Oct. 13, 2003 -- Gastroesophageal reflux and sleep problems go hand in hand. At least 80% of the 60 million Americans who have been diagnosed with GERD report worse symptoms at night, and three in four say they routinely wake up from sleep because of them.
GERD affects more than 20% of Americans with weekly heartburn symptoms.
This association makes sense because when you're awake, gravity helps keep acids needed to digest food down where they belongs -- in the stomach. But when you're lying down, these acids can leak back into the esophagus, damaging its lining and significantly boosting the risk of esophageal cancer.
Some researchers believe that obstructive sleep apnea results in airway pressure changes that can cause reflux to occur, yet other researchers believe that the reflux of acids may result in spasms of the vocal cords that can then lead to sleep apnea.
"With sleep apnea, people tend to breathe harder because their breathing has stopped, and that could induce reflux to flow into the esophagus," says gastroenterologist Ken DeVault, MD, of the Mayo Clinic in Jacksonville, Fla., and spokesman for the American College of Gastroenterology. "It's been thought that this causes reflux to enter the esophagus."
"But so far, it's largely a chicken-and-egg question: Does sleep apnea cause acid reflux, or does this reflux cause sleep apnea by pooling in the esophagus and making it harder to breathe?"
A new study, presented today at the annual meeting of the American College of Gastroenterology, is attempting to find out. And so far, preliminary results from the first part of an ongoing study show that "there may be a casual relationship between reflux and sleep events in people with obstructive type sleep apnea," says lead researcher U.S. Army Major Brian P. Mulhall, MD, MPH, of Walter Reed Army Medical Center in Washington, D.C., in a news release.
"The reflux and apneas aren't consistently occurring at the same time in the patients we've studied, so we suspect they are caused by different mechanisms," says Mulhall.
"Initially, the thought was that it may cause sleep apnea in adults, but we're not seeing a clear relationship between acid reflux and apnea," he tells WebMD.
This is good news for millions of people with GERD, which is most common after middle age, when the valve at the bottom of the esophagus weakens -- making acid more likely to flow upward. The risks for GERD are similar to those for obstructive sleep apnea, and obesity is one reason people develop GERD.
Obstructive sleep apnea is also more common after middle age, especially in obese people. It is caused by relaxation of tissues in the neck, resulting in a temporary obstruction of the air passages. A person with sleep apnea may have as many as 50 or more episodes of breathing stoppage in a single night, raising their risk of high blood pressure and heart attack.
Mulhall's preliminary results do show what researchers have long suspected: reflux does cause people to wake up from sleep. Yet it may be a reflux of other backflowing liquids and not just stomach acids.
So far, the first stage of his study involved 50 adults, 30 of whom have been diagnosed with sleep apnea. Of those, 10 also have GERD. The next phase of his research will involve 280 patients, who will also be evaluated with a new test that measures all contents that flow into the esophagus, including non-acidic liquids that may produce fewer symptoms.
This is important because if the next phase of his research does show a stronger association between sleep apnea and any type of refluxed material, doctors may be better able to help prevent possible esophageal damage in patients not previously recognized to be at increased risk. For instance, it could be the amount of liquids that are regurgitated, not necessarily its acidity level.
"Many patients with obstructive sleep apnea have no symptoms of heartburn," Mulhall says. "What we will be doing is to evaluate whether these patients are having more esophageal injuries than are expected. It may turn out that if you have obstructive sleep apnea, you need to be examined for reflux -- even if you have no symptoms of GERD."