title: Pupillometric assessment of sleepiness in narcolepsy.
abstract: OBJECTIVE
  Excessive daytime sleepiness is highly prevalent in the general population, is the hallmark of narcolepsy, and is linked to significant morbidity. Clinical assessment of sleepiness remains challenging and the common objective multiple sleep latency test (MSLT) and subjective Epworth sleepiness scale (ESS) methods correlate poorly. We examined the relative utility of pupillary unrest index (PUI) as an objective measure of sleepiness in a group of unmedicated narcoleptics and healthy controls in a prospective, observational pilot study.
  
  
  METHODS
  Narcolepsy (n = 20; untreated for >2 weeks) and control (n = 56) participants were tested under the same experimental conditions; overnight polysomnography was performed on all participants, followed by a daytime testing protocol including: MSLT, PUI, sleepiness visual analog scale (VAS), ESS, and the psychomotor vigilance test (PVT).
  
  
  RESULTS
  The narcolepsy and control groups differed significantly on psychomotor performance and each measure of objective and subjective sleepiness, including PUI. Across the entire sample, PUI correlated significantly with objective (mean sleep latency, SL) and subjective (ESS and VAS) sleepiness, but none of the sleepiness measures correlated with performance (PVT). Among narcoleptics, VAS correlated with PVT measures. Within the control group, mean PUI was the only objective sleepiness measure that correlated with subjective sleepiness. Finally, in an ANCOVA model, SL and ESS were significantly predictive of PUI as measure of sleepiness.
  
  
  CONCLUSIONS
  The role of PUI in quantifying and distinguishing sleepiness of narcolepsy from sleep-satiated healthy controls merits further investigation as it is a portable, brief, and objective test.
authors.affiliation: Center for Narcolepsy, Sleep and Health Research, University of Illinois at Chicago Chicago, IL, USA.
authors.forename: Bharati
authors.initials: B
authors.lastname: Prasad
authors.forename: Young K
authors.initials: YK
authors.lastname: Choi
authors.forename: Terri E
authors.initials: TE
authors.lastname: Weaver
authors.forename: David W
authors.initials: DW
authors.lastname: Carley