Agreement of different methods for assessing sleep characteristics: a comparison of two actigraphs, wrist and hip placement, and self-report with polysomnography

Sleep Med. 2014 Sep;15(9):1107-14. doi: 10.1016/j.sleep.2014.04.015. Epub 2014 May 28.


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.

Keywords: Actigraphy; Agreement; GT3X+; Placement (hip, wrist); Polysomnography; SOMNOwatch; Self-report.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actigraphy / instrumentation
  • Actigraphy / methods*
  • Adolescent
  • Adult
  • Aged
  • Female
  • Humans
  • Male
  • Middle Aged
  • Polysomnography / instrumentation
  • Polysomnography / methods*
  • Predictive Value of Tests
  • Self Report*
  • Young Adult