Sleep apnea and acid reflux: how they're linked and what CPAP does for heartburn

Sleep apnea and acid reflux often show up together. People with obstructive sleep apnea have higher odds of gastroesophageal reflux disease (GERD), and genetic research suggests each condition may make the other more likely. The encouraging part is that in several studies, treating sleep apnea with CPAP cut nighttime reflux. If heartburn wakes you at night and you also snore loudly or stop breathing in your sleep, it's worth raising both with your doctor.

What is GERD, and how is it different from heartburn?

GERD is acid reflux that keeps happening or causes problems, while heartburn is one of its symptoms. NIDDK, part of the US National Institutes of Health, describes heartburn as a painful, burning feeling in the middle of the chest behind the breastbone. It describes regurgitation as stomach contents coming back up into your throat or mouth, sometimes with a taste of food or acid.

Not everyone with GERD has heartburn. NIDDK lists chest pain, nausea, trouble swallowing, and chronic cough or hoarseness as other possible symptoms. The NHS says reflux symptoms are often worse after eating, when lying down and when bending over, which is part of why nights can be the hardest time.

NIDDK explains that the lower esophageal sphincter, a ring of muscle where the esophagus meets the stomach, normally keeps stomach contents down. GERD can develop when that muscle is weak or relaxes when it shouldn't.

How are sleep apnea and acid reflux linked?

Sleep apnea and acid reflux are linked in pooled studies, though how one affects the other isn't fully worked out. A 2023 meta-analysis in the Journal of Gastroenterology and Hepatology combined six studies with 2,950 patients and found an association between sleep apnea and GERD, with an odds ratio of 1.53. The link held after the researchers accounted for sex, body mass index, smoking and alcohol. Interestingly, among people with sleep apnea, having GERD didn't change how severe their sleep apnea was as measured by AHI.

Observational studies can't show which condition comes first. A 2023 study in Frontiers in Genetics tried a different approach called Mendelian randomization, which uses genetic variants as a stand-in for a condition to test cause and effect. It drew on genetic data from 27,207 people with sleep apnea and 280,720 without, plus a genetic study of GERD covering 602,604 people. It found evidence that sleep apnea raised the odds of GERD (odds ratio 1.19) and that GERD raised the odds of sleep apnea (odds ratio 1.44). That points to a two-way relationship, though genetic methods like this rest on assumptions of their own.

The two conditions also share risk factors. The NHS lists obesity, alcohol and smoking among things linked to sleep apnoea, and lists being overweight, alcohol and smoking among things that can cause or worsen heartburn. Some of the overlap is likely explained by these shared causes.

What happens in the body?

The exact mechanism isn't settled. One question researchers have looked at is whether each breathing pause sets off a reflux event directly. A small 2011 study in Sleep and Breathing tested this. Researchers measured breathing, esophageal pressure and acidity overnight in eight people with sleep apnea and nighttime reflux.

They found no direct relationship between individual breathing events and reflux events. What they did find was that the pressure barrier at the lower esophageal sphincter was low in these patients. Off CPAP, the group averaged 2.7 reflux events and 70 obstructive breathing events an hour. The authors suggested that repeated strain from obstructed breathing might weaken the junction between the esophagus and stomach over time. On CPAP, the lowest barrier pressure during sphincter relaxation tended to be higher, and the relaxations were shorter. With only eight people, this is a clue rather than an answer.

Does CPAP help acid reflux?

CPAP has reduced nighttime reflux in several studies of people with sleep apnea. The largest single study, published in Archives of Internal Medicine in 2003, followed 331 people diagnosed with sleep apnea. Before treatment, 62% had nighttime reflux. Everyone was prescribed CPAP, and at follow-up the researchers compared people still using it with those who had stopped.

Scores ran from 1 (never) to 5 (always). Follow-up reached 181 of the 204 people who had reflux at the start. People on higher CPAP pressures tended to improve more, with a strong correlation between pressure and improvement. The comparison group was small and not randomly assigned, so the result isn't conclusive on its own.

A 2021 meta-analysis in Sleep and Breathing pooled 10 studies with 272 participants. After CPAP, people spent less time with acid in the esophagus, had fewer reflux events and shorter longest episodes, and scored better on reflux symptom questionnaires. The improvement was clearer with longer treatment. The authors concluded that CPAP significantly reduces reflux events in people with sleep apnea.

CPAP is a sleep apnea treatment, not a reflux treatment, so keep any reflux medicine your doctor has prescribed. The NHS says not to stop prescribed medicine without speaking to a doctor first. If you're starting out, our guide to getting used to CPAP can help, and sleep apnea treatment options covers the alternatives.

What does this mean if you have both?

If you have both conditions, treating them together makes sense, and neither treatment replaces the other. The research suggests a few practical points.

First, if you have reflux that wakes you at night and you also snore, gasp or feel unrefreshed, a sleep test may be worth asking about. The 2003 study found nighttime reflux in 62% of people with sleep apnea, so the overlap is common.

Second, if you've been diagnosed with sleep apnea and started CPAP, give it time before judging its effect on reflux. The 2021 meta-analysis found improvements were clearer with longer treatment, and the 2003 study looked at people who were still using CPAP at follow-up.

Third, don't expect reflux to make your sleep apnea worse on paper. In the 2023 meta-analysis, people with sleep apnea and GERD had a similar AHI to those without GERD.

What can you do tonight to ease reflux?

Several simple changes can ease reflux at night, and some of them help sleep apnea too.

• Leave a gap before bed. The NHS advises not eating within 3 or 4 hours before bed.
• Raise your head. NIDDK suggests raising your head 6 to 8 inches during sleep with a foam wedge or pillows under your head and upper back. The NHS prefers raising the head of the bed itself by around 10 to 20 cm with wood, bricks or books, and warns that extra pillows alone can increase pressure on your belly.
• Eat smaller meals. The NHS suggests smaller, more frequent meals and avoiding foods and drinks that trigger your symptoms, such as coffee, tomatoes, alcohol, chocolate and fatty or spicy foods.
• Watch the alcohol. The NHS lists alcohol as a heartburn trigger and links it to sleep apnoea. Our article on sleep apnea and alcohol explains why evening drinks matter.
• Lose weight if you're carrying extra. NIDDK and the NHS both list weight loss for reflux, and the NHS lists it for sleep apnoea too. See sleep apnea and weight gain.
• Stop smoking. Both NIDDK and the NHS recommend it for reflux.

If you already raise your head at night for snoring, our guide to sleeping elevated for snoring has more on that. If you also wake with a blocked nose, see acid reflux and a stuffy nose.

Is mouth tape safe if you have reflux?

Mouth tape isn't a good idea while reflux is bringing stomach contents up into your throat or mouth, and it isn't a treatment for sleep apnea. A 2025 systematic review in PLOS One found that four of the ten mouth taping studies it looked at explicitly discussed a serious risk of asphyxiation if the mouth is closed off and there's nasal blockage or regurgitation. If you have sleep apnea, ask your sleep doctor before trying tape at all.

Our guide to mouth tape and acid reflux explains when it may be fine again. We don't recommend mouth tape for children.

When should you see a doctor?

See a doctor if you think you have GERD, or if your symptoms don't get better with over-the-counter medicines or lifestyle changes. That's NIDDK's advice. It also says to see a doctor for chest pain, loss of appetite, persistent vomiting, problems or pain swallowing, vomit that contains blood or looks like coffee grounds, black or bloody stools, or unexplained weight loss.

Ask about sleep apnea too if you have its warning signs. The NHS lists breathing that stops and starts during sleep, gasping, snorting or choking noises, loud snoring, waking up a lot and feeling very tired in the day. A blocked nose that never clears is worth mentioning as well. If you're pregnant, the NHS lists pregnancy as a cause of heartburn and says a pharmacist can advise on medicines you can take; check with your clinician too. Our guide to sleep apnea warning signs explains what to look for.

This article is general information, not medical advice. Talk to your doctor about your own symptoms.

Read next

• Mouth tape and acid reflux or nausea at night
• Can acid reflux cause a stuffy nose at night?
• Sleep apnea and nocturia

* 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.