Some young children have trouble falling asleep at night. While there may be many reasons for this, my daughter explained one of them as I turned to leave her bedroom one evening. “I’m afraid of the dark,” she said. I tried to relieve her fear, but I left a nightlight on so she could be sure that her room was monster-free.

I didn’t think much more about my daughter’s fear until a few weeks later when my husband went on an overnight business trip. After I settled into bed, the dark seemed to press in around me. I heard a tiny…