Equivalency of sleep estimates: comparison of three research-grade accelerometers

<p>Introduction:</p><p>This study examined equivalency of sleep estimates from Axivity, GENEActiv and ActiGraph accelerometers worn on non-dominant and dominant wrist, and with and without using a sleep log to guide the algorithm.</p><p>Methods:</p><p>Forty-seven young adults wore an Axivity, GENEActiv and ActiGraph accelerometer continuously on both wrists for 4-7 seven days. Sleep time, sleep window, sleep efficiency, sleep onset and wake time were produced using the open-source GGIR package. For each outcome, agreement between accelerometer brands, dominant and non-dominant wrists, and with and without a sleep log, was examined using pairwise 95% equivalence tests (±10% equivalence zone), intra-class correlation coefficients (ICCs) with 95% confidence intervals and limits of agreement (LoA).</p><p>Results:</p><p>All sleep outcomes were within a 10% equivalence zone</p><p>irrespective of brand, wrist, or use of a sleep log. ICCs were poor-to-good for sleep time</p><p> (ICCs>0.66) and sleep window (ICCs>0.56). Most ICCs were good-to-excellent for sleep</p><p>efficiency (ICCs>0.73), sleep onset (ICCs>0.88) and wake time (ICCs>0.87). There were</p><p>low levels of mean bias, however wide 95% LoA for sleep time, sleep window, sleep onset</p><p>and wake time outcomes. Sleep time (up to 25 min) and sleep window (up to 29 min) were</p><p>higher when sleep log was not used. Conclusion: The present findings suggest that sleep</p><p>outcomes from the Axivity, GENEActiv and ActiGraph, when analysed identically, are</p><p>comparable across studies with different accelerometer brands and wear protocols at a group</p><p>level. However, caution is advised when comparing studies that differ on sleep log</p><p>availability.</p>