Are you sometimes exhausted during the day, even when you think you've gotten enough sleep? You could be one of an estimated 27 million Americans suffering from nighttime gastroesophageal reflux disease (GERD), a condition characterized by heartburn that can wake you in the middle of the night—often without memory of it the next day.
Then again, you may suffer from obstructive sleep apnea (OSA), a sleep and breathing disorder that affects over 20 million Americans. Sleep apnea occurs when the soft tissue at the back of the throat collapses and blocks your airway, causing you to stop breathing while you sleep. When this happens, you wake up to start breathing again. Apneas can wake people hundreds of times a night without their knowledge.
But what's worse, if you suffer from either GERD or OSA, there's a decent chance that you suffer from both. A number of studies have illustrated that apnea sufferers also often have nighttime reflux and vice versa. What's worse? Suffering from both might make you more tired than either one alone. But doctors don't fully understand the nature of the link between them. Does one cause the other or are they both caused by something else?
"Right now, causal links are speculative," says Dr. William Orr, professor of medicine at the Oklahoma University Health Sciences Center.
Some doctors, like Dr. Yohei Mizuta of the Nagasaki University School of Medicine in Japan, believe that apneas probably cause reflux symptoms. Apneas (and waking up because of them) change the pressure within the lungs and gastrointestinal systems, possibly causing some stomach contents to be drawn up into the esophagus, the tube that connects the stomach with the throat.
Other doctors think it could be the other way around. Irritation of the esophagus due to reflux could cause airway spasms that lead to apneas, and preliminary studies have shown that acid-suppressing drugs for reflux also reduce the risk for sleep apnea.
Then there's the possibility that neither GERD nor OSA causes the other and that something else entirely is to blame. Obesity, for example, is strongly associated with both conditions and may be causing them to appear linked when they're really not.
"It is not clear whether one condition facilitates the other, or whether the relationship just represents the fact that both conditions are associated with obesity," says Dr. Stephen Field, clinical professor at the University of Calgary in Alberta, Canada, in an e-mail. "Most patients will experience an improvement in both conditions if they lose weight."
But it's been difficult to understand the link between OSA and GERD for several reasons. Many people who suffer from nighttime reflux or sleep apnea don't even realize it, so patient questionnaires are often inaccurate. Also, there is no "gold standard" for diagnosing GERD.
"Many patients with GERD disease have a complex of upper gastrointestinal symptoms that do not permit reliable diagnosis from the symptoms alone," says Dr. Robert C. Heading, president of the Association of Gastrointestinal Physiologists, an arm of the British Society of Gastroenterology, in an e-mail.
And this brings us to the good news: When it comes to treatment, the nature of the link between OSA and GERD doesn't really matter. There are ways to reduce common risk factors, and some treatments help to alleviate symptoms of both. Treatment is, in fact, crucial because both conditions can cause serious complications: GERD increases the risk for asthma and some forms of cancer, and OSA increases the risk for heart disease.
So, if you are overweight or obese, losing weight will almost certainly help. Quitting smoking and reducing alcohol intake also reduces the risk of both conditions. And even sleeping on you left side, as suggested by the American Gastroenterological Association, may help to reduce reflux, too.
You can also talk to your doctor about a class of prescription acid-suppressing drugs called protein pump inhibitors (PPIs), such as Nexium and Prevacid. These drugs are effective at treating nighttime GERD symptoms and have been shown to reduce the incidence of sleep apnea.
But by far the most effective treatment for sleep apnea is called continuous positive airway pressure (CPAP), which involves wearing a mask at night that supplies a steady stream of air into the nose. Interestingly, CPAP, which is covered by most insurance plans for sleep apnea sufferers, has also been shown to improve reflux symptoms.
"The fact that CPAP really does seem to work is of considerable interest," Heading says. "But again," he says, alluding to the poorly understood link between sleep apnea and reflux, "No one knows why."