Background: Nightmare(NM) and its various names is a well known phenomena In different societies. The synonyms (Bangungut) in Philippine is colloquially and culturally used to describe this phenomenon (NM). This enigma is called Sudden Unexplained Nocturnal Death Among Adults (SUNDS) in USA, (pok kuri) in Japan, in Arab countries its name is gutham or khapoos. There is a strong a link between Bangungut (NM) and SUNDS, but SUNDS scientifically as a medical term does not mean nightmare or Bangungut .This paper focused on the enigma of Nightmare, and explores the risk factors which triggers NM (Bangungut) which might lead to death (SUNDS). Objectives: 1. To clarify (explain), the exact meaning of: Nightmare, Bangungut, SUNDS. 2. To determine the risk factors of NM (Bangungut), which might lead to death (SUNDS). 3. To explain the death mechanism of nightmare (Bangungot). 4. To postulate the mechanism, and criteria for diagnosis of NM (Bangungut).