It's more of both mental and emotional, as it's a mental disorder in which they effects your emotions as going from "happy" to "mad" real quick in transition.
Same thing for depresion, it seems that people try to claim that they have these "disorders" more so then not, just to get a buzz off of medication or get some extra money during tax time. Which is messed up considering there's actual people who do have this disorder.
Don't argue with idiots because they will drag you down to their level and then beat you with experience.
There are two types of the Bipolar disorder. Type 1, and type 2. I only remember [some] of type 2 though.
Type 2 is when you have a hypomania episode and then a depression episode. I think something has to trigger it though.