“The majority of children do not like to sleep in total darkness or with the door closed, and I see no reason why they should. There is no advantage in trying to train your child to sleep completely in the dark. It will be helpful if the bedroom is dimly lit by a nightlight, a hall light, or even streetlights, so that when your child wakes up at night, especially after a dream, she can reorient herself within the room, re-establish a sense of reality, and put the dream in its proper perspective. And with the door open, she may feel less isolated and alone. So if your child has some anxieties at bedtime or after nighttime wakings, she may get some assurance from being able to see about her room. With the door open, she will not feel shut off from everyone else is the house.

For some children, the fear of “shadows” is the same as that of monsters. Again, you may try to alter the lighting pattern in the room, but once you find a reasonable one, stick to it. Turning lights on and off or moving them around the room each night will do little to allay your child’s fears. If she falls asleep with a particular light on at bedtime but becomes frightened on waking during the night and finding the light off, you should leave it on all night.”

—Dr. Richard Ferber, from Solve Your Child’s Sleep Problems
Fireside Books, Simon and Schuster, 1985