I have bipolar type 1, so have experienced all levels of mania, including hypomania. As for hypomania, I had many periods in my life when I'd ride at that level for a long time before it ever escalated to full blown, or faded/switched. I've pretty much displayed all of the symptoms of hypomania/mania over time, but lean towards some over others. My hypomanias can be elated, irritable, anxious, and/or mixed with some depressive symptoms. Even within the same episode I may experience more than one of these. It can fluctuate at the drop of a dime, especially with a trigger. Meaning I could be flying on Cloud 9 one second and then turn into a viscous animal, the next.

I believe in the bipolar spectrum theory and that we all have our own "flavor" of the illness. I even think that personality can play a part in the illness presentation. For example, I rarely had hyperspending (I'm frugal by nature) and when I did, it was piddly compared to some peoples'. Impulsivity and disinhibition have been common symptoms in my illness. Yes, I become more sociable, too, but sometimes more "Star of the Show". Gosh, believe me! Grandiosity has also been involved, at times. During all of this, I can be unaware of any negative reactions from people, which there have been. Believe me! Other times, others see me "as a star" or a "sparkling individual", which exacerbates matters as it fuels the flames.

You referenced becoming more involved with things when elevated in mood. I definitely relate as I become very project-oriented. Often I bit off way more than I could chew, in this respect. When my mood fell, I became overwhelmed by what I got myself into. I couldn't maintain the pace, which when hypomanic or manic can be extremely fast.

I have experienced sleep issues when hypomanic/manic, but not nearly to the degree as others. Or when I did, I usually didn't care. More time to "Trip the Light Fantastic".

We all mostly have a "baseline" mood, which could be called "stable". Not everyone's baseline is the same, even among those without a mood disorder. One "normie" (for lack of a better word) can be ultra energetic and exuberant, regularly. A person with bipolar disorder who is low energy and negative as a norm, may be hypomanic when they act like that exuberant "normie". The question is if a person starts to act unlike their norm and seemingly for no good reason or to a surprising degree. People who know them must notice the difference, and sufficient symptoms must be present.