I find I have to be more mindful of giving my body physical and mental rest, as it is my habit to be engaged. A Water Fast is giving the digestion a rest and maybe you need to be more mindful of not using this extra energy to expend physical energy, but sort of, let your body recycle it inward to reuse it to restore the whole of your body. That is how I like to think of this, I don't know, this surge of energy you describe. I think we are so used to doing it is hard to just 'be' sometimes. May sleep come soon and deep for you. Elizabeth