When I was younger I used Marijuana as a coping mechanism quite often. At the time I didn't know I was Bipolar but it helped quiet my mind and calm my anxiety. It actually worked in a couple different ways depending on whether I was up or down. If I was depressed it made me feel better and I was more social and enjoyed more things but if I was manic...especially at the apex of my mania when I enter extreme anxiety and paranoia it helped calm me down some.

I think if you qualify there's no reason not to give it a go. If it was legal here in Sweden I would definitely ask for it.