My P-Doc told me that Bipolar, OCD, and obviously GAD are all branches of the "anxiety" tree....hence why when one acts up, they all do. I agree that sleep issues can trigger episodes, but so can traumatic events, caffeine (for some), getting lax on meds, etc.
People always say Bipolar is a mood disorder, but I fine that minimizing and a bit offensive. Because to the rest of society, you're just, "Moody," and that's your only problem...i.e., you're just obnoxious to be around and it doesn't affect any other aspect of your life. But it involves so much more than moods.
Anyway, that's my two cents.