title: Polysomnographic characteristics of daytime sleepiness in obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  The study is intended to explore the nocturnal sleep determinants for excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea syndrome (OSAS).
  
  
  METHODS
  Consecutive patients (n = 182) who had an apnea/hypopnea index (AHI) greater than 5 times per hour were used in this study. EDS (n = 32) was considered present whenever the Epworth sleepiness scale (ESS) score was >10 and the multiple sleep latency test (MSLT) score was <5 min. Absence of EDS (no EDS, n = 48) was determined in patients with an ESS score of <10 and a MSLT score of >10 min.
  
  
  RESULTS
  Compared to no EDS patients, EDS patients exhibited (1) greater AHI and time length of SaO(2) <95%, lower nocturnal SaO(2) during separate rapid eye movement (REM) and NREM periods, and lower total mean and minimum SaO(2) during total recording period; (2) shortened latency to sleep and to REM sleep, and increased total sleep time and sleep efficiency; and (3) increases in the brief arousal index and duration of sleep stage 1. In addition, stepwise logistic regression analysis showed that the arousal index, the time length of SaO(2) <95%, and the latency to REM were independent predictors of EDS.
  
  
  CONCLUSIONS
  The results suggest that EDS in OSAS patients are characterized by the following aspects of nocturnal sleep: (1) severe sleep apnea/hypopnea and hypoxemia, (2) fragmented sleep, (3) low quality of sleep, and (4) high pressure of sleep drive.
authors.affiliation: Sleep Medicine Center, Department of Psychiatry, Department of Otolaryngology, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
authors.forename: Yuanfeng
authors.initials: Y
authors.lastname: Sun
authors.forename: Yuping
authors.initials: Y
authors.lastname: Ning
authors.forename: Lili
authors.initials: L
authors.lastname: Huang
authors.forename: Fei
authors.initials: F
authors.lastname: Lei
authors.forename: Zhe
authors.initials: Z
authors.lastname: Li
authors.forename: Guangyao
authors.initials: G
authors.lastname: Zhou
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Tang
mesh_terms: D000328:Adult; D001143:Arousal; D002681:China; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*; D012895:Sleep, REM; D011795:Surveys and Questionnaires
chemical_list: D010100:Oxygen