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FRIDAY, Sept. 25, 2009 ( — If you have heartburn, you may want to think twice before taking a sleeping pill for insomnia. A prescription sedative at bedtime may lull you into dreamland, but it may also increase your nighttime exposure to stomach acid, possibly damaging the cells lining the esophagus.

In a new study, researchers at Thomas Jefferson University Hospital, in Philadelphia, found that people taking the popular sleep aid zolpidem (Ambien) snoozed through nighttime reflux instead of arousing from slumber for the second or two it takes to swallow. Swallowing is the bodys natural defense against the backwash of stomach acids that can bathe the esophagus at night.

“[Swallowing] protects your esophagus because you neutralize the acid with saliva, which is rich in bicarbonate,” explains lead author Anthony J. DiMarino Jr., MD, the William Rorer Professor of Medicine at Jefferson Medical College and the chief of the hospitals Division of Gastroenterology and Hepatology.

Thats true for people diagnosed with gastroesophageal reflux disease (GERD), a condition characterized by persistent acid reflux, as well as people who experience only occasional bouts of heartburn.

The study, which was funded in part by AstraZeneca (which makes heartburn drugs), appears in the September issue of Clinical Gastroenterology and Hepatology. One of the coauthors of the study, Karl Doghramji, MD, the director of the Sleep Disorders Center at Thomas Jefferson University Hospital, serves as a consultant to Sanofi-Aventis, the maker of Ambien.

Over time, acid can damage the esophagus

Donald O. Castell, MD, a professor of medicine at the Medical University of South Carolina, says the study is “extremely important” for GERD patients. “It sends a definite warning that serious levels of acid reflux can occur without detection after a sleeping aid, and that the prolonged acid exposure has the potential to produce injury to the esophageal lining that might not otherwise occur,” he says.

If left untreated, long-term acid reflux can damage the cells lining the esophagus, leading to a precancerous condition known as Barretts esophagus, which, in turn, increases the risk of esophageal cancer. Although the study showed that sleeping pills might increase nighttime exposure to stomach acid, its not clear if they increase the risk of Barretts esophagus or other conditions. (Ambien is only recommended for short-term use.) The study was also relatively small, the researchers note, and it only looked at acid reflux for two nights.

However, it may be the first study to systematically examine the effect of taking a sleep aid on nocturnal acid exposure, says Dr. Castell, who was not involved in the study. “In this sense, a good nights sleep may be dangerous.”

More than 40% of Americans have GERD, which occurs when the muscle between the esophagus and stomach is weak or relaxes inappropriately. This allows the acid contents in the stomach to back up, or “reflux,” into the esophagus, typically causing heartburn and other symptoms. About one-third of Americans have insomnia, and 15% have used prescription or over-the-counter medications to help them sleep.

[ pagebreak ]Acid reflux lasted much longer

In the study, Dr. DiMarino and colleagues recruited 16 GERD patients and eight people without the condition who served as controls. Each person participated in two nocturnal sleep studies. During each study, the participants were hooked up to catheters that measured the pH levels in their esophagus, in order to measure reflux. Then they were sent to the Jefferson Sleep Lab, where they were monitored throughout the night.

The investigators used a “cross-over” design in which the participants received the sleeping pill and a placebo. But no one—not even the investigators—knew in which order the drugs would be administered to a particular subject.

Among the 23 people who completed the study, bouts of acid reflux roused people 89% of the time if they were taking a placebo, but only 40% of the time when taking a sleeping pill.

In the eight control subjects, acid reflux lasted a little more than a second, on average, when they took a placebo. On the nights they took a sleeping pill, the acid reflux event lasted 15.7 seconds.

In GERD patients, acid reflux lasted an average of 37.8 seconds on a placebo, versus 363.3 seconds—more than six minutes—when they took the sleep aid.

“It means that in patients with GERD who have sleep issues, that their management needs to be addressed in a heightened way if they are in need of these type of sleep aids,” says Philip O. Katz, MD, the chairman of the division of gastroenterology at Albert Einstein Medical Center, in Philadelphia, who was not involved in the study.

How you can limit acid reflux at night

If you experience nighttime reflux, talk to a doctor about your symptoms. He or she may want to adjust your medications. Experts also recommend trying these nighttime techniques to help reduce acid reflux:

  • Avoid eating three to four hours before bed
  • Elevate the head of your bed 4 to 6 inches

Dr. DiMarino advises primary-care physicians to use caution when prescribing sleeping pills to GERD patients. “Beware, because they may not be adequately suppressing the acid,” he says. “If you just willy-nilly go out and write a prescription for a sleeping pill in that setting, I definitely think youre setting [patients] up for complications.”