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Why Do Some People Die In Their Sleep?

The risk of nocturnal death is relatively low for most people.

Holly Large - Editorial Assistant

Holly Large

Holly Large - Editorial Assistant

Holly Large

Editorial Assistant

Holly is a graduate medical biochemist with an enthusiasm for making science interesting, fun and accessible.

Editorial Assistant

Unmade bed, to the right is a beside table with a switched-on lamp, alarm clock and phone.

There are certain medical conditions that can increase the risk of dying whilst asleep.

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It’s a pretty human thing to think about our mortality, particularly when it comes to the prospect of how it might happen. For some, they might be worried about dying in their sleep – but thankfully, unless you have a particular medical condition, the chance of that happening is relatively low.

There are a number of reasons why someone might die in their sleep, but they usually center on three of our most important organs. "Dying in your sleep is usually related to the heart, lungs or brain," explained Dr Milind Sovani, a consultant in respiratory medicine at Nottingham University Hospitals NHS Trust, speaking to Newsweek.


When we’re asleep, we’re less likely to be able to respond to the signals that might indicate something is wrong with these organs. “If I’m standing up and I have a 10-second pause in my heart rate, I’m going to fall down and pass out and make a big thud and someone is going to hear it,” cardiologist Jack Flyer told The Wall Street Journal (WSJ). “When you’re sleeping, you just can’t respond to yourself and your own symptoms.”

The heart

The most common cause relates to the heart. According to Sumeet Chugh, medical director of Cedars-Sinai’s Heart Rhythm Center, sudden cardiac arrest (SCA) is responsible for 90 percent of sudden and unexpected death during sleep, also known as nocturnal death, WSJ reports. People at higher risk of SCA include those with coronary artery disease, an enlarged heart, or an irregular heartbeat (often one that’s fast, also called ventricular fibrillation). 

SCA is when the heart suddenly stops beating, which in turn stops blood flow to the major organs and can result in death without immediate treatment. Of all such deaths from SCA, 22 percent occur between 10 pm and 6 am, with women more likely to be affected during this time. 


Obstructive sleep apnea (OSA) can also play a role in death during sleep. People with OSA may be more than 2.5 times as likely to experience sudden cardiac death between 12 am and 6 am as those without obstructive apnea. OSA involves a narrowing of the muscles in the airway, briefly stopping a person from breathing. This causes a lack of oxygen and in turn, raises heart rate and blood pressure, which Dr Chugh says increases the risk of SCA.


However, OSA is often not a cause of night-time death on its own. It’s more often related to nocturnal death when it exacerbates another condition, such as a heart problem. 

The brain

Epilepsy is a common condition affecting the brain, in which people experience recurring seizures. For people whose seizures can’t be fully controlled by medication, sudden unexpected death in epilepsy (SUDEP) is the leading cause of death. Although the reasons behind SUDEP are not entirely clear, it often happens at night, and some research suggests that sleep could increase the risk of it occurring. 

Stroke can also be responsible for sudden nocturnal death. Around 25 percent of strokes occur during sleep, and conditions such as OSA may also heighten the risk. They happen when either a clot or ruptured blood vessel stops blood from being able to get to the brain. Without an oxygen supply, brain cells die, and the parts of the body that affected regions of the brain control can no longer function properly, which can ultimately become fatal.

How can risks be managed?

For those with medical conditions that may increase the risk of death during sleep, it is recommended to speak to a doctor, who will be able to take into account factors such as lifestyle and family history. When it comes to everyone else, according to Chugh, the risk of sudden death is relatively low.


To keep that risk low, doctors recommend keeping a general eye on your health, getting enough sleep and exercise, and maintaining a healthy diet. 

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.  


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