In 1984, Wes Craven introduced the world to one of the most iconic horror films of all time: A Nightmare on Elm Street. His creation of Freddy Krueger as a demon who kills teens in their dreams was heinous, terrifying and literally ripped from the headlines.

Craven found inspiration for the landmark horror film through an article that was published in the L.A. Times. He recounted the story of a refugee child from the Cambodian genocide, who was terrified to sleep for fear that he would be attacked in his dreams and never wake up.

“When he finally fell asleep, his parents thought this crisis was over. Then they heard screams in the middle of the night,” Craven told Vulture. “By the time they got to him, he was dead. He died in the middle of a nightmare.”

The story Craven described wasn’t an isolated incident: dozens of Southeast Asian refugees in America died for unknown reasons in their sleep during the 1980s. The mysterious deaths were usually among young men in their 20s and 30s from the Hmong ethnic group, and affected a large enough segment of this population to alarm public health experts.

The people suffering from this puzzling ailment were typically refugees from Laos, a small, landlocked country in Southeast Asia. The Hmong minority group had been persecuted in Laos after they were recruited by the CIA to fight North Vietnamese soldiers during the Vietnam War. More than 30,000 Hmong soldiers helped the U.S. fight communism in the northern highlands where they lived, but died at a rate 10 times higher than their American counterparts.

In 1975, the Vietnam War ended, and Laos became a communist country. The new leadership there viewed the Hmong as traitors for their work with the United States. Many survivors from the war fled their homes after the war to become refugees in Thailand or the U.S.

It was a “forced migration under the most trying of conditions,” says Dr. Khatharya Um, Associate Professor at UC Berkeley and author of Southeast Asian Migration: People on the Move in Search of Work, Refuge, and Belonging. “It was a very long journey and a very treacherous journey.”

The group’s troubles did not end with resettlement, as they often remained traumatized by their experiences back home. “These are people who had endured a great deal and had been subjected to a great deal,” Um says. Hmong refugees in the U.S. suffered from high rates of poverty and soon, a mysterious ailment seemed to befall them.

Like Freddy Krueger’s targets in A Nightmare on Elm Street, many of the afflicted were teenagers and young men. Headlines such as “Mysterious Fatal Malady Striking Hmong Men” and “Night Deaths of Asian Men Unexplained” ran in the L.A. Times throughout the late 1970s and early 1980s, any one of which could have sparked Wes Craven’s imagination.

One 1981 article describes the scene of a Laotian refugee who relocated to the U.S. from a refugee camp in Thailand with his family. But shortly after settling in his new country, 47-year-old Yong Leng Thao died in his sleep with his wife beside him, in tears. He was the fourth Hmong man to die while sleeping in nine months—and the 13th nocturnal Hmong death recorded since 1978, according to the article.

Investigators could find no medical explanation for the deaths, but many community members attributed the deaths to chemical nerve agents that refugee soldiers of the Vietnam War would have been exposed to. That theory was not supported by doctors, however.

“Nerve gas doesn’t act this way. There’s no evidence,” said Dr. Larry V. Lewman, county medical examiner, in the L.A. Times article. “Secondly, if it was nerve gas, why does it affect only males and why only during the night?”

Other Hmong believed they were being punished by the spirits of their ancestors for leaving their homeland. Their anxiety centered around “the inability to do right by your ancestral spirits because you’re not there, or because you don’t have the right things to perform the right rituals,” says Dr. Um. “I do think that for many of the Hmong of that generation, the traditional explanation remained salient, if not more salient, than explanations related to cardio-vascular problems.”

The fatal ailment, later classified as Sudden Unexplained Nocturnal Death Syndrome (SUNDS), has been investigated by the Center for Disease Control at length. However, the wave of SUNDS deaths among Southeast Asians, particularly the Hmong group, is still unexplained.

Dr. Um suggests the years of stress that the Hmong endured could be a factor in the disease. “Was that a reflection of what kind of stressors that come with being forcibly removed from a familiar world to a completely alien and sometimes even hostile context?” she asks.

The threat of this mysterious death sentence given to Hmong refugees may be even more frightening than the fictional serial murderer that it inspired.