title: Moving beyond average values: assessing the night-to-night instability of sleep and arousal in DSM-IV-TR insomnia subtypes.
abstract: OBJECTIVE
  We explored differences between individuals with DSM-IV-TR diagnoses of primary insomnia (PI) and insomnia related to a mental disorder (IMD) by using serial measurements of self-reported sleep variables (sleep onset latency, SOL; wake after sleep onset, WASO; total sleep time, TST; sleep efficiency, SE), and visual analogue scale ratings of 2 forms of bedtime arousal (cognitive and emotional). Furthermore, we sought to examine the relationship between sleep and arousal within each diagnostic subgroup.
  
  
  METHODS
  Between-group and within-group comparisons.
  
  
  METHODS
  Duke and Rush University Medical Centers, USA.
  
  
  METHODS
  One hundred eighty-seven insomnia sufferers (126 women, average age 47.15 years) diagnosed by sleep specialists at 2 sleep centers as PI patients (n=126) and IMD patients (n=61).
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Multilevel models for sleep measures indicated that IMD displayed significantly more instability across nights in their TST (i.e., larger changes) than did PI patients. With respect to pre-sleep arousal, IMD patients exhibited higher mean levels of emotional arousal, as well as more instability on the nightly ratings of this measure. Within the PI group, correlational analyses revealed a moderate relationship between the 2 arousal variables and SOL (r values 0.29 and 0.26), whereas the corresponding correlations were negligible and statistically nonsignificant in the IMD group.
  
  
  CONCLUSIONS
  We found a number of differences on nighttime variables between those diagnosed with primary insomnia and those diagnosed with insomnia related to a mental disorder. These differences imply different perpetuating mechanisms involved in their ongoing sleep difficulties. Additionally, they support the categorical distinctiveness and the concurrent validity of these insomnia subtypes.
authors: University of Murcia, Murcia, Spain.
authors: M Montserrat
authors: MM
authors: Sánchez-Ortuño
authors: Colleen E
authors: CE
authors: Carney
authors: Jack D
authors: JD
authors: Edinger
authors: James K
authors: JK
authors: Wyatt
authors: Andrea
authors: A
authors: Harris
mesh_terms: D001143:Arousal / Q000502:physiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000150:complications / Q000503:physiopathology; D008875:Middle Aged; D017286:Polysomnography; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D012890:Sleep / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000145:classification / Q000209:etiology / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D013997:Time Factors