title: Clinical Considerations of Obstructive Sleep Apnea with Little REM Sleep.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is more severe during rapid eye movement (REM) sleep than during non-REM sleep. We aimed to determine the features of patients with OSA who experience little REM sleep.
  
  
  METHODS
  Patients with a chief complaint of sleep-disordered breathing were enrolled. All subjects underwent overnight polysomnography (PSG) and completed questionnaires on sleep quality. Patients were divided into the following three groups according to the proportion of REM sleep detected in overnight PSG: little REM sleep [REM sleep <20% of total sleep time (TST)], normal REM sleep (20-25% of TST), and excessive REM sleep (>25% of TST). Multiple logistic regression analyses were applied to the data. The success rate of continuous positive airway pressure (CPAP) titration was estimated in these groups.
  
  
  RESULTS
  The age and body mass index of the patients were 47.9±15.9 years (mean±SD) and 25.2±4.1 kg/m², respectively. The 902 patients comprised 684 (76%) men and 218 (24%) women. The apnea-hypopnea index (AHI) in the little-REM-sleep group was 22.1±24.4 events/hour, which was significantly higher than those in the other two groups (p<0.05). Multiple logistic regression showed that a higher AHI (p<0.001; odds ratio, 1.512; 95% confidence interval, 1.020-1.812) was independently predictive of little REM sleep. The titration success rate was lower in the little-REM-sleep group than in the normal-REM-sleep group (p=0.038).
  
  
  CONCLUSIONS
  The AHI is higher and the success rate of CPAP titration is lower in OSA patients with little REM sleep than those with normal REM sleep.
authors.affiliation: Department of Neurology, Seoul National University Boramae Hospital, Seoul, Korea.
authors.forename: Dae Lim
authors.initials: DL
authors.lastname: Koo
authors.affiliation: Department of Neurology, Seoul National University Boramae Hospital, Seoul, Korea. hwnam85@gmail.com.
authors.forename: Hyunwoo
authors.initials: H
authors.lastname: Nam
keywords: REM sleep; apnea-hypopnea index; continuous positive airway pressure; obstructive sleep apnea; polysomnography