title: Short-term reproducibility and variability of the pupillographic sleepiness test.
abstract: OBJECTIVE
  The pupillographic sleepiness test (PST) measures the amplitude of the fluctuations of pupil size in the dark, which reflects the level of central nervous system activation and thus alertness. The aim of this study was to assess the short-term reproducibility and variability of the results obtained with the PST in normal healthy subjects.
  
  
  METHODS
  The PST was measured at 9.00, 11:00, and 13:00 h on three consecutive days in 13 young adults. Subjective sleepiness was assessed with the Stanford Sleepiness Scale (SSS) and with a Visual Analogue Scale (VAS). The intra-class correlation (ICC), a measure of reproducibility and the intra- and inter-individual variability, was calculated.
  
  
  RESULTS
  ANOVA analysis of the data revealed no significant differences in the PST measurements for testing day. Time of day and subject did however significantly affect the results with an ICC 73.1%. For the SSS and VAS, the ICC was 38.8% and 45.9%, respectively. The intra- and inter-individual variability in PST results did not differ considerably between time and days.
  
  
  CONCLUSIONS
  We conclude that recordings of the PST have a good reproducibility and low intra- and inter-individual variability compared to subjective scales of sleepiness or the Multiple Sleep Latency Test. The PST is thus a viable method to measure daytime sleepiness objectively.
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wilhelm
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Bittner
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Hofmann
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Koerner
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Peters
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Lüdtke
authors.affiliation: Pupil Research Group, Centre for Ophthalmology, University Eye Hospital, Tuebingen, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Wilhelm
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D011680:Pupil / Q000502:physiology*; D015203:Reproducibility of Results; D012890:Sleep / Q000502:physiology*