I used to be when I was little. I watched too many shows about demonic possession and was positive that if I was left alone in the dark, the devil would get me 8)
Because of this, I slept with the lights on until I was about 10 I wanna say. I started noticing eye problems around that age and when we went to the doctor, we found out that they were a result of being exposed to so much light. Apparently I sleep with my eyes partially open (only a little bit, definitely not all the way) and your eyes just aren't built to handle light 24/7. They found a line of scar tissue in each eye. He gave me glue to glue my eyes shut at night and I thought, "No effing way."
Around this time my dad moved out and into a condo that was in the city. My bedroom was still light inside, even with the lights off at night. This sort of eased me into sleeping with the lights off and now I've gotten to the point where I can't sleep with them on. Naturally I no longer have any eye problems.
Now I kind of enjoy the dark!