A child's fear of the dark causes a lack of sleep, which can negatively affect their concentration, mood, motivation, and overtime can harm their overall development. Listening to your child is the first step that can help control their fear. This book is based on my fear of the dark, depicting real-life events using fictional characters. Facts about fear of the dark: Fear of the dark usually begins around age two or three. Fear of the dark can continue into early adolescence. Among eight- to twelve-year-olds, it is the third most common and upsetting fear. Source: Jane Sosland, PhD