Effect of sleep on gastroesophageal physiology and airway protective mechanisms.

The sleeping state is accompanied by many changes in gastroesophageal function that may be of importance in the pathogenesis of gastroesophageal reflux disease (GERD). At nighttime, gastric acid production is increased, gastric emptying is delayed, esophageal clearance is markedly delayed, and upper esophageal sphincter pressure diminishes significantly. Further, unlike daytime esophageal acid exposure, which appears more easily controlled with medical treatment, nocturnal gastric acid production appears difficult to suppress pharmacologically. Nighttime reflux may be associated with a greater prevalence of supraesophageal reflux symptoms as well. At the same time, protective airway reflexes may limit esophageal reflux in some patients. Derangements in the protective mechanisms should be elucidated, as these might account for susceptibility to GERD in patients with nighttime reflux.