I think certain areas of our brain light up when we're hypomanic to manic. It's like when we're depressed certain areas of the brain go dark. What causes it is a mystery to all. Probably brain chemistry and synapse connections. When we are injured endorphins are created or released in the brain, so maybe we have a chemical imbalance or predisposition that when specific incidents (like lack of sleep) occur our endorphins are released en masse. That's my guess anyway. Wish I were hypomanic right now. I have no motivation to work on my projects for my classes. Blah. Good question though. If we knew how it worked and how to trigger it, then I bet most of us would choose hypomania.