I read somewhere about a child who was afraid of monsters at night, so the parents got a small tent with a zipper and allowed them to pitch it in their room. The child felt safer having the zippered space.

There's a wonderful book called "The Monster Trap" by Dean Morrissey, with Stephen Krensky. It's beautifully illustrated by Mr. Morrissey. I purchased it before my son was born because I recall being afraid of monsters, and enjoyed the ingenuity "Pop" used to calm the fears of his grandson.