Abstract
Background: Thigh-worn accelerometers have established reliability and validity for measurement of free-living physical activity-related behaviors. However, comparisons of methods for measuring sleep and time in bed using the thigh-worn accelerometer are rare. The authors compared the thigh-worn accelerometer algorithm that estimates time in bed with the output of a sleep diary (time in bed and time asleep). Methods: Participants (N = 5,498), from the 1970 British Cohort Study, wore an activPAL device on their thigh continuously for 7 days and completed a sleep diary. Bland–Altman plots and Pearson correlation coefficients were used to examine associations between the algorithm derived and diary time in bed and asleep. Results: The algorithm estimated acceptable levels of agreement with time in bed when compared with diary time in bed (mean bias of -11.4 min; limits of agreement -264.6 to 241.8). The algorithm-derived time in bed overestimated diary sleep time (mean bias of 55.2 min; limits of agreement -204.5 to 314.8 min). Algorithm and sleep diary are reasonably correlated (? =.48, 95% confidence interval [.45,.52] for women and ? =.51, 95% confidence interval [.47,.55] for men) and provide broadly comparable estimates of time in bed but not for sleep time. Conclusions: The algorithm showed acceptable estimates of time in bed compared with diary at the group level. However, about half of the participants were outside of the ±30 min difference of a clinically relevant limit at an individual level.
Original language | English |
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Pages (from-to) | 60-67 |
Number of pages | 8 |
Journal | Journal for the Measurement of Physical Behaviour |
Volume | 4 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Mar 2021 |
Keywords
- activPAL
- sleep
- sleep diary