On the outside, I usually seem low-energy mainly because most of my energy is spent in frenetic analysis. But I've noticed that my energy level depends on the situations I'm in. If there is a deadline involved, for instance, I'll be very energetic and be focusing mostly (not solely, unfortunately) on what needs to be done. This is very tiring though, so as soon as I finish sparkling, I revert back to being a low-energy electron. If on the other hand, there is no deadline, I'll be outwardly relaxed but my mind will be drifting.
The energy level, to me, is constant. What differs every time is the amount I show and the amount I don't show, or even how I show it. Hmm it's sounding a bit like the law of conservation of energy now.