Yes, it turns out if you die in a dream, you could die in real life. No one tell Freddy.

If you die in a dream, you'll die in real life.

It’s one of those urban legends most of us have heard, the sort of knowledge that gets passed around the playground without being questioned. It was a meme before memes, like the knowledge that Marilyn Manson scooped his eye out with a spoon. Or that Marilyn Manson played Paul in The Wonder Years. Or that Marilyn Manson removed one of his ribs for... reasons. Holy hell, we liked to tell rumors about Marilyn Manson.

In the '90s, those sorts of rumors were pervasive, mostly because the internet hadn’t quite spread across the earth just yet, and fact-checking wasn’t something you could do while on the toilet. Also because they’re easy to believe. They tick some box in our psyche. We want to believe them, so we do. The "dying in your dreams" rumor persists for similar reasons, not because there’s no internet, but because it’s nearly impossible to fact check. Dreams are nebulous and fleeting and, after all, if someone did die as a result of dying in their dream, how could we know?

DREAMS IN WHICH I'M DYING

In order to answer this question fully, we have to first examine how it’s structured. The legend, as I originally heard it, was definitive. If ever you die in a dream, you will absolutely die for real. It wasn’t a suggestion or a could-be, it was presented as irrefutable fact.

On this front, at least, we’re safe. We can say with certainty that dying in a dream does not absolutely result in real death.

Dreams of dying and death are not uncommon, and the fact that people are awake and alive to tell of those dreams pretty definitively rules out a one-for-one relationship. However, if we reframe the question to whether or not it’s possible for you to die in real life if you die in a dream or, even more loosely, whether it’s possible for a dream or nightmare to kill you, the answer seems to be a qualified... yes?

Again, we run up against the limits of our own knowledge, but there are a couple of phenomena that suggest there might be such a thing as deadly dreams.

First, it is possible (though unlikely) for a person to be scared to death. When we’re frightened, the body flings itself into fight or flight mode, which is triggered by a flood of adrenaline. The heart beats faster and blood flow is rerouted to major muscle groups. Particularly in those who are already predisposed, the influx of adrenaline can cause a cardiac event, which could lead to death: An ironic result from a process that is meant to keep us alive when sensing danger.

In short, adrenaline is useful; it can cause increased cognitive ability for short periods of time in addition to increased physical response, giving you the opportunity to escape danger. But it’s also toxic in large amounts, causing damage to the heart, lungs, liver, and kidneys. With regard to the heart, a surge of adrenaline causes calcium to enter the cardiac cells, causing the heart to contract. If enough adrenaline is pumped in, the heart just keeps contracting, you get into an arrhythmia, and die.

Fear is certainly one way to cause these surges of adrenaline, but any strong emotion can do it.

Enter: Sudden Unexpected Nocturnal Death Syndrome (SUNDS).

In 1981, reports of sudden death during sleep began being reported to the CDC. These incidents seemed to be isolated to populations who had recently immigrated from Southeast Asia. Otherwise-healthy individuals, most of them between the ages of 25 to 44 years old, were dying in their sleep.

In total, 117 cases were reported from 1981 to 1988. It seemed, so far as anyone could tell, that their hearts just stopped. None of these individuals had any prior history of cardiac events, and all but one had no family history.

It’s also worth noting that as the years progressed, the number of reported incidents decreased. There was, for all intents and purposes, a temporary outbreak of death caused by, or at least occurring during sleep.

This unnerving pattern was, according to Wes Craven, the inspiration for the first Nightmare on Elm Street film. According to Craven, he’d read a story about a family who’d come to the United States from Cambodia. Subsequently, their son suffered nightmares so severe he feared sleep. When he did eventually sleep again, he died. That story probably sounds familiar to anyone acquainted with the Elm Street films, but it’s also supported by the data. Or at least one interpretation of it.

Night terrors, a sort of half-waking dream state accompanied by feelings of fear and panic, have been observed in cases of SUNDS prior to death. It might also explain why the incidents of SUNDS decreased over time.

According to a paper in the Journal of the American Heart Association, refugees exhibited high levels of depression and anxiety in the early years after relocating to the United States. Those rates dropped off in subsequent years. That anxiety could have triggered night terrors, leading to cardiac events, which ultimately claimed the lives of vulnerable individuals.

It’s unclear, and in fact unknowable, if reported SUNDS cases were the result of dreams in which an individual died, but there is some correlation between parasomnias (sleep disorders) like night terrors, and the sudden onset of death during sleep.

We also know that the mechanisms exist for the heart to be catastrophically impacted by overwhelming emotions, like fear. All of which is to say, while dreaming of death is not in and of itself a death sentence, it probably doesn’t help.

The good news is, maintaining your heart health can help to limit these risks. So, if ever you’re in a dream and something wicked comes your way, run.