This is actually an event that happened to my father. When he was a youngster, probably around ten or twelve, his cousin and him were sleeping on a fold-out couch downstairs in the living room. While everyone else was sleeping, my father happened to see the medal bars in the window pane light up witch looked like a flow of electricity in it.
The electricity (possibility, it was electricity) formed into an electric ball of some sort, then it floated across the living room towards the thermo-stat and somehow, in a way, entered it and everything in the house went silent, the air-conditioning went off and the lights, just everything. After everything came back on my father and his cousin looked at each other with amazement asking , "Whoa did you just see what I saw?".
They both happened to see the same thing, but here's the twisted part, my great-grandfather just happened to have died a week or so earlier, and my father's cousin told him that he thought he saw their grandfather's face on the supposedly "floating ball". To this day, I try to solve whether if it was electricity or a possibility of my great-grandfather saying his last goodbye to the living.