I have known two guys that had the "over night white hair" thing happen. One was a "Ranger/Green Beret" in Vietnam, his story (and he had pictures) black hair one day went outside the wire way north, had two days of extreme action running south fur his life losing several guys. When they got back to forward base, he went to bed black hair and he woke up pure white, everybody around was freaking out and taking pictures. The other was a guy, by grace of God, drove through a massive car accident what he said it was like a Hollywood car crash in slow motion. He served, dodged and under an airbourn car he went under. Finally crashing into a guard rail just past the crash. Same think, went to bed dark brown hair woke up completely white hair and his wife screamed in the morning!