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Physiol Behav. 2016 May 1;158:143-9. doi: 10.1016/j.physbeh.2016.03.006. Epub 2016 Mar 9.

Measures of sleep and cardiac functioning during sleep using a multi-sensory commercially-available wristband in adolescents.

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Center for Health Sciences, SRI International, Menlo Park, CA, USA.
Center for Health Sciences, SRI International, Menlo Park, CA, USA; Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa.
Center for Wireless and Population Health Systems, Qualcomm Institute of Calit2, San Diego, USA; Department of Family Medicine and Public Health, University of California, San Diego, USA.
Center for Health Sciences, SRI International, Menlo Park, CA, USA; Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia. Electronic address:


To validate measures of sleep and heart rate (HR) during sleep generated by a commercially-available activity tracker against those derived from polysomnography (PSG) in healthy adolescents. Sleep data were concurrently recorded using FitbitChargeHR™ and PSG, including electrocardiography (ECG), during an overnight laboratory sleep recording in 32 healthy adolescents (15 females; age, mean±SD: 17.3±2.5years). Sleep and HR measures were compared between FitbitChargeHR™ and PSG using paired t-tests and Bland-Altman plots. Epoch-by-epoch analysis showed that FitbitChargeHR™ had high overall accuracy (91%), high sensitivity (97%) in detecting sleep, and poor specificity (42%) in detecting wake on a min-to-min basis. On average, FitbitChargeHR™ significantly but negligibly overestimated total sleep time by 8min and sleep efficiency by 1.8%, and underestimated wake after sleep onset by 5.6min (p<0.05). Within FitbitChargeHR™ epochs of sleep, the average HR was 59.3±7.5bpm, which was significantly but negligibly lower than that calculated from ECG (60.2±7.6bpm, p<0.001), with no change in mean discrepancies throughout the night. FitbitChargeHR™ showed good agreement with PSG and ECG in measuring sleep and HR during sleep, supporting its use in assessing sleep and cardiac function in healthy adolescents. Further validation is needed to assess its reliability over prolonged periods of time in ecological settings and in clinical populations.


Actigraphy; Adolescence; Fitbit; Heart rate; Polysomnography; Wearables

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