title: Insomniacs' perception of wake instead of sleep.
abstract: OBJECTIVE
  To establish if insomniacs' underestimation of sleep time is due to reduced ability to discriminate between sleeping and waking states.
  
  
  METHODS
  Two night's home polysomnography were compared to sleep diaries. Five laboratory nights employed a series of recorded questions regarding perception of prior sleep-wake state, which were presented during sustained wake and interrupted Stage 2 and REM sleep.
  
  
  METHODS
  Sleep laboratory and participants' homes.
  
  
  METHODS
  Fourteen insomniacs were compared to 8 good sleepers. Mean age for both groups was 58 years.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  A signal detection theory analysis was applied to participants' responses to questions presented overnight in the laboratory concerning judgement of prior sleep-wake state and confidence in their decision. Insomniacs had reduced sleep-wake discriminability in addition to a greater bias toward reporting prior wakefulness in the laboratory compared to good sleepers. These measures correlated significantly with the degree of underestimation of total sleep and overestimation of wake recorded at home.
  
  
  CONCLUSIONS
  Insomniacs' underestimation of total sleep time is the product of prior sleep being misperceived as wake time upon awakening overnight. This misperception may play a role in the perpetuation of insomnia.
authors.affiliation: School of Psychology, Flinders University, South Australia. jdm@senet.com.au
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Mercer
authors.forename: Richard R
authors.initials: RR
authors.lastname: Bootzin
authors.forename: Leon C
authors.initials: LC
authors.lastname: Lack
mesh_terms: D001290:Attitude; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D010465:Perception; D017286:Polysomnography / Q000379:methods; D012720:Severity of Illness Index; D017603:Signal Detection, Psychological; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000453:epidemiology; D012895:Sleep, REM / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*