R..
I had a period when I did that as a kid. My dad got me a little flashlight to keep under my pillow so I could shine when I thought I saw something. I have no clue where to find them now, but he got the kind that you have to squeeze to light so that I wouldn't play with it all night. (fingers would get too tired. lol) I have seen at Wal-Mart little flashlights that are like dinosaurs, you squeeze the handle and the mouth opens, and the light comes out. You might try one of those, and tell him that the dinosaur light 'eats' the monsters.