Hmm... it is powerful for a level 5 power, considering the no-save penalties once the effects are in place. But at the same time, it is a twinedged sword. I'd say that it is about right. Perhaps dropping the backlash to -2 (I've never experienced a down after a high, but then again, my highs haven't been caused by chemical or electrical stimuli). But I don't think it is neccessary.