Most people with bipolar variations do not have mania. Instead they have some level of “hypomania”. Here is an example of how hypomania can change from a positive experience to a very negative one (from a blogger who wrote eloquently about bipolarity, link long gone alas).
First, the positive phase:
Increased energy. A extraordinary feeling of happiness with myself and the world. A very loving feeling towards the people I care about. An uncommon ability to get things done. A huge burst of energy from the moment I awaken until I go to bed. An expanded ability to multi-task. An organizational acuity that is second to none. A willingness to engage with people. A desire to spend more time with people I care about–and even those I don’t.
Then, the negative phase of hypomania (still pretty subtle):
I start feeling burned out. While I still have a lot of energy, I don’t have that “I love the world” feeling. If I’ve been playing my Autoharp at my mother’s assisted living facility, and jumping up and down to help all the participants turn the pages and stay with me, I suddenly feel that the staff should be more helpful in doing this.
… things don’t just slide off my back. While I try not to “snap” back at people, I am not always successful. I am certainly less willing to ignore things that days or weeks earlier wouldn’t have bothered me at all.
I become far less happy, joyful, and kind. I dislike being criticized in any which way.