Nightmare on Elm Street is the story of a creature with razors for hands that hides in kids' nightmares and tears them to shreds whilst they sleep. In terms of films you want to be based on a true story, it isn't exactly up there with Ratatouille and Shrek 2.
Well sorry to break the bad news, but it is. Director Wes Craven says he came up with the idea after reading a series of articles in the LA Times about healthy young male Southeast Asian refugees who arrived in the US. Then, out of nowhere and with no discernible related health problems, they "cried out in their sleep. And then they died".
The number of people from Southeast Asia who died this way was alarmingly high during the 1980s, with at least 117 cases in the decade after the US authorities started tracking it in 1981. This became one of the top five causes of death among the Laotian Hmong population in the US.
The medical authorities began calling it "Asian Death Syndrome" and later "Sudden Unexpected Nocturnal Death Syndrome [SUNDS]", while in popular culture it took on a number of other names.
“In the Philippines, it’s called bangungut, in Japan pokkuri, in Thailand something else,” Dr Robert Kirschner told the LA Times in 1987. “But it all roughly translates as the same thing: nightmare death."
At the time, the mystery took hold in the wider US population, with authorities just as baffled as everybody else.
''I know what they didn't die of,'' Dr. Michael McGee, assistant medical examiner for Ramsey County, Minnesota, told the New York Times following four such deaths. ''They didn't die of getting shot in the head, stabbed in the heart; they didn't fall off the roof; they didn't get poisoned; because we did an autopsy in each case, and we got a big zero.''
"We didn't think anything mysterious was afoot until the third and fourth deaths happened very quickly,'' he added, ''but then we began to wonder."
Further autopsies of 18 of the victims found that all of their hearts were enlarged, and 17 of them had defects in their conduction systems that initiate and coordinate muscle contractions of the heart. Dr Friedrich Eckner of the University of Illinois College of Medicine – who conducted the autopsies – dramatically told the Los Angeles Times it was as if “their hearts just shorted out.”
A more systematic look at the deaths took place in 1987, published in the American Journal of Public Health. The research investigated deaths in the US and refugee camps in Thailand, finding deaths of this nature even more prevalent there than in the US. The study focused only on deaths during sleep and took case histories from the patients' family, friends, and fellow refugees within the Thai camps.
In many of the cases, previous instances of sleep disturbances were found. One family found their daughter breathing abnormally and completely unresponsive. Fearing this was similar to reports they'd heard from others, they attempted to wake her, until she regained consciousness minutes later. She died in front of her parents 33 months later after they witnessed similar breathing difficulties. Another saw a 25-year-old man wake up following abnormal breathing, his legs feeling numb and weak. A medical examination came back normal, however: "he died suddenly during a nap at 2:00 pm the same day."
Among the findings – though they admitted part of it could be related to bias favoring recollection of previous deaths in families affected by SUNDS – was that there were higher instances of this type of death within the families of those already affected, as well as higher instances of epilepsy in those who died. This suggests that there is a genetic element to the condition.
"Southeast Asian victims of sudden death in the US tend to be more recent immigrants, compared to controls, indicating that newly arrived refugees in the US may have a greater risk of sudden death than longer-term residents of the same group," they found, in a pattern consistent with the idea that stress was a factor in these deaths.
One professor at the University of California, Shelley Adler, went as far as to claim that the belief in nightmare spirits prevalent among the Hmong population contributed to their deaths – though the condition is most likely a condition of the heart, via the extra stress this placed on them.
Eventually, the likely culprit of the deaths was found, long after Wes Craven had turned the mystery into Nightmare on Elm Street. Brugada syndrome – caused by mutations, most commonly to the SCN5A gene – disrupts the heart's normal rhythm. The inherited condition is believed to explain some cases of sudden infant death syndrome, as well as SUNDS.