title: Hypersomnolence, insomnia and the pathophysiology of upper airway resistance syndrome.
abstract: OBJECTIVE
  In order to test the hypothesis that upper airway resistance syndrome (UARS) is merely an extension of the pathophysiology of obstructive sleep apnea/hypopnea (OSA/H) to less severe pharyngeal collapse during sleep, we compared the severity of hypersomnolence and the prevalence of insomnia in UARS patients to the patterns observed for OSA/H patients. Our goal was to determine whether the severity of hypersomnolence and the prevalence of insomnia observed in UARS patients could have been predicted from the patterns observed among OSA/H patients.
  
  
  METHODS
  We performed a retrospective study of a large consecutive patient series evaluated at an academic sleep disorders center, including 220 OSA/H patients and 137 UARS patients. Patients had no other sleep-related diagnosis and underwent an initial evaluation that included a measure of hypersomnolence [a multiple sleep latency test (MSLT); 95%] or insomnia questionnaire (87%). Patients were characterized by anthropometric data, polysomnographic descriptive measures of sleep, MSLT data and insomnia questionnaire data.
  
  
  RESULTS
  Severity of hypersomnolence decreased over the continuum from severe to mild OSA/H. A model fit to the OSA/H patients to predict severity of hypersomnolence significantly underestimated hypersomnolence in UARS patients, which was comparable in severity to that of patients with mild OSA/H. The frequency of sleep-onset insomnia increased over the continuum from severe to mild OSA/H and increased further in UARS.
  
  
  CONCLUSIONS
  UARS is, in some respects, an extension of OSA/H to less severe pharyngeal collapse, but this does not adequately account for the symptom profile of patients with UARS. A physical model is proposed to account for the excess somnolence in UARS relative to expectations and the increasing frequency of sleep-onset insomnia along the continuum from severe OSA/H to UARS.
authors.affiliation: Division of Pulmonary/Critical Care Medicine, Stony Brook University School of Medicine, Stony Brook, DVA Medical Center, Northport, NY 11768, USA. avram.gold@med.va.gov
authors.forename: Avram R
authors.initials: AR
authors.lastname: Gold
authors.forename: Morris S
authors.initials: MS
authors.lastname: Gold
authors.forename: Keith W
authors.initials: KW
authors.lastname: Harris
authors.forename: Vidal J
authors.initials: VJ
authors.lastname: Espeleta
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Amin
authors.forename: Joan E
authors.initials: JE
authors.lastname: Broderick
mesh_terms: D000328:Adult; D015331:Cohort Studies; D006970:Disorders of Excessive Somnolence / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology*; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology* / Q000503:physiopathology