title: Modulation of upper and lower esophageal sphincter tone during sleep.
abstract: OBJECTIVE
  The pressures generated within the upper esophageal sphincter (P(UES)) and lower esophageal sphincter (P(LES)) reflect the integrity of these barriers to gastroesophageal and pharyngoesophageal reflux, respectively. This study sought to describe the effects of sleep, respiration and posture on the function of the UES and the LES and the pressure differentials developed across them.
  
  
  METHODS
  Ten healthy volunteers (7M, 3F: 38+/-10 yr) without a history of sleep-disordered breathing or reflux underwent overnight polysomnography with simultaneous measurement of P(LES) and P(UES) using a purpose-built sleeve device (Dentsleeve). Posture was recorded but not controlled.
  
  
  RESULTS
  Subjects slept for 4.3+/-1.6h. Compared to waking values, both end-inspiratory and end-expiratory Pues were significantly less during slow wave sleep (SWS) (p<0.05). However, P(LES) was unaffected by sleep stage. During wakefulness and all stages of sleep, both P(UES) and P(LES) were greater at end-inspiration than end-expiration (p<0.05). Similar relationships were observed whether subjects were supine or in the lateral decubitus position.
  
  
  CONCLUSIONS
  Sleep decreases the effectiveness of the UES to act as a barrier to pharyngoesophageal reflux, particularly during slow wave sleep (SWS). UES pressure varies with respiration, with minimal values observed during expiration. Hence, barrier function of the UES appears most impaired during SWS, in the expiratory phase of the respiratory cycle. The LES pressure and its barrier pressure also vary with respiration, being least during expiration. However, unlike the UES, the function of the LES was unaffected by sleep.
authors.affiliation: Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia. Peter.Eastwood@health.wa.gov.au
authors.forename: Peter R
authors.initials: PR
authors.lastname: Eastwood
authors.forename: Sawako
authors.initials: S
authors.lastname: Katagiri
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Shepherd
authors.forename: David R
authors.initials: DR
authors.lastname: Hillman
mesh_terms: D000328:Adult; D049630:Esophageal Sphincter, Lower / Q000502:physiology*; D049631:Esophageal Sphincter, Upper / Q000502:physiology*; D045853:Exhalation / Q000502:physiology; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012016:Reference Values; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D014851:Wakefulness / Q000502:physiology