Once I decided to undereat while travelling. The result was that for the first month I was in hypomania almost, very excited about things and places. I also slept much less and kept away from easy pleasures. At some point, at the end of the month, this hyper-functional system broke down, and I realized that though I thought I was dancing, in a club, I was actually not taking my feet of the ground. I suspected I might be tired, and went to bed. 17 hours later I woke up. I interpreted that as "I put myself in emergency mode and became more interested and productive, still this nitro didn't get me the nourishment I needed after a month, so the body gave up and sent a message to the mind (or the medial prefrontal cortex) saying - That was all you had. Give up now, hope for a better crop tomorrow."