title: Nonrestorative sleep as a distinct component of insomnia.
abstract: OBJECTIVE
  Explore characteristics of nonrestorative sleep (NRS) in prospectively defined subgroups of individuals with NRS symptoms, investigate whether NRS can occur independently of difficulties initiating and maintaining sleep (DIS/DMS), and determine its effect on waking function.
  
  
  METHODS
  Cross-sectional and longitudinal population-based study comparing patterns of daytime symptoms, and their persistence, in cohorts of subjects with NRS symptoms grouped according to presence or absence of DIS and DMS.
  
  
  METHODS
  28 sleep centers in the US.
  
  
  METHODS
  Subjects reporting awakening unrestored or unrefreshed at least 3 times weekly over the previous 3 months were classified, based on self-reported sleep problems, to DIS (n = 138), DMS (n = 44), DIS+DMS (n = 125), and NRS-only (no DIS or DMS; n = 192) cohorts. Eighty healthy volunteers formed a control group.
  
  
  METHODS
  None.
  
  
  RESULTS
  Polysomnography confirmed DIS and/or DMS in 56/138 (41%), 18/44 (41%), and 37/125 (30%) subjects in DIS, DMS, and DIS+DMS cohorts, respectively; and absence of DIS or DMS in 115/192 (60%) NRS-only subjects and 52/80 (65%) healthy volunteers. Multiple subject-reported endpoints including the Endicott Work Productivity Scale, Pittsburgh Insomnia Rating Scale, Restorative Sleep Questionnaire, and SF-36, showed that NRS-only subjects had significantly impaired daytime function relative to healthy volunteers, comparable to impairment affecting subjects with DIS and/or DMS. Symptoms persisted over 3 months.
  
  
  CONCLUSIONS
  This study confirms that NRS can occur independently of other components of insomnia. Daytime symptoms were as severe in individuals with NRS-only as those whose NRS symptoms were combined with DIS or DMS.
authors.affiliation: Sleep Center, Henry Ford Hospital, 2799 W. Grand Blvd, Detroit, MI 48202, USA. troth1@hfhs.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Roth
authors.forename: Gary
authors.initials: G
authors.lastname: Zammit
authors.forename: Alan
authors.initials: A
authors.lastname: Lankford
authors.forename: David
authors.initials: D
authors.lastname: Mayleben
authors.forename: Theresa
authors.initials: T
authors.lastname: Stern
authors.forename: Verne
authors.initials: V
authors.lastname: Pitman
authors.forename: David
authors.initials: D
authors.lastname: Clark
authors.forename: John L
authors.initials: JL
authors.lastname: Werth
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods / Q000706:statistics & numerical data; D011446:Prospective Studies; D012720:Severity of Illness Index; D020921:Sleep Arousal Disorders / Q000150:complications / Q000175:diagnosis; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications / Q000175:diagnosis*; D012893:Sleep Wake Disorders / Q000150:complications / Q000175:diagnosis; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult
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