Nyctophobia (from Greek νυκτός, nyktos, genitive of νύξ, nyx, "night" and φόβος, phobos, "fear") is a phobia characterized by a severe fear of the dark. It is triggered by the brain’s disfigured perception of what would or could happen when in a dark environment.
Despite its pervasive nature, there has been a lack of etiological research on the subject. The fear of darkness (nyctophobia) is a psychologically-impacted feeling of being disposed from comfort to a fear-evoking state. The fear of darkness or night has several non-clinical terminologies—lygophobia, scotophobia and achluophobia. Nyctophobia is a phobia generally related to children but, according to J. Adrian Williams’ article titled, Indirect Hypnotic Therapy of Nyctophobia: A Case Report, many clinics with pediatric patients have a great chance of having adults who have nyctophobia.