title: Bradysomnia in Parkinson's disease.
abstract: OBJECTIVE
  Polysomnography studies in Parkinson's disease (PD) patients show altered sleep microstructure with decreased level of arousability, indicating impaired sleep-wake dynamics in PD. The aim of this study was to investigate dynamical aspects of sleep EEG in PD as compared to healthy controls.
  
  
  METHODS
  In this retrospective, controlled study, we applied a previously established mathematical model of sleep EEG analysis (state space model) to PD patients and age- and gender-matched healthy volunteers (N=64). Dynamical aspects of sleep were quantified by measuring the spectral variability of the sleep EEG (by means of state space velocity).
  
  
  RESULTS
  State space analysis revealed preserved global sleep-wake architecture in PD patients, but the velocity of sleep stage transitions was significantly reduced as compared to healthy controls. Correlation analysis revealed a strong association of state space velocity with arousal scores and daily dopamine agonist intake.
  
  
  CONCLUSIONS
  Quantitative analysis of spectral sleep EEG variability (state space velocity) revealed reduced sleep-wake dynamics in PD patients as compared to control subjects.
  
  
  CONCLUSIONS
  We propose state space velocity as an objective and quantitative measure for altered sleep microstructure and as a potential biomarker of sleep alterations in PD, not accessible by conventional sleep analysis.
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland. Electronic address: lukas.imbach@usz.ch.
authors.forename: Lukas L
authors.initials: LL
authors.lastname: Imbach
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Sommerauer
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
authors.forename: Rositsa
authors.initials: R
authors.lastname: Poryazova
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
authors.forename: Esther
authors.initials: E
authors.lastname: Werth
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
authors.forename: Philipp O
authors.initials: PO
authors.lastname: Valko
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Scammell
authors.affiliation: Department of Neurology, University Hospital Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Baumann
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology*; D017286:Polysomnography / Q000379:methods; D012189:Retrospective Studies; D012893:Sleep Wake Disorders / Q000175:diagnosis* / Q000453:epidemiology*
keywords: EEG; Parkinson’s disease; Sleep; Spectral analysis; State space model