The aim of this cross-over, randomized, single-blinded trial was to examine 
whether intra-esophageal acidification induces sleep bruxism (SB). 
Polysomnography with electromyogram (EMG) of masseter muscle, audio-video 
recording, and esophageal pH monitoring were performed in a sleep laboratory. 
Twelve healthy adult males without SB participated. Intra-esophageal infusions 
of 5-mL acidic solution (0.1 N HCl) or saline were administered. The frequencies 
of EMG bursts, rhythmic masticatory muscle activity (RMMA) episodes, grinding 
noise, and the RMMA/microarousal ratio were significantly higher in the 
20-minute period after acidic infusion than after saline infusion. RMMA episodes 
including SB were induced by esophageal acidification. This trial is registered 
with the UMIN Clinical Trials Registry, UMIN000002923.
ABBREVIATIONS: ASDA, American Sleep Disorders Association; EMG, electromyogram; 
GER, gastroesophageal reflux; LES, lower esophageal sphincter; NREM, non-rapid 
eye movement; REM, rapid eye movement; RMMA, rhythmic masticatory muscle 
activity; SB, sleep bruxism; SD, standard deviation; UES, upper esophageal 
sphincter.