NOCTURNAL ESOPHAGEAL MOTOR-ACTIVITY IS DEPENDENT ON SLEEP STAGE

Simultaneous overnight oesophageal pH and manometric and sleep electro encephalographic recordings were performed in eight healthy subjects, aged 20-38 years, to test the hypothesis thal the frequency of primary , swallow related contractions decreases progressively with deeper sle ep stages whereas the frequency of secondary contractions remains cons tant throughout the night. During the nocturnal period (2300 to 0700), periods of oesophageal motor quiescence were interspersed by clusters of contractions detected 5 and 15 cm above the lower oesophageal sphi ncter. Primary contractions decreased in frequency from 1.42/min (medi an) during arousal periods to 0.22/min during stage 1 sleep, 0.05/min during stages 2 to 4 combined, and 0.03/min during rapid eye movement (REM) sleep. Secondary contractions were also most frequent during aro usal periods (0.51/min) and they, too, decreased in frequency during s tage 1 (0.35/min) and stages 2 to 4 combined (0.08/min). During REM sl eep, however, the frequency of secondary contractions increased (0.50/ min) to levels noted during arousal and stage 1 sleep. Compared with p rimary contractions, secondary contractions had a lower amplitude (51. 9 hPa v 76.0 hPa; p=0.0078) and a shorter duration (3.08 v 4.06 s; p=0 .0078). The results of this study suggest that there is no intrinsic o esophageal motor activity in the absence of a stimulatory input from t he central nervous system and that the increased number of secondary c ontractions during REM sleep may be a result of an REM related increas e in autonomic nervous system activity although a temporary decrease o f efferent inhibitory influences cannot be ruled out. Nocturnal contra ction clusters comprise both primary contractions during arousals and stage 1 sleep and secondary contractions during REM sleep.