you’re very ill, it gets in the way. … But one of the theories now is that the terrible swings of the mental illness – of bipolar depression – you get these manic highs, these euphorias, where the ideas just pour out of you. And you need to write them down. That’s followed by this dismal low period when maybe you’re a better editor. Maybe it’s easier for you to focus and refine those epiphanies into a perfect form. … The thinking is maybe the correlation exists because the swings of mental illness echo the natural swings of the creative process.
Ok, by “one of the theories now" I assume he means the one published back in 2006. NYC Psychopharmacologist, Ronald Fieve, MD specializes in depressive disorders, namely bipolar - and wrote all about enhancing the lows and highs in Bipolar II. Since the 70’s, many of his patients have been creative types: writers, directors, actors, fashion designers…etc.