title: Agreement of different methods for assessing sleep characteristics: a comparison of two actigraphs, wrist and hip placement, and self-report with polysomnography.
abstract: OBJECTIVE
  To assess the agreement of sleep parameters measured by two actigraphs (SOMNOwatch plus, ActiGraph GT3X+) at two different placements (wrist, hip) and of self-reported sleep with polysomnography (PSG).
  
  
  METHODS
  We estimated agreement with PSG for total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), number of awakenings after sleep onset (NASO), and sleep efficiency (SE%) for 100 participants of the general population, aged 18-75 years by judging mean differences to PSG and intervals of agreement using Bland-Altman plots.
  
  
  RESULTS
  Mean difference to PSG for TST was 8.3 min (95% confidence intervals [CI] -7.4; 24.1) for SOMNOwatch plus (wrist), 39.8 min (95% CI 24.3; 55.3) for self-report, -79.0 min (95% CI -89.0; -68.9) for SOMNOwatch plus (hip), and -81.1 min (95% CI -91.9; -70.4) for GT3X+ (hip), respectively. The width of intervals of agreement differed with the placement of the devices. Mean differences to PSG were higher for hip-based measurements compared with wrist placement for most parameters.
  
  
  CONCLUSIONS
  Agreement of sleep parameters assessed by actigraphy with PSG differs with the placement of the device and is limited for hip-based measurements. Agreement of self-report with PSG is comparable to that of actigraphy for some parameters.
authors.affiliation: Institute of Clinical Epidemiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany. Electronic address: melanie.zinkhan@uk-halle.de.
authors.forename: Melanie
authors.initials: M
authors.lastname: Zinkhan
authors.affiliation: Institute of Epidemiology and Social Medicine, Westphalian Wilhelms-University Münster, Münster, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Berger
authors.affiliation: Leibniz Institute for Prevention Research and Epidemiology - BIPS GmbH, Bremen, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Hense
authors.affiliation: Institute of Epidemiology and Social Medicine, Westphalian Wilhelms-University Münster, Münster, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Nagel
authors.affiliation: Department of Internal Medicine B, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Obst
authors.affiliation: Department of Internal Medicine B, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Koch
authors.affiliation: Interdisciplinary Center of Sleep Medicine, Charité University Hospital, Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Penzel
authors.affiliation: Interdisciplinary Center of Sleep Medicine, Charité University Hospital, Berlin, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Fietze
authors.affiliation: Leibniz Institute for Prevention Research and Epidemiology - BIPS GmbH, Bremen, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ahrens
authors.affiliation: Department of Neurology - Sleep Medicine and Neuromuscular Disease, Westphalian Wilhelms-University Münster, Münster, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Young
authors.affiliation: Department of Clinical Neurophysiology, Klinikum Bremen-Ost, Bremen, Germany; Department of Neurology, Klinik Maria Frieden, Telgte, Germany.
authors.forename: Svenja
authors.initials: S
authors.lastname: Happe
authors.affiliation: Institute of Physics, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kantelhardt
authors.affiliation: Institute of Medical Epidemiology, Biostatistics and Informatics, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kluttig
authors.affiliation: Institute of Clinical Epidemiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Schmidt-Pokrzywniak
authors.affiliation: Department of Psychiatry and Psychotherapy, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Pillmann
authors.affiliation: Institute of Clinical Epidemiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany; School of Public Health, Department of Epidemiology, Boston University, Boston, MA, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Stang
mesh_terms: D056044:Actigraphy / Q000295:instrumentation / Q000379:methods*; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000295:instrumentation / Q000379:methods*; D011237:Predictive Value of Tests; D057566:Self Report; D055815:Young Adult
keywords: Actigraphy; Agreement; GT3X+; Placement (hip, wrist); Polysomnography; SOMNOwatch; Self-report