Fear of the dark
(重定向自Achluophobia)
The fear of the dark is a common fear or phobia among children and, to a varying degree, of adults. Fear of the dark is usually not fear of darkness itself, but fear of possible or imagined dangers concealed by darkness. Some degree of fear of the dark is natural, especially as a phase of child development. Most observers report that fear of the dark seldom appears before the age of 2 years. When fear of the dark reaches a degree that is severe enough to be considered pathological, it is sometimes called achluophobia, nyctophobia (from Greek νυξ, "night"), scotophobia (from σκότος – "darkness"), or lygophobia (from λυγή – "twilight").