title: Investigating the night-to-night variability of REM without atonia in Parkinson's disease.
abstract: OBJECTIVE
  Rapid eye movement (REM) sleep behaviour disorder is frequently observed in Parkinson's disease and is characterized electrophysiologically by the absence of atonia during REM sleep. However, the night-to-night variability of REM sleep without atonia is yet to be determined in Parkinson's disease.
  
  
  METHODS
  Using polysomnography, this study measured the variability of REM sleep without atonia across two consecutive nights, using the REM atonia index in 38 patients with Parkinson's disease.
  
  
  RESULTS
  The intraclass correlation coefficient between the REM sleep atonia index across two nights was 0.816 (F = 9.795, p < 0.001) and the difference between the two nights was 4.7% (standard deviation (SD) 8.2).
  
  
  CONCLUSIONS
  The REM atonia index demonstrated low variability across two consecutive nights of PSG. Furthermore, the diagnosis of REM sleep behaviour disorder based on this electrophysiological marker and other clinical variables was in agreement across the two nights.
authors.affiliation: Parkinson's Disease Research Clinic, Brain and Mind Research Institute, The University of Sydney, NSW, Australia. Electronic address: sbolitho@med.usyd.edu.au.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Bolitho
authors.affiliation: Healthy Brain Ageing Clinic, Ageing Brain Centre, Brain and Mind Research Institute, The University of Sydney, NSW, Australia.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Naismith
authors.affiliation: Healthy Brain Ageing Clinic, Ageing Brain Centre, Brain and Mind Research Institute, The University of Sydney, NSW, Australia.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Terpening
authors.affiliation: Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia.
authors.forename: Ron R
authors.initials: RR
authors.lastname: Grunstein
authors.affiliation: Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia; Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, NSW, Australia.
authors.forename: Kerri
authors.initials: K
authors.lastname: Melehan
authors.affiliation: Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia; Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, NSW, Australia.
authors.forename: Brendon J
authors.initials: BJ
authors.lastname: Yee
authors.affiliation: Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia; Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, NSW, Australia; Division of Neurology, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Coeytaux
authors.affiliation: Parkinson's Disease Research Clinic, Brain and Mind Research Institute, The University of Sydney, NSW, Australia.
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
mesh_terms: D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009129:Muscle Tonus / Q000502:physiology; D010300:Parkinson Disease / Q000150:complications* / Q000503:physiopathology*; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D012895:Sleep, REM / Q000502:physiology*
keywords: Parkinson's disease; REM atonia index; REM sleep behaviour disorder; REM without atonia