[Molasar]

on a serious note, the body has a number of reflex reactions to stimuli like germs, injury, temperature, predators, poisoning and so all of which are in the DNA from millions of years of evolution, those that didn't survive those hazards died off leaving us here now.
(bible-bashers and creationists can fuck off for a minute, this is serious)

your lassitude is a default bodily reaction to a stimulus (in this case electrocution) that we don't have a DNA-coded mechanism explicitly coded in.
give it a million more years (and all of us fucking up by playing with live high-voltage wires and then procreating) and we'll all be grounding 500kV lines with impunity.
well not us obviously, our great-great-.................-great-great grandkids!

Aliantha just sleep it off for a day or two (more if that's what it takes) until your body recovers from its shock and it'll be cool.