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.
Copyright © 2014 Elsevier B.V. All rights reserved.