Being afraid of the dark may seem crazy, but this fear is very real for many young children. The fear is so real that kids often carry this fear into their grade school years and in extreme cases adulthood. The first step in dealing with this typical childhood fear is to sooth your child and express understanding.
I personally know how nutty bedtime can become when a child is afraid of the dark. I'm currently watching my four year old anxiously get to bed and though her fear of darkness is hard for her to articulate it's there and makes bedtime a time of resistance.
The fear of dark usually develops in toddlers when they begin to establish a sense of imagination and fantasy before they're able to decipher what's fantasy and what's reality. According to WebMD, "The best thing a parent can do for a child with a fear of the dark is to communicate, be respectful, and show that you understand." Limit TV usage and books with scary content. We don't often register how books and TV can feed into a child's fear, but they very often do.