title: The nasal cycle during wakefulness and sleep and its relation to body position.
abstract: OBJECTIVE
  To compare the occurrence, duration, and relative amplitudes of the nasal cycle (NC) during wakefulness and sleep, and to investigate the relationship of the NC to body position.
  
  
  METHODS
  In 20 healthy subjects, the NC was measured by long-term rhinoflowmetry for an average 23.1 hours during wakefulness and sleep. Head and body position were also recorded during the night.
  
  
  RESULTS
  A classic NC was displayed by 50% of subjects during wakefulness and by 75% of the subjects during sleep. Cycle duration during wakefulness was 91.1 minutes (± 65.2; 20-337), increasing significantly during sleep to 178 minutes (± 92.8; 21-498) (P < 0.01). The relative mean flow of the working phase during wakefulness was 67.6% (± 8.0; 58-90), and it was significantly higher during sleep at 82.0% (± 6.8; 63-93) (P < 0.01). On recumbency, there was a significant correlation between body position and resting phase side (r = 0.67; P = 0.024). To a significant extent, positional shifts led to subsequent NC laterality changes (22%; P < 0.01). Conversely, to a significant extent, positional shifts preceded NC laterality changes (57.6%; P < 0.01). Body position changed in a nonsignificant number of cases (30.3%; P = 0.16) due to reversal of the congestion side of the inferior turbinates.
  
  
  CONCLUSIONS
  The results of our study show that the NC during sleep is characterized by longer cycle durations and greater amplitudes than during wakefulness on normal physical activity. Shifts in body position during sleep alter the NC in a specific direction to a significant extent, but the opposite is not the case.
  
  
  METHODS
  4.
authors.affiliation: Department of Otorhinolaryngology, University of Regensburg, Regensburg.
authors.forename: Christian
authors.initials: C
authors.lastname: Rohrmeier
authors.forename: Silke
authors.initials: S
authors.lastname: Schittek
authors.forename: Tobias
authors.initials: T
authors.lastname: Ettl
authors.forename: Michael
authors.initials: M
authors.lastname: Herzog
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Kuehnel
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D025363:Rhinomanometry / Q000379:methods; D012680:Sensitivity and Specificity; D012737:Sex Factors; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
keywords: Nasal cycle; body position; head position; sleep; wakefulness