T.B.
My 4 almost 5 year old just got afraid of "shadows" in his room. He does have a nightlight but shares his room with is 12 year old brother (who prefers it dark).
I found a stuffed animal and added a cape to it and now he's a SuperHero Dog who gets rid of all the monsters in his room. It works sometimes, but not always.
We also have given him a flashlight to use when he wakes up, but he tends to leave it on overnight and burn out the batteries. I'm thinking there must be some with an auto-turn off feature, so I'm on the look-out for one of those to hopefully solve the problem.
Luckily, as with everything else, its just a stage and before too long they will forget about the monsters under the bed and be on to something else.