When Death Comes by Night: Reasons and Causes of Dying in Sleep

Cardiorespiratory Failure, Strokes, and Sleep Disorders May Contribute

People die in their sleep for many reasons, including cardiac and respiratory failure
People die in their sleep for many reasons, including cardiac and respiratory failure. Graciela Vilagudin/Getty Images

In ancient Greek mythology, Sleep was the twin brother of Death, children of the personified Gods of Darkness and Night. It seems there has always been an association between sleep and death. When people die in their sleep, it seems like a peaceful and almost idealized way to pass. Why do people die in their sleep? Explore some of the most common causes and how sleep disorders like sleep apnea, snoring, and insomnia may contribute to a higher risk of never waking up.

When Death Comes in the Night

We spend one third of our lives asleep, so it should be no surprise that a lot of people die in their sleep. There is an important difference between dying overnight (especially when healthy) and dying when unconscious in the latter stages of a fatal disease. Older people and those who are sick who die draw less scrutiny than the young.

Depending on the setting of the death (home versus hospital versus assisted care facility), the death may be commented on by a physician. Rarely would an autopsy be performed (or indicated) unless unusual circumstances are present. This evaluation may be more likely in younger adults or children who die suddenly in the community without known illness.

Even an autopsy may be unrevealing. The cause of death may not be clear. The death certificate may note non-specific reasons: “cardiorespiratory failure,” “died of natural causes,” or even “old age.” Family and friends may be left wondering what happened, and it can be helpful to understand some of the causes of death that occur in sleep.

Setting Aside Trauma, the Environment, and Substances

In some cases, death occurs due to some sort of external factor, either directly from the environment or another outside agent. For example, an earthquake that collapses a building may lead to a traumatic death in sleep. Carbon monoxide poisoning from faulty ventilation and a poor heating source may contribute.

Homicide can also occur during sleep, and murders may occur more often at night.

Medications that are taken to treat medical disorders, including pain and insomnia, may increase the risk of death. This may be more likely if these drugs are taken to excess, such as in an overdose, or with alcohol. Sedatives and opioids may alter or suppress breathing. Painful conditions like cancer, for example, may require levels of morphine that accelerate the process of dying by slowing respiration.

Let us assume natural, internal causes are the cause of death and focus on the most likely culprits.

Focusing on Failure of the Heart and Lungs

It may be helpful to think of causes of death in terms of a “Code Blue” that may be called in the hospital setting. When someone is dying—or at imminent risk of dying—there are a few codependent systems that are usually failing. Most often, the failure of the function of the heart and lungs are to blame.

Evolving respiratory failure may gradually impact the function of the heart and other systems.

Acute decline of cardiac function, such as with a massive heart attack, quickly impacts blood flow to the brain and may, in turn, lead to rapid respiratory failure. The lungs may also quickly fill up with fluid as part of pulmonary edema in heart failure.

When evaluating the causes of dying in one’s sleep, it can be helpful to explore causes that impact these two interrelated systems:

Cardiac Arrest

There is considerable evidence that cardiac function may be stressed during sleep. Rapid eye movement (REM) sleep, in particular, may redline the system with increasing risk towards morning. There also seems to be a circadian pattern of cardiac dysfunction, with problems often occurring late in the night and near the time of waking.

Heart attacks occur when a blood vessel (or coronary artery) supplying the muscle tissue becomes obstructed and the tissue supplied is damaged or dies. These myocardial infarctions may range from minor events that slightly compromise function to catastrophic blockages that lead to the heart’s complete failure as a pump. If blood cannot be circulated, the other systems of the body quickly fail and death ensues.

The heart can also experience irregularities that impact its electrical system. The charge that is required to fire off the muscle in a synchronized fashion may become disrupted. The contractions may become irregular, too fast or too slow, and the heart’s pumping effectiveness may be compromised.

Arrhythmias may be a frequent cause of death during sleep. Asystole is a cardiac arrest rhythm when the electrical activity of the heart cannot be detected. Atrial fibrillation or flutter may undermine cardiac function. Similar ventricular rhythms, including ventricular tachycardia, may become fatal. Cardiac blocks affecting the electrical pattern may also lead to heart dysfunction and death.

Chronic, congestive heart failure (CHF) may also gradually lead to the failure of the heart. Left-sided heart failure quickly impacts the right side of the heart, leading to fluid accumulation in the lungs (with shortness of breath, especially when lying down) and swelling in the feet and legs called peripheral edema. If the heart experiences volume overload, its ability to circulate blood may cease.

Importantly, the heart may affect other systems that rely on its ability to circulate blood. Most notably, an irregular heart rhythm may lead to a clot that travels to the brain and causes a stroke. High blood pressure, or hypertension, may increase the risk. If a stroke impacts the brainstem, breathing, eye opening, muscle control, and consciousness may be compromised. These strokes may be fatal and can occur in sleep.

Respiratory Arrest

Lungs complement the function of the heart and like a team, if one system acutely fails, the other is likely to follow in short order. Pulmonary disease is often chronic, and the impacts may develop more slowly. When a critical threshold is reached, however, death may occur.

At the most basic level, the lungs are responsible for the exchange of oxygen and carbon dioxide with the environment. When they do not function properly, oxygen levels fall, carbon dioxide levels rise, and dangerous changes in the acid-base balance of the body can occur.

Acute obstruction, such as choking on vomit, may lead to asphyxiation. Though unlikely, it is also possible for an obstructive sleep apnea event to prove fatal.

Respiratory failure may occur due to chronic, degenerative disease. This can be the failure of the lungs themselves, such as in:

  • Chronic obstructive pulmonary disease (COPD)
  • Emphysema
  • Cystic fibrosis
  • Lung cancer
  • Pulmonary fibrosis
  • Pneumonia
  • Status asthmaticus
  • Pulmonary embolus (clot to the lungs)

It is also possible for the lungs to fail due to changes in the muscles or nervous system, such as with amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease) or myasthenia gravis.

There are even congenital disorders that affect the ability to breathe like congenital central hypoventilation syndrome. Sudden infant death syndrome (SIDS) represents a failure to breathe normally during sleep.

When death approaches slowly, there is a characteristic pattern of breathing that occurs. It is called Cheyne-Stokes respiration. It is often noted in heart failure, narcotic medication use, and injury to the brainstem. It may indicate imminent breathing cessation and death. Consciousness may become depressed as the affected person slips away.

Considering Other Causes and the Role of Sleep Disorders

It is possible for death in sleep to occur due to a few other disorders, including some sleep conditions. In particular, seizures may be fatal. There is a condition known as sudden death in epilepsy (SUDEP) that is not fully understood.

Obstructive sleep apnea may exacerbate other medical conditions that may ultimately be fatal. These include strokes, heart attacks, heart failure, and arrhythmias that can all result in sudden death.

It is possible to die from sleep behaviors called parasomnias. Sleepwalking can lead someone into dangerous situations, including falling out of windows from upper floors, off a cruise ship, or wandering onto the street into traffic. “Pseudo-suicide” describes fatalities among people with sleepwalking injuries who die without known depression or suicidal ideation.

REM sleep behavior disorder may lead to a fall out of bed and head trauma in sleep. This could cause an internal hemorrhage; an epidural hematoma can quickly prove deadly.

Even if the sleep disorder is not immediately fatal, there is evidence that insomnia increases the risk of suicide. Chronic sleep deprivation may increase overall mortality after years of poor sleep.

In order to avoid dying in the night from a sleep disorder, be aware of other symptoms (including insomnia and early morning awakenings) or signs of sleep apnea (pauses in breathing, snoring, nocturia, bruxism, excessive daytime sleepiness, mood and cognitive problems, etc.). Fortunately, sleep disorders are treatable. Optimize your overall health and don’t forget the important role of healthy sleep.


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Jeyaraj D, et al. “Circadian rhythms govern cardiac repolarization and arrhythmogenesis.” Nature, 2012; DOI: 10.1038/nature10852.

Kryger MH, et al. “Principles and Practice of Sleep Medicine.” Elsevier, 6th edition, 2016.

Shepard JJ. "Hypertension, cardiac arrhythmias, myocardial infarction, and stroke in relation to obstructive sleep apnea." Clin Chest Med 1992;13:437-458.

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