What ‘Dying in Your Sleep’ Actually Means

Everyone’s heard the phrase “dying in your sleep.” But what does dying in your sleep feel like? Is it really peaceful, like Grandma’s obituary said? What actually happens when someone dies in their sleep?

What dying in your sleep is actually like—i.e., what happens to the body, since we have no firsthand accounts—depends on the true cause of death, of which there are many. Science tells us that, yes, it is actually possible to die a seemingly painless death while remaining asleep.

But what are the facts behind the obituaries? What can actually cause you to die in your sleep? Read on to learn what the phrase really means.

You Died of Cardiac Arrhythmia

What ‘Dying in Your Sleep’ Actually Means

Elizabeth Simpson, reporter for The Virginian-Pilot, decided to investigate the phrase “died peacefully in his sleep” before including the phrase in her own father’s obituary in 2011. Simpson discovered that there is one condition that is most commonly the cause of someone dying in their sleep—and it turned out to be what technically killed her father.

Here’s what Dr. Simone Gold, an ER doctor from California, told Simpson: “If a patient simply dies, without any symptoms, which of course we don’t know unless it is witnessed, but when that is what occurs, absolutely and without question the most common reason would be a cardiac arrhythmia, specifically ventricular fibrillation or pulse-less ventricular tachycardia.” Basically, your heart starts to beat differently than it usually does, which leads to death.

You Died of Carbon Monoxide Poisoning

What ‘Dying in Your Sleep’ Actually Means

Hearing that someone “died in their sleep” might also mean carbon monoxide poisoning. It’s called the silent killer for a reason: an entire family can fall asleep in a house with a carbon monoxide leak and just never wake up.

The CDC says more than 400 Americans die this way each year. It warns that those who are “sleeping or drunk” can die before experiencing a single symptom of CO poisoning.

You Were Electrocuted

What ‘Dying in Your Sleep’ Actually Means

Here’s a weird one: you could “die in your sleep” after being electrocuted. How? Dr. Patrick Lantz, a professor of pathology at Wake Forest University School of  says the conditions would have to be just right. Let’s say there’s a faulty wire in a hairdryer.

Lantz says touching that hairdryer in the bathroom late at night before going to bed could give off a shock, but an irregular heartbeat caused by that shock may not start that second:

“It may give them enough time to lie down on the bed and fall asleep or fall down on the bed. They might not be found right next to the device that caused the electrocution.”

You Died of Central Sleep Apnea

What ‘Dying in Your Sleep’ Actually Means

Researchers at UCLA think a condition called “central sleep apnea” might be behind a lot of cases of elderly people dying in their sleep. It’s so sneaky it can go totally undetected, leading examiners to attribute heart failure as the cause of death instead.

Central sleep apnea typically affects people older than 65 and is caused by losing brain cells that help control your breathing. Older folks with already weak hearts and lungs stop breathing during sleep because of a lack of those cells. They’re unable to rouse themselves naturally and they die from lack of oxygen.

You Died of Sudden Unexpected Nocturnal Death Syndrome

What ‘Dying in Your Sleep’ Actually Means

Sudden Unexpected Nocturnal Death Syndrome, or SUNDS, is an obscure genetic condition that leads to cardiac arrhythmia. It strikes otherwise healthy people while they sleep—some in their early 30s—and it is prevalent in Southeast Asia. At one point in the early ‘80s, in fact, it was in the top five natural causes of death among the Hmong people, many of who resettled in the US after the Vietnam War.

Dr. Shelley Adler, author of Sleep Paralysis: Night-mares, Nocebos, and the Mind-Body Connection, makes the controversial claim that the Hmong died in their sleep because of their belief in night spirits:

It is my contention that in the context of severe and ongoing stress related to cultural disruption and national resettlement (exacerbated by intense feelings of powerlessness about existence in the United States), and from the perspective of a belief system in which evil spirits have the power to kill men who do not fulfill their religious obligations, the solitary Hmong man confronted by the numinous terror of the night-mare (and aware of its murderous intent) can die of SUNDS.

You Died of a Stroke

What ‘Dying in Your Sleep’ Actually Means

A massive stroke can sometimes be the cause of “dying in your sleep,” but according to Dr. Leah Bush, former chief medical examiner of the state of Virginia, you usually would have experienced headaches or other nagging pain before you went to sleep. About one in seven strokes happen while you’re asleep, but they’re not all so-called “wake-up” strokes and are virtually indistinguishable from strokes experienced while awake.

Elizabeth Simpson shared an anonymous journalist’s story about their mother dying of a stroke in her sleep at 82 in The Virginian-Pilot in 2011:

She was physically active and mentally alert up until her final moment. She most likely thought warmly about her granddaughter’s upcoming wedding when she went to bed that night. The TV in her bedroom was still on when her body was discovered the next morning. She was in bed leaning back against a pillow. The remote control was still in her hand.

You Died of a Brain Aneurysm

What ‘Dying in Your Sleep’ Actually Means

Massive bleeding from a brain aneurysm is linked to sudden death during sleep, according to Dr. Patrick Lantz. That’s what killed 22-year-old Aminah Jennifa Ahmed, who didn’t wake up from a nap the day she graduated from the University of Texas in 2015. She vomited on campus after receiving her diploma and once again on the ride home, but her parents chalked it up to stress.

As the director of the school’s Islamic Learning Foundation put it, her poor parents saw “their daughter graduate literally hours before she was declared completely brain dead.”

You Died of Enterovirus D68

What ‘Dying in Your Sleep’ Actually Means

A New Jersey preschooler with no known health problems and no signs of infection died in his sleepafter being infected with Enterovirus D68 in 2014. Eli Waller, 4, went to sleep the night of September 24 showing no symptoms whatsoever, but his family found him dead the next morning. The next day, health authorities determined it was D68.

Enterovirus D68 is spread through “respiratory secretions and excrements” and presents itself as a mild to severe respiratory illness when (or if) symptoms emerge. The CDC says there is no specific antiviral medication available to fight the virus, which most commonly infects kids.

You Died Peacefully

What ‘Dying in Your Sleep’ Actually Means

If someone truly does die in their sleep—meaning no symptoms roused them from their slumber—then doctors agree that they did actually die peacefully. Dr. Simone Gold says dying in your sleep of cardiac arrhythmia—ventricular fibrillation, specifically—is ideal: “If you have to die, this is a great way to go.” Ventricular fibrillation is not a heart attack, she explains, but rather a “short-circuit of the electricity” of the heart, which would cut the flow of blood to your brain, rendering you unconscious.

Compare this to the so-called “agonal respiration” of a patient desperately clinging for life. This breathing can sometimes last for hours, and is a sign of the body struggling to die. This struggle can even occur in a patient technically asleep and medicated with morphine.

It Was Just a Euphemism

What ‘Dying in Your Sleep’ Actually Means

There’s also a possibility that “dying in your sleep” is just a euphemism for a household tragedy (such as carbon monoxide poisoning) or suicide. One anonymous journalist shared the story of their grandfather’s death at 87 with Elizabeth Simpson of The Virginian-Pilot. They were told their entire adult life that their grandfather “died in his sleep,” but that’s not what happened at all:

I was 17 and decided that was how I wanted to go. Twenty-five years later, when my mother was dying of cancer, I learned that, in fact, he had committed suicide. He had cancer and did not want to be a burden to his family. That’s what he wrote on the note that he left for my grandmother and mother, pinned to his pajamas. He was a doctor and evidently had stowed away enough pills for when the time came.