title: Construction and validation of the EEG analogues of the Karolinska sleepiness scale based on the Karolinska drowsiness test.
abstract: OBJECTIVE
  Simple methods of sleepiness assessment are greatly needed for both fundamental research and practical applications. The Karolinska drowsiness test (KDT) was applied to construct physiological alertness scales and to validate them against such well-known instrument of subjective sleepiness assessment as the Karolinska sleepiness scale (KSS).
  
  
  METHODS
  Seven-min EEG recordings were obtained with 2-h interval from frontal and occipital derivations during the last 32-50 h of 44-61-h wakefulness of 15 healthy study participants. Occipital alpha-theta power difference and frontal and occipital scores on the 2nd principal component of the EEG spectrum were calculated for each one-min interval of 5-min eyes closed section of the record.
  
  
  RESULTS
  To obtain scores (from 0 to 5) on alertness scales for each of these EEG indexes, all positive one-min values of the index were assigned to 1, and all remaining (negative) values were assigned to 0. Scores on any of the physiological alertness scales were found to be strongly associated with KSS scores.
  
  
  CONCLUSIONS
  Physiological analogues of KSS were offered by utilising the EEG recordings on eyes closed interval of KDT.
  
  
  CONCLUSIONS
  The constructed physiological scales can help in improving validity and user-friendliness of the field and laboratory methods of quantification of drowsy state.
authors.affiliation: Research Institute for Molecular Biology and Biophysics, Siberian Branch of the Russian Academy of Medical Sciences, 2, Timakova Street, Novosibirsk 630117, Russia. putilov@ngs.ru
authors.forename: Arcady A
authors.initials: AA
authors.lastname: Putilov
authors.forename: Olga G
authors.initials: OG
authors.lastname: Donskaya
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D011795:Surveys and Questionnaires; D013997:Time Factors; D014851:Wakefulness; D055815:Young Adult