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Sleep and Gastroesophageal Reflux

March/April 2008

Clinical studies and case reports have long defined the relationship between acid reflux and sleep disorders in patients with gastroesophageal reflux disease (GERD) as one of simple cause and effect. Recent studies suggest, however, that the association is much more complex.

Investigations of the physiology of sleep, for example, now suggest that sleep can be a catalyst for acid reflux. Studies implicate the reduction of primary peristalsis and saliva production during sleep and sleep-induced relaxation of the lower esophageal sphincter (LES) in precipitating nocturnal GERD injury due to prolonged esophageal contact time in the supine position. On the other hand, postprandial refluxate lingering in the esophagus may provoke reflexes in the airways while reclining, interrupting breathing, disrupting sleep – and shifting the onus of causality back to acid.

"It’s likely that what we’re seeing are reciprocal, corresponding effects," says Geoffrey S. Spencer, MD, who investigated the relationship between GERD and sleep in a recent clinical study. "In this construct, GERD and sleep may play complementary roles in sleep disturbance."

A specialist in acid-peptic disorders at the Penn Digestive and Liver Center, Dr. Spencer examined nocturnal gastroesophageal reflux and sleep in patients with a history of nocturnal GERD and obstructive sleep apnea (OSA), a condition in which 60 percent of patients report abnormal reflux. All patients used continuous positive airway pressure (CPAP), a therapy commonly used to treat OSA. In addition to assessing the efficacy of CPAP in OSA, the study was designed to determine whether sleep disturbances prompt reflux events or vice versa.

Sleep data and pH were recorded on a single instrument using a calibrated transnasal pH catheter and polysomno – graphic monitor. The primary endpoints included percentage of time at pH <4 in the distal esophagus and occurrences per hour of pH <4 for more than 4 sec onds. Independent of the CPAP findings, the study linked sleep disturbances (awakenings and arousals) to exacer bations of GERD, but found no association between reflux and standard sleep events. CPAP reduced nocturnal acid exposure to normal or near normal levels in 73 percent of those with abnormal reflux.

David C. Metz, MD, Director of the Acid-Peptic Program at Penn, provides further insight into the role of sleep in GERD-associated nocturnal events. A longtime investigator of GERD, Dr. Metz observes that some aberrations of sleep—snoring or apnea, for example— may induce a negative intrathoracic pressure sufficient to draw refluxate into the esophagus.

"Studies suggest that sleep impairs esophageal clearance," says Dr. Metz. "Thus, acid introduced into the esophagus during sleep remains in contact with the mucosa for an extended period, worsening the injury and in the process increasing both the likelihood of injury to the esophageal mucosa and of sleep disruption."

The search for a protagonist in sleepassociated injuries attributable to gastric acid seems far from over. A recent study proposes that the volume of nocturnal reflux, independent of acidity, is responsible for obstructing the esophagus during sleep disturbances. Earlier findings, however, indicate that distal gastric acid exposure during sleep enhances proximal migration of gastric contents. Other studies diagram a complex series of actions and reactions over time involving both the gastrointestinal and respiratory systems.

"It’s clear that the relationship between gastroesophageal reflux and sleep needs further investigation," says Dr. Spencer, "but the information we’ve gathered so far and the methodologies we’ve developed for further study suggest that we’re well on the way to that resolution."

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