that period of high productivity sounds like borderline hypomania (which is often triggered by stress and/or sleep deprivation). did you tend to experience fatigue after those periods of high productivity?
This is the first I've ever heard of hypomania, which I often have in conjunction with sleep deprivation. I also had never heard of Bipolar II disorder.
It's not as dangerous as the kind of mania you get with bipolar 1, but if it occurs to you often, you might want to speak with a doctor. As I understand it, it's difficult to completely control without medical assistance and can have negative effects on your health.
Yes, but these moments were usually followed by an all-nighter. This is my first time hearing of hypomania, but wouldn't the fatigue just be a side-effect of sleep deprivation or the followup of exhaustive mental effort?
Yes. However, one of the side effects of hypomania can be prolonged sleep deprivation/sleeplessness, which creates a pretty nasty feedback loop with days (or more!) of fatigue or outright depression at the end of it.