What sleep apnea does to your heart

Sleep apnea puts the heart under repeated strain at night. Each pause in breathing can drop oxygen levels, jolt the nervous system and break up sleep, and over years that pattern is linked with atrial fibrillation, heart failure, coronary heart disease and stroke. The American Heart Association says sleep apnea is common in people with heart disease and often goes unnoticed. Treatment clearly helps how people feel; whether it prevents heart events is still being worked out.

What does sleep apnea do to your heart?

Sleep apnea strains the heart through three things that happen with each breathing pause: oxygen levels dip, the nervous system swings into alarm mode, and sleep gets broken up. The American Heart Association's 2021 scientific statement on sleep apnea and heart disease describes exactly this mix of intermittent low oxygen, autonomic swings and sleep fragmentation.

The NHLBI puts it in plain terms. Sleep apnea can cause low oxygen during sleep, and it takes a lot of effort to restart breathing many times a night, which can damage organs and blood vessels. It lists atrial fibrillation, atherosclerosis, hard-to-control high blood pressure, heart attack, heart failure, pulmonary hypertension and stroke among the conditions sleep apnea may raise the risk of.

High blood pressure is often the first link in the chain. We cover it in detail in sleep apnea and high blood pressure, so this article focuses on the heart and brain.

How common is sleep apnea in people with heart disease?

Sleep apnea is very common in people with heart disease. The AHA statement says about 34% of middle-aged men and 17% of middle-aged women meet the criteria for obstructive sleep apnea. In people with high blood pressure, heart failure, coronary artery disease, pulmonary hypertension, atrial fibrillation or stroke, the figure is as high as 40% to 80%.

Despite that, the AHA says sleep apnea is often underrecognized and undertreated in cardiology. Many heart patients don't feel especially sleepy, so the usual warning sign may be missing.

Is sleep apnea linked to atrial fibrillation?

Sleep apnea is strongly linked to atrial fibrillation, an irregular heart rhythm that raises the risk of stroke. In a 2006 analysis from the Sleep Heart Health Study, researchers compared 228 people with severe sleep-disordered breathing to 338 people without it, matched for age, sex, race and weight. Atrial fibrillation showed up during sleep in 4.8% of the first group and 0.9% of the second.

After adjusting for age, sex, body mass index and coronary heart disease, people with severe sleep-disordered breathing had about four times the odds of atrial fibrillation. They also had about three times the odds of a short run of fast rhythm from the heart's lower chambers, and nearly twice the odds of complex extra beats.

The AHA recommends screening for sleep apnea in people whose atrial fibrillation comes back after cardioversion or ablation, the procedures used to reset or correct the rhythm.

Can sleep apnea cause heart failure?

Sleep apnea is linked with a higher chance of developing heart failure, at least in men. The Sleep Heart Health Study followed 1,927 men and 2,495 women aged 40 and over, all free of heart failure and coronary heart disease at the start, for a median of 8.7 years. After adjusting for other risk factors, men with an AHI of 30 or more, meaning severe sleep apnea, were 58% more likely to develop heart failure than men with an AHI under 5. The researchers didn't see the same link in women.

Heart failure can also cause its own night-time breathlessness, which our guide to waking up gasping explains how to tell apart from apnea. The AHA says a formal sleep assessment is reasonable for people with symptomatic heart failure (NYHA class II to IV) who show signs of disturbed breathing in sleep or daytime sleepiness.

Does sleep apnea raise the risk of heart attack?

Sleep apnea's link with heart attack and coronary heart disease is less clear-cut than its link with heart failure. In the same Sleep Heart Health Study, sleep apnea predicted new coronary heart disease only in men aged 70 or younger. Among men aged 40 to 70, those with an AHI of 30 or more were 68% more likely to develop coronary heart disease than those with an AHI under 5. There was no clear link in older men or in women of any age, and the researchers called the overall association equivocal.

The AHA statement adds a practical point. People whose chest pain or heart attacks happen at night, or who have nighttime heart rhythm problems, may be especially likely to have sleep apnea as well.

Is sleep apnea linked to stroke?

Sleep apnea is linked to a higher risk of stroke. A 2005 study in the New England Journal of Medicine followed 1,022 patients who had sleep studies. Those with obstructive sleep apnea had nearly double the risk of stroke or death from any cause, even after adjusting for age, sex, race, smoking, alcohol, weight, diabetes, cholesterol, atrial fibrillation and high blood pressure. The more severe the sleep apnea at the start, the higher the risk.

Stroke is also where the guidance is least settled. The AHA says there is clinical equipoise, meaning genuine uncertainty among experts, about screening and treating sleep apnea after a stroke. Our article on whether sleep apnea is deadly looks at the long-term death data in more detail.

Does treating sleep apnea protect your heart?

Treating sleep apnea clearly improves how people feel, but whether it prevents heart attacks and strokes isn't proven. The biggest test was the SAVE trial, published in 2016. It enrolled 2,717 adults aged 45 to 75 with moderate to severe sleep apnea and existing heart or blood vessel disease, and gave half of them CPAP on top of usual care.

After an average of 3.7 years, the CPAP group had no fewer heart and stroke events: 17.0% compared with 15.4% in the usual care group, a difference that wasn't significant. The trial's own results show why that isn't the whole story. CPAP did reduce snoring and daytime sleepiness and improved quality of life and mood. But people in the CPAP group used it for an average of only 3.3 hours a night, and most had little daytime sleepiness to begin with.

Use seems to matter. A 2023 analysis in JAMA combined individual data from three trials, SAVE, ISAACC and RICCADSA, covering 4,186 people with heart disease and sleep apnea. Overall, CPAP and usual care had similar rates of repeat heart and stroke events. But in an analysis focused on people who used CPAP at least 4 hours a night, good use was linked with about a 31% lower risk. That kind of analysis can't fully rule out that people who stick with treatment differ in other ways, but it's a strong reason to make CPAP comfortable enough to use all night.

The AHA says everyone with obstructive sleep apnea should be considered for treatment, including lifestyle changes and weight loss where needed. It says CPAP should be offered for severe sleep apnea, oral appliances can be considered for mild to moderate cases or for people who can't tolerate CPAP, and follow-up testing should check that treatment is working. Our guides to sleep apnea treatment options and getting used to CPAP can help.

How can you look after your heart if you have sleep apnea?

Using treatment consistently and keeping up with checkups are the most practical ways to look after your heart with sleep apnea. The NHLBI says to use a PAP machine for all sleep, including naps, and to bring it when you travel. It also advises regular checkups to make sure treatment is working, and notes you may need a repeat sleep study if you gain or lose a lot of weight. The AHA likewise says follow-up sleep testing should check that treatment is effective.

The NHS says lifestyle changes such as losing weight, stopping smoking and drinking less alcohol can sometimes help sleep apnoea. Those same steps are good for the heart in their own right. If your mask is uncomfortable, leaks or keeps you awake, the NHLBI says to tell your provider, who can try a different mask, machine or settings rather than leaving you to give up.

Does snoring alone affect the heart?

Snoring without sleep apnea has a weaker and less certain link with heart disease. The evidence above is about sleep apnea, where breathing actually pauses and oxygen drops. Our article on snoring and heart health covers what's known about snoring on its own.

Who should get checked for sleep apnea?

Anyone with heart disease and signs of sleep apnea should ask about a sleep test. The AHA recommends screening for sleep apnea in people with resistant or poorly controlled high blood pressure, pulmonary hypertension, and atrial fibrillation that returns after cardioversion or ablation.

The NHS lists the main symptoms as breathing that stops and starts, gasping, snorting or choking noises, waking up a lot and loud snoring, along with daytime tiredness, trouble concentrating, mood swings and morning headaches. Many people learn about these from a partner. Our guides to sleep apnea warning signs and home sleep apnea tests explain the next steps.

This article is general information, not medical advice. Talk to your doctor or cardiologist about your own heart and sleep.

Read next

• Sleep apnea and high blood pressure: what's the link?
• Does snoring affect your heart?
• Is sleep apnea deadly?

* 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.