title: Novel method for evaluation of eye movements in patients with narcolepsy.
abstract: Narcolepsy causes abnormalities in the control of wake-sleep, non-rapid-eye-movement (non-REM) sleep and REM sleep, which includes specific eye movements (EMs). In this study, we aim to evaluate EM characteristics in narcolepsy as compared to controls using an automated detector.
  
  
  
  We developed a data-driven method to detect EMs during sleep based on two EOG signals recorded as part of a polysomnography (PSG). The method was optimized using the manually scored hypnograms from 36 control subjects. The detector was applied on a clinical sample with subjects suspected for central hypersomnias. Based on PSG, multiple sleep latency test and cerebrospinal fluid hypocretin-1 measures, they were divided into clinical controls (N = 20), narcolepsy type 2 (NT2, N = 19), and narcolepsy type 1 (NT1, N = 28). We investigated the distribution of EMs across sleep stages and cycles.
  
  
  
  NT1 patients had significantly less EMs during wake, N1, and N2 sleep and more EMs during REM sleep compared to clinical controls, and significantly less EMs during wake and N1 sleep compared to NT2 patients. Furthermore, NT1 patients showed less EMs during NREM sleep in the first sleep cycle and more EMs during NREM sleep in the second sleep cycle compared to clinical controls and NT2 patients.
  
  
  
  NT1 patients show an altered distribution of EMs across sleep stages and cycles compared to NT2 patients and clinical controls, suggesting that EMs are directly or indirectly controlled by the hypocretinergic system. A data-driven EM detector may contribute to the evaluation of narcolepsy and other disorders involving the control of EMs.
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark. Electronic address: julie.anja.engelhard.christensen@regionh.dk.
authors.forename: Julie A E
authors.initials: JAE
authors.lastname: Christensen
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark.
authors.forename: Lykke
authors.initials: L
authors.lastname: Kempfner
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark.
authors.forename: Helle L
authors.initials: HL
authors.lastname: Leonthin
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark.
authors.forename: Mathias
authors.initials: M
authors.lastname: Hvidtfelt
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark.
authors.forename: Miki
authors.initials: M
authors.lastname: Nikolic
authors.affiliation: Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Nordre Ringvej 69, DK-2600, Glostrup, Denmark; Center for Healthy Ageing, University of Copenhagen, Blegdamsvej 3B, DK-2200, Copenhagen N, Denmark.
authors.forename: Birgitte Rahbek
authors.initials: BR
authors.lastname: Kornum
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Nordre Ringvej 57, DK-2600, Glostrup, Denmark; Center for Healthy Ageing, University of Copenhagen, Blegdamsvej 3B, DK-2200, Copenhagen N, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Jennum
mesh_terms: D000293:Adolescent; D000328:Adult; D003718:Denmark / Q000453:epidemiology; D006970:Disorders of Excessive Somnolence / Q000503:physiopathology; D004585:Electrooculography / Q000379:methods; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D000068797:Orexins / Q000134:cerebrospinal fluid* / Q000378:metabolism; D017286:Polysomnography / Q000379:methods; D012890:Sleep / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology; D012893:Sleep Wake Disorders / Q000134:cerebrospinal fluid* / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology*; D055815:Young Adult
chemical_list: C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D000068797:Orexins
keywords: Automatic classification; Electrooculography; Eye movements during sleep; Hypocretin versus non-hypocretin deficiency; Narcolepsy; Polysomnography