title: Night-to-night arousal variability and interscorer reliability of arousal measurements.
abstract: OBJECTIVE
  Measurement of arousals from sleep is clinically important, however, their definition is not well standardized, and little data exist on reliability. The purpose of this study is to determine factors that affect arousal scoring reliability and night-to-night arousal variability.
  
  
  METHODS
  The night-to-night arousal variability and interscorer reliability was assessed in 20 subjects with and without obstructive sleep apnea undergoing attended polysomnography during two consecutive nights. Five definitions of arousal were studied, assessing duration of electroencephalographic (EEG) frequency changes, increases in electromyographic (EMG) activity and leg movement, association with respiratory events, as well as the American Sleep Disorders Association (ASDA) definition of arousals.
  
  
  METHODS
  NA.
  
  
  METHODS
  NA.
  
  
  METHODS
  NA.
  
  
  RESULTS
  Interscorer reliability varied with the definition of arousal and ranged from an Intraclass correlation (ICC) of 0.19 to 0.92. Arousals that included increases in EMG activity or leg movement had the greatest reliability, especially when associated with respiratory events (ICC 0.76 to 0.92). The ASDA arousal definition had high interscorer reliability (ICC 0.84). Reliability was lowest for arousals consisting of EEG changes lasting <3 seconds (ICC 0.19 to 0.37). The within subjects night-to-night arousal variability was low for all arousal definitions
  
  
  CONCLUSIONS
  In a heterogeneous population, interscorer arousal reliability is enhanced by increases in EMG activity, leg movements, and respiratory events and decreased by short duration EEG arousals. The arousal index night-to-night variability was low for all definitions.
authors.affiliation: Department of Medicine, University of California, San Diego 92103-8378, USA. jloredo@ucsd.edu
authors.forename: J S
authors.initials: JS
authors.lastname: Loredo
authors.forename: J L
authors.initials: JL
authors.lastname: Clausen
authors.forename: S
authors.initials: S
authors.lastname: Ancoli-Israel
authors.forename: J E
authors.initials: JE
authors.lastname: Dimsdale
mesh_terms: D001143:Arousal / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D015588:Observer Variation; D017286:Polysomnography / Q000379:methods; D015203:Reproducibility of Results; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology