Fears not always a bad thing. The child that fears nothing, scares me. We have a 12 year old daughter that needs to have a night-light along with a 9 year old daughter. Some children are just afraid of the dark, because they cannot see. He may have an active imagination at night when it is quiet in the house and he has time to think. It is nice to have a little light in the room in case of getting up in the night and being able to see. The night-light is his comfort and security.
I can totally understand how it makes you as a parent wonder what is bothering him. I am browsing through the comments exactly for the same issue. My 13 year old cousin has been staying with us the past few months, he will not sleep without the ligths on, every night before bed he searches his closet and we had to put a lock on the closet door just to reassure him. He will go upstairs alone but if he has a choice he will wait for one of us to go up with him. We asked his motehr if he was as scared at home and he is, they also have lived int he same house for 12 years. It makes me think that maybe it has to do with his father's drinking and only seeing him 2 weekends each month or his mothers drinking and dating new men constantly. Do you think a 12 year old boy being afraid of the dark could be caused by underlying emotional and/or mental stress? It really is starting to worry me