There’s very little written about it. I was sent a paper or mixed depression by Dr Stephen Stahl. Famous bipolar researcher Hagop Akiskal coined Bipolar IV but it’s not widely known, he wrote a lot about temperament. There’s a few of his papers about the temperaments under bipolar disorders and “hyperthymic” (Hypomanic) is one of the main ones. A hyperthymic temperament spells out a better prognosis for bipolar but it can be confusing for patients and clinicians who don’t know the terms and concepts. It can be mistake for ADHD. Nancy McWilliams in her book psychodynamic diagnosis also has a short chapter on Hypomanic personality and its psychological component. Its main defense of denial (everything GREAT!) which she poses as a pretty severe defense to live under all the time. It can be very destructive as people’s lives are a chaotic and confusing mix of careers, schooling, interests, moving cities, relationships etc that don’t “add up.” Hypomanic people can be cheery and sociable and charming but also rude and irresponsible and irritable. (I’m speaking from my experience.) Hypomanic people, like all bipolar people, can be very creative and if they can get their illness under control they can bring their creativity to fruition. They’re usually the “personality hire” in a workplace.