Nighttime Acid Reflux More Frequent During Wakefulness and Light Sleep

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Among a cohort of healthy Japanese adults, nocturnal gastroesophageal reflux (GER) was primarily driven by transient lower esophageal sphincter relaxation (TLESR) and occurred more often when individuals are awake or in shallow sleep.

TLESR is defined by lower esophageal sphincter (LES) relaxation without swallowing and is considered to be the main mechanism responsible for both acid reflux and belching. However, data on the mechanisms underlying nocturnal GER is limited, with only one study examining this connection, published in 1991, conducted in Japan.

“A study using high-resolution manometry (HRM), esophageal pH, and polysomnography to evaluate nocturnal GER found that TLESR was mainly responsible for nocturnal GER in controls,” wrote a group of investigators from the Department of Gastroenterology at Nippon Medical School, Graduate School of Medicine, in Tokyo, Japan. “However, GER was evaluated in a hospital setting, and in-hospital measurements may differ from those in a home setting.”

Therefore, the current study used portable HRM and electroencephalography (EEG), as opposed to HRM and polysomnography, to determine the mechanisms underlying nocturnal GER within a home environment. The study investigated the relationship between sleep depth and nocturnal GER among ten healthy men with no history of reflux, surgery or medication use.

The study was conducted at the Nippon Medical School Chiba Hokusoh Hospital between December 2015 and December 2016 and enrolled healthy male participants with a mean age of 33.2 years.

Participants underwent HRM and esophageal pH catheter placement in the evening and then returned home after a test meal. Sleep depth was monitored using EEG. On the day of the exam, patients were asked to not eat for six hours or drink fluids for one hour prior to the test. Participants arrived at the hospital at 6 PM and a catheter was inserted into the nasal cavity at 7 PM. HRM and esophageal pH measurements were collected via a portable pocket monitor. Post-insertion, patients consumed a test meal comprised of two sandwiches, one Belgian waffle and 500 mL of water at 8 PM before returning home. At 11:30 PM, electrodes of the portable EEG were placed, and the EEG start button and pocket monitor button were activated. Patients were advised to wake up at 6 AM and come back to the hospital for catheter removal.

Nocturnal GER was detected 17 times, with an average of 1.7 hours. TLESR, the primary mechanism for nocturnal GER, was found to be responsible for 88.2% (15/17) of GER episodes. The interval from bedtime to awakening (the measurement time) was 377.6 minutes and sleep time—the interval from falling asleep to awakening—was 325.1 minutes.

Results showed that TLESR during sleep occurred frequently, with 51.9% of nocturnal GER episodes linked to TLESR. Sleep depth during TLESR was 44.2% awake and 34.6% shallow sleep. The majority of TLESR with nocturnal GER episodes (74%) occurred during periods of wakefulness, while only 18.5% happened during shallow sleep stages.

The small sample size coupled with biases in the age and sex of participants limited the study. Despite this, the results in a home setting were comparable to previous studies performed in a hospital setting.

“The present results support the use of more-convenient home measurement in future research,” investigators concluded. “The accuracy of GER data during sleep can be improved by increasing the number of cases, eliminating age and sex biases, and including gastroesophageal reflux disease (GERD) patients in future studies.”