title: The spontaneous eye-blink as sleepiness indicator in patients with obstructive sleep apnoea syndrome-a pilot study.
abstract: OBJECTIVE
  To evaluate the spontaneous eye-blink as drowsiness/sleepiness indicator in patients with obstructive sleep apnoea (OSA) syndrome.
  
  
  METHODS
  Using a contact-free sensor for the recording of spontaneous eye-blinks, we investigated the diagnostic value of spontaneous blink parameters in 21 OSA patients. Before the study, all patients underwent a night of polysomnography. Eye-blinks were studied the following morning before therapy, and again after the first therapy night with nasal continuous positive airway pressure (nCPAP), to investigate whether blink parameters reflected changes of alertness pre- and post-nCPAP treatment. General daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). The current subjective state was determined by means of standardised questionnaires directly before recording the eye-blinks. Studies were conducted in two sleep laboratories in hospitals.
  
  
  RESULTS
  In OSA patients with excessive daytime sleepiness (EDS; ESS >10, respiratory disturbance index [RDI]=42.4) several parameters proved informative for sleepiness diagnostics. Reduction of blink duration and reopening time as well as increase in blink frequency were significant; furthermore, proportion of long-closure duration blinks indicated reduced sleepiness. OSA patients without EDS (ESS < or =10, RDI=33.5) did not reveal systematic changes of the blink parameters registered after one night of nCPAP intervention.
  
  
  CONCLUSIONS
  Specific parameters of the spontaneous eye-blink may be applied as a sleepiness index for diagnostics in OSA patients. Further studies are needed to prove the diagnostic value of blink parameters and their advantages in comparison to subjective measures commonly used in clinical studies.
authors.affiliation: ENT-Clinic Charité-University Medicine Berlin, Joint Facility of Free University and Humboldt-University, Campus Charité Mitte, Schumannstrasse 20/21, 10117 Berlin, Germany.
authors.forename: Philipp P
authors.initials: PP
authors.lastname: Caffier
authors.forename: Udo
authors.initials: U
authors.lastname: Erdmann
authors.forename: Peter
authors.initials: P
authors.lastname: Ullsperger
mesh_terms: D000328:Adult; D000368:Aged; D001767:Blinking; D002940:Circadian Rhythm; D045422:Continuous Positive Airway Pressure / Q000379:methods; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000175:diagnosis / Q000628:therapy