I’m not sure if hypomanic would be a word used to describe it. Hypo used in the medical field means under, but if he’s an animated guy, and his eyes bulge out a bit, he would have an overactive thyroid gland. I have hypothyroid coupled with hyperparathyroid, and it’s like a double whammy of fatigue all the time.
I think that the term “hypomanic” refers to a “touch” of manic behavior, as opposed to full blow manias associated with severe bipolar disorder.