Edgar Allen Poe once said, "Sleep, those little slices of death. Oh how I loathe them." When asleep the mind changes in ways that are not fully understood, and the purpose of sleep is still largely a mystery. All of us have experienced dreams, both good and bad whether we remember them or not. But can your dreams actually kill you?
There have been many reports throughout time of people having a series of recurring nightmares and ultimately dying in their sleep of various causes, but often the dreams they are having are determined to be a factor in their deaths. Wes Craven's film Nightmare on Elm Street, for example, is not entirely fabricated out of nowhere. It was, in fact, based on a series of stories about people dying from their dreams in southeast Asia. There is even a syndrome called Sudden Unexpected Nocturnal Death Syndrome that has killed over a hundred people in the United States since 1977. Most of these were immigrants from the Vietnam Laos, Thailand, and Burma regions known as the Hmong. The condition is very rare, and there are tests to determine if someone is at risk for Sudden Unexpected Nocturnal Death Syndrome (Also known as SUNDS). But is the phenomenon of sudden deaths while sleeping with no known cause so easily explained by just a rare disease?
One urban legend tells of a girl who was haunted in her dreams by a dead friend of hers who she had wronged in life. The dreams became more vivid as time went on and the girl avoided sleep at all costs even at the expense of her own health. Eventually her parents had her taken to a hospital where tests were done and she was determined to be in good health, but suffering from severe lack of sleep. Against her will she was administered drugs to help her sleep and she died that night in the hospital. The official cause of death was labeled as fear. The story has been told and retold countless times. While it's impossible to determine its origin, it is typical of the 'dreams scaring people to death' line of stories.
So what is there to the theories of dream death? Despite the fact that the phenomena is recorded throughout history, there hasn't been much aside from the identification of SUNDS (which is more of a definition than an explanation) and the claims that sleep apnea may be the cause of some of the cases. In reality there is no way of knowing what someone had been dreaming just before they died.
The terrifying concept was even used in popular culture with the Nightmare on Elm Street series. Craven had based the character Freddy Krueger on stories he had heard of unexplained deaths from dreams, and a homeless person he had encountered when he was eleven that broke into his apartment building. Later he would have terrifying dreams of the strange homeless man. Of course in his case these dreams would be no more than dreams.