title: Spontaneous K-complexes in chronic psychophysiological insomnia.
abstract: OBJECTIVE
  Spontaneous K-complexes are electroencephalographic features unique to non-rapid eye movement sleep. It has been suggested that this phasic event is a sleep-protective mechanism. Because insomnia sufferers report poor sleep quantity and quality, the objective of this study was to document the occurrence of spontaneous K-complexes in Stage 2 sleep of individuals with chronic insomnia. Specifically, the number and density of spontaneous K-complexes were studied in psychophysiological insomnia sufferers.
  
  
  METHODS
  This study took place in a sleep and event-related potentials laboratory.
  
  
  METHODS
  Spontaneous K-complexes were scored during Stage 2 sleep on the second and third nights of a four-consecutive-nights protocol of polysomnographic recordings.
  
  
  METHODS
  The sample included 14 participants suffering from psychophysiological insomnia (INS group; mean age=44.1 years) and 14 good sleepers (mean age=38.1 years). Participants underwent sleep and psychological evaluations. INS group participants met the diagnostic criteria for primary psychophysiological insomnia (mean duration of insomnia=9.6 years).
  
  
  METHODS
  Not applicable.
  
  
  RESULTS
  The total number of spontaneous K-complexes and the density according to the total time spent in Stage 2 sleep (spontaneous K-complexes per minute) were compiled. Repeated-measures analyses of variance showed no significant difference in the number and density of spontaneous K-complexes between the INS group (313.98 and 2.66) and the GS group (361.10 and 2.88), respectively.
  
  
  CONCLUSIONS
  These results suggest no deficiency in the sleep-protective mechanism of psychophysiological insomnia sufferers in comparison with good sleepers, as measured by the spontaneous K-complexes' number and density.
authors.affiliation: Ecole de Psychologie, Université Laval, Québec, Canada. celyne.bastien@psy.ulaval.ca
authors.forename: Célyne H
authors.initials: CH
authors.lastname: Bastien
authors.forename: Geneviève
authors.initials: G
authors.lastname: St-Jean
authors.forename: Isabelle
authors.initials: I
authors.lastname: Turcotte
authors.forename: Charles M
authors.initials: CM
authors.lastname: Morin
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lavallée
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
authors.forename: Daniel
authors.initials: D
authors.lastname: Forget
mesh_terms: D000328:Adult; D002908:Chronic Disease; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D012894:Sleep Stages / Q000502:physiology*; D011795:Surveys and Questionnaires