title: Increased production of evoked and spontaneous K-complexes following a night of fragmented sleep.
abstract: OBJECTIVE
  To determine whether K-complex production is better interpreted as being an arousal response or reflective of a sleep protective micro-state.
  
  
  METHODS
  A 3-night study--night 1 as a baseline night, night 2 as a sleep fragmentation night, followed immediately by night 3 as a recovery night. On nights 1 and 3, approximately 400 auditory stimuli were presented during nonREM sleep in the first two sleep cycles, using stimulus parameters previously found to be optimal for K-complex production.
  
  
  METHODS
  The sleep research laboratory at the University of Melbourne.
  
  
  METHODS
  Six young healthy subjects (3 female).
  
  
  METHODS
  One night of sleep fragmentation. Ten-second auditory tones of up to 110 dB were presented throughout the entire night at approximately 1-minute intervals.
  
  
  RESULTS
  Sleep drive was increased on the recovery night, as indicated by increased amounts of slow wave sleep, increased sleep efficiency, and a reduction in stimulus-related alpha activity. The incidence of both evoked and spontaneous K-complexes increased significantly on the recovery night. When K-complex trials were averaged, neither N550 (Fz) amplitude nor latency differed between the 2 nights. When vertex sharp waves were averaged, N350 (Cz) amplitude was increased significantly on the recovery night.
  
  
  CONCLUSIONS
  The increase in K-complex frequency together with the decrease seen in stimulus-related alpha activity supports the view that they reflect a sleep maintenance, rather than an arousal, response.
authors.affiliation: School of Behavioural Science, The University of Melbourne.
authors.forename: Christian L
authors.initials: CL
authors.lastname: Nicholas
authors.forename: John
authors.initials: J
authors.lastname: Trinder
authors.forename: Ian M
authors.initials: IM
authors.lastname: Colrain
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005152:Facial Muscles / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D017286:Polysomnography; D012892:Sleep Deprivation / Q000175:diagnosis / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors