I've been thinking how I used to be really afraid of the dark as a child, and outside my bedroom, the landing light had to stay on. I got over it as a teenager, but I sometimes wondered if I was the only one; nobody else in the family was nervous about the dark. There was a time I nearly freaked out when we visited an underground place, and were told to turn our lights out so we could see what the pitch black was like.
What happens in your house, do your DCs have any lights on at night?