Is sleep apnea deadly? What the research says

Severe untreated sleep apnea is linked with a higher risk of dying earlier, mainly from heart and blood vessel disease. In the research, that risk shows up over years of follow-up, and it's concentrated in severe cases. Mild sleep apnea showed little or no extra risk in the biggest studies. Sleep apnea is very treatable, and treatment clearly helps people feel and function better.

Is sleep apnea deadly?

Sleep apnea can be serious, but for most people it isn't deadly in the way the question suggests. Large long-term studies link severe untreated obstructive sleep apnea with a higher risk of death from any cause and from heart disease. People with mild sleep apnea didn't show a clear increase in risk.

Cleveland Clinic lists several complications of sleep apnea that can be severe or life-threatening. These include heart rhythm problems such as atrial fibrillation, high blood pressure, heart damage and heart failure, sudden cardiac death, and daytime sleepiness or microsleeps that are dangerous while driving.

An American Heart Association scientific statement explains why the heart is involved. Sleep apnea causes repeated drops in oxygen, swings in the nervous system's control of the body and broken sleep. The statement estimates that about 34% of middle-aged men and 17% of middle-aged women meet the criteria for sleep apnea, and that it's present in 40 to 80% of people with high blood pressure, heart failure, coronary artery disease, atrial fibrillation and stroke. It also notes sleep apnea is often missed in heart care.

So the honest answer is that sleep apnea is a risk factor worth treating, not a sudden danger most people need to fear tonight.

What do long-term studies show about sleep apnea and death?

Long-term studies show that severe sleep apnea is linked with higher mortality, while mild sleep apnea is not clearly linked. The Sleep Heart Health Study found a 46% higher risk of death with severe sleep apnea. The Wisconsin Sleep Cohort found about three to four times the risk with severe untreated sleep apnea.

The Sleep Heart Health Study followed 6,441 men and women aged 40 and older for an average of 8.2 years, after an overnight home sleep test. After adjusting for age, sex, race, smoking, weight and existing health conditions, here's how the risk of death compared with people without sleep apnea:

The study found that oxygen drops during sleep, rather than broken sleep, were independently linked with death. Deaths from coronary artery disease followed a similar pattern. Our guide to what AHI means explains the severity scale.

The Wisconsin Sleep Cohort followed 1,522 adults for 18 years after an in-lab sleep study. Compared with people without sleep-disordered breathing, those with severe sleep-disordered breathing had three times the risk of death from any cause. When the researchers left out the 126 people who had used CPAP, the risk rose to 3.8 times for death from any cause and 5.2 times for death from heart and blood vessel disease. These results held after accounting for daytime sleepiness, so people with severe sleep apnea who don't feel sleepy weren't spared the risk.

Both studies are observational. They show a link, not proof that sleep apnea causes every extra death, though the researchers adjusted for the main factors that could explain it.

Can sleep apnea cause sudden death at night?

Sleep apnea may raise the risk of sudden cardiac death during sleeping hours. A 2005 study of 112 people who died suddenly from heart causes found that 46% of those with obstructive sleep apnea died between midnight and 6 a.m., compared with 21% of those without it and 16% of the general population.

That pattern is unusual. In the general population, sudden cardiac death peaks between 6 a.m. and noon and is least common between midnight and 6 a.m. For people with sleep apnea, the study found the relative risk of sudden cardiac death in the midnight to 6 a.m. window was about 2.6 times higher, and it rose with sleep apnea severity.

A later study from the same group followed 10,701 adults who had a first sleep study between 1987 and 2003, for an average of 5.3 years. During that time, 142 had sudden cardiac death, either fatal or resuscitated, an annual rate of 0.27%. The strongest predictors were age over 60, an AHI above 20, and low oxygen levels during sleep. The lowest overnight oxygen reading was linked with risk independently of well-known heart risk factors.

To keep this in proportion, sudden cardiac death was uncommon even in this group of people referred for sleep testing, and age and existing heart disease were also strong predictors. The finding is a reason to take sleep apnea seriously, particularly if you already have heart problems, not a reason to fear going to sleep. Our article on snoring and heart health covers related research.

Does treatment lower the risk of dying?

Treatment improves symptoms clearly, but whether it lowers the risk of death or heart events is less certain. Observational studies found fewer fatal heart events in people using CPAP. The largest randomized trial, SAVE, found no reduction in heart events, though average CPAP use was low.

The observational evidence is encouraging. A 2005 study followed men for about 10 years. Those with untreated severe sleep apnea had 1.06 fatal cardiovascular events per 100 person-years, compared with 0.35 in men treated with CPAP and 0.3 in healthy men. After adjusting for other factors, untreated severe sleep apnea was linked with almost three times the odds of a fatal cardiovascular event compared with healthy men. The authors concluded that CPAP reduces this risk, but because people chose whether to use CPAP, the groups may have differed in other ways.

The SAVE trial tested this more strictly. It randomly assigned 2,717 adults aged 45 to 75 with moderate to severe sleep apnea and existing heart or blood vessel disease to CPAP plus usual care or usual care alone. Most were men with little daytime sleepiness. After an average of 3.7 years, heart and stroke events happened in 17.0% of the CPAP group and 15.4% of the usual care group, a difference that wasn't statistically significant. Average CPAP use was only 3.3 hours a night.

SAVE did find clear benefits in how people felt. CPAP significantly reduced snoring and daytime sleepiness and improved quality of life and mood.

A 2023 analysis in JAMA pooled individual data from SAVE and two other trials, 4,186 people in all. Overall, CPAP didn't lower the risk of repeat heart and stroke events. But in people who used CPAP for at least 4 hours a night, the risk was 31% lower. The authors concluded that how consistently people use CPAP may be the key factor.

So the evidence suggests that CPAP helps most when it's actually worn for much of the night. That's why your sleep team cares about mask fit and comfort. Our overview of sleep apnea treatment options covers CPAP and the alternatives.

What else makes untreated sleep apnea risky?

Untreated sleep apnea also brings risks beyond the heart, and drowsy driving is the most immediate. Cleveland Clinic notes that daytime sleepiness and microsleeps from sleep apnea are dangerous while driving or operating machinery.

The AHA statement also recommends checking for sleep apnea in people with high blood pressure that's hard to control, pulmonary hypertension, and atrial fibrillation that keeps coming back after treatment. If you have any of these, it's worth asking your doctor whether a sleep study makes sense. Our articles on sleep apnea and driving and sleep apnea and high blood pressure go into more detail.

Does having insomnia as well change the risk?

Having insomnia as well as sleep apnea may add to the risk. A 2022 analysis of 5,236 people in the Sleep Heart Health Study found that those with both insomnia and at least moderate sleep apnea had a 47% higher risk of death over 15 years than people with neither condition.

People with both conditions also had higher rates of high blood pressure and heart disease when the study began. Only about 3% of participants fell into this group, and like the other cohort studies, it shows a link rather than proof of cause. Both conditions are treatable, and our article on sleep apnea and insomnia explains how they're treated together.

What should you do if you're worried?

If you're worried about sleep apnea, the most useful step is getting a diagnosis. Cleveland Clinic says a provider will ask about your symptoms and medical history and, if they suspect sleep apnea, recommend testing. That's usually an overnight sleep study in a lab or a home sleep apnea test. Snoring, gasping at night, pauses a partner notices and daytime sleepiness are all worth mentioning.

The sleep study measures how often your breathing is disrupted and how low your oxygen drops. Those details matter, because the research above suggests that severity and oxygen levels shape the risk. Our list of sleep apnea warning signs and our guide to home sleep apnea tests can help you get started.

If you've already been diagnosed, keep using your treatment and tell your sleep team if it's hard to stick with. The AHA statement recommends follow-up sleep testing to check that treatment is working. And if you ever see someone who can't breathe or can't be woken, call emergency services.

Read next

• Sleep apnea and driving: the risk and how treatment helps
• Sleep apnea and high blood pressure: what's the link?
• Can sleep apnea go away?

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.