Comparison of sleep estimation using wrist actigraphy and waist actigraphy in healthy young adults

The aim of this study was to compare the simultaneous analysis of sleep using wrist actigraphy and waist actigraphy in healthy young subjects. We studied 102 healthy university students (55 men, 47 women), aged 18–40 years. Participants were instructed to continue normal life activities and sleep—wake rhythms for 7 consecutive nights without extraordinary events. Wrist actigraphy was measured using the Octagonal Basic Motionlogger Actigraph (actigraph), and waist actigraphy was recorded using the Lifecorder PLUS. Data for 633 nights from 95 participants were analyzed to determine sleep onset latency, wake episodes, wake after sleep onset (WASO), time in bed, total sleep time (TST) and sleep efficiency (SE). No significant differences were found between the two methods for the measurement of sleep onset latency and time in bed. Significant differences in measurements were identified for wake episodes (F1,1265 = 126.39, P < 0.001), WASO (F1,1265 = 1139.39, P < 0.001), TST (F1,1265 = 275.21, P < 0.001), and SE (F1,1265 = 1258.31, P < 0.001). The Lifecorder was found to considerably overestimate WASO relativetothe actigraph, leadingto a corresponding underestimation of TST and SE relative to the actigraph. Our results in this population of young healthy adults identify important similarities and differences between the two methods for quantifying sleep.