This study investigated the mechanism of gastroesophageal reflux (GER) in 10 healthy volunteers. Continuous recordings of intraluminal esophageal pH and pressure were obtained over two consecutive nights. Subjects remained recumbent except for a standardized meal after 1 hour of basal recording. A manometric assembly with seven recording lumens monitored lower esophageal sphincter (LES) pressure, esophageal-body motor activity, swallowing activity, and gastric pressure. An electrode 5 cm above the LES recorded esophageal pH. Sleep was monitored by electroencephalogram (EEG). Basal LES pressure varied widely among subjects. GER was not related to low steady-state basal LES pressure but occurred during transient episodes of inappropriate LES relaxation. These relaxations were usually spontaneous or followed appropriate sphincter relaxation induced by swallowing. Most GER episodes occurred within the first 3 hours after eating. During the night, LES relaxation and GER occurred only during transient arousals from sleep or when the subjects were fully awake, not during stable sleep. After GER, the esophagus was generally cleared of refluxed acid by primary peristalsis, less frequently by secondary peristalsis. Nonperistaltic contractions were less effective than peristalsis for clearing acid. The study concluded that in asymptomatic recumbent subjects, GER is related to transient inappropriate LES relaxations rather than low steady-state basal LES pressure, and primary peristalsis is the major mechanism that clears the esophagus of refluxed material. The results showed that GER occurred commonly within several hours after a meal and less frequently during the night. Episodes of GER were not related to low basal LES pressure but rather to inappropriate LES relaxation. Peristalsis was the major determinant of acid clearance from the esophagus. During sleep, swallowing occurred mainly during intermittent arousals. Inappropriate LES relaxation and GER never developed during true sleep, only during periods of full wakefulness or sleep arousals. The study also found that primary peristalsis was more effective than secondary peristalsis in clearing the esophagus of refluxed acid. The findings suggest that the main mechanism responsible for acid clearance from the esophagus in recumbent subjects is esophageal peristalsis. The study confirmed that the presence of the sleeve sensor across the LES did not act as a major factor in eliciting GER in normal subjects. The results also showed that the incidence of GER was similar in subjects with and without esophageal symptoms. The study concluded that the main mechanism responsible for acid clearance from the esophagus in recumbent subjects is esophageal peristalsis. The findings suggest that the presence of the sleeve sensor across the LES did not act as a major factor in eliciting GER in normal subjects. The study also found that the incidence of GER was similar in subjects with and without esophageal symptoms.This study investigated the mechanism of gastroesophageal reflux (GER) in 10 healthy volunteers. Continuous recordings of intraluminal esophageal pH and pressure were obtained over two consecutive nights. Subjects remained recumbent except for a standardized meal after 1 hour of basal recording. A manometric assembly with seven recording lumens monitored lower esophageal sphincter (LES) pressure, esophageal-body motor activity, swallowing activity, and gastric pressure. An electrode 5 cm above the LES recorded esophageal pH. Sleep was monitored by electroencephalogram (EEG). Basal LES pressure varied widely among subjects. GER was not related to low steady-state basal LES pressure but occurred during transient episodes of inappropriate LES relaxation. These relaxations were usually spontaneous or followed appropriate sphincter relaxation induced by swallowing. Most GER episodes occurred within the first 3 hours after eating. During the night, LES relaxation and GER occurred only during transient arousals from sleep or when the subjects were fully awake, not during stable sleep. After GER, the esophagus was generally cleared of refluxed acid by primary peristalsis, less frequently by secondary peristalsis. Nonperistaltic contractions were less effective than peristalsis for clearing acid. The study concluded that in asymptomatic recumbent subjects, GER is related to transient inappropriate LES relaxations rather than low steady-state basal LES pressure, and primary peristalsis is the major mechanism that clears the esophagus of refluxed material. The results showed that GER occurred commonly within several hours after a meal and less frequently during the night. Episodes of GER were not related to low basal LES pressure but rather to inappropriate LES relaxation. Peristalsis was the major determinant of acid clearance from the esophagus. During sleep, swallowing occurred mainly during intermittent arousals. Inappropriate LES relaxation and GER never developed during true sleep, only during periods of full wakefulness or sleep arousals. The study also found that primary peristalsis was more effective than secondary peristalsis in clearing the esophagus of refluxed acid. The findings suggest that the main mechanism responsible for acid clearance from the esophagus in recumbent subjects is esophageal peristalsis. The study confirmed that the presence of the sleeve sensor across the LES did not act as a major factor in eliciting GER in normal subjects. The results also showed that the incidence of GER was similar in subjects with and without esophageal symptoms. The study concluded that the main mechanism responsible for acid clearance from the esophagus in recumbent subjects is esophageal peristalsis. The findings suggest that the presence of the sleeve sensor across the LES did not act as a major factor in eliciting GER in normal subjects. The study also found that the incidence of GER was similar in subjects with and without esophageal symptoms.