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. 2025 Feb 10;48(2):zsae099.
doi: 10.1093/sleep/zsae099.

Jerks are useful: extracting pulse rate from wrist-placed accelerometry jerk during sleep in children

R Glenn Weaver  1 , M V S Chandrashekhar  1 , Bridget Armstrong  1 , James W White Iii  1 , Olivia Finnegan  1 , Aliye B Cepni  1 , Sarah Burkart  1 , Michael Beets  1 , Elizabeth L Adams  1 , Massimiliano de Zambotti  2 , Gregory J Welk  3 , Srihari Nelakuditi  1 , David Brown Iii  1 , Russ Pate  1 , Yuan Wang  1 , Rahul Ghosal  1 , Zifei Zhong  1 , Hongpeng Yang  1
Affiliations

Jerks are useful: extracting pulse rate from wrist-placed accelerometry jerk during sleep in children

R Glenn Weaver et al. Sleep. .

Abstract

Study objectives: Evaluate wrist-placed accelerometry predicted heartrate compared to electrocardiogram (ECG) heartrate in children during sleep.

Methods: Children (n = 82, 61% male, 43.9% black) wore a wrist-placed Apple Watch Series 7 (AWS7) and ActiGraph GT9X during a polysomnogram. Three-Axis accelerometry data was extracted from AWS7 and the GT9X. Accelerometry heartrate estimates were derived from jerk (the rate of acceleration change), computed using the peak magnitude frequency in short time Fourier Transforms of Hilbert transformed jerk computed from acceleration magnitude. Heartrates from ECG traces were estimated from R-R intervals using R-pulse detection. Lin's concordance correlation coefficient (CCC), mean absolute error (MAE), and mean absolute percent error (MAPE) assessed agreement with ECG estimated heart rate. Secondary analyses explored agreement by polysomnography sleep stage and a signal quality metric.

Results: The developed scripts are available on Github. For the GT9X, CCC was poor at -0.11 and MAE and MAPE were high at 16.8 (SD = 14.2) beats/minute and 20.4% (SD = 18.5%). For AWS7, CCC was moderate at 0.61 while MAE and MAPE were lower at 6.4 (SD = 9.9) beats/minute and 7.3% (SD = 10.3%). Accelerometry estimated heartrate for AWS7 was more closely related to ECG heartrate during N2, N3 and REM sleep than lights on, wake, and N1 and when signal quality was high. These patterns were not evident for the GT9X.

Conclusions: Raw accelerometry data extracted from AWS7, but not the GT9X, can be used to estimate heartrate in children while they sleep. Future work is needed to explore the sources (i.e. hardware, software, etc.) of the GT9X's poor performance.

Keywords: actigraphy; ambulatory sleep monitoring; children; heart rate variability; open source; pediatrics – behavior; sleep tracking; validation.

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Figures

Figure 1.
Figure 1.
(A) Vector Magnitude (B) Difference in Vector Magnitude for Apple at a nominal 50 Hz sample rate.
Figure 2.
Figure 2.
(A) Smoother rms difference in acceleration (B) Short time fourier transform i.e. spectrogram illustrating artefacted copy arising from moving average operation. In this example, the copy was far enough removed from the original t and low enough in amplitude that it would not lead to false estimates of heartrate (HR).
Figure 3.
Figure 3.
(A) Phase of Hilbert transformed jerk signal (B) Normalized phase of Hilbert transformed jerk signal and polysomnography electrocardiogram signal with slow motion artifacts removed using a time-domain high-pass filter with a 0.8 seconds window.
Figure 4.
Figure 4.
Bland-Altman plots for accelerometry predicted heart rate beats per minute for actigraph and apple.
Figure 5.
Figure 5.
Bland-Altman plots for accelerometry predicted heart rate beats per minute for actigraph and apple by signal quality. Abbreviations: BPM, beats per minute; ECG, electrocardiogram; HR, heart rate.
Figure 6.
Figure 6.
Bland-Altman plots for accelerometry predicted heart rate beats per minute for actigraph and apple by sleep stage. Abbreviations: BPM, beats per minute; ECG, electrocardiogram; HR, heart rate; REM, rapid eye movement.
Figure 6.
Figure 6.
Bland-Altman plots for accelerometry predicted heart rate beats per minute for actigraph and apple by sleep stage. Abbreviations: BPM, beats per minute; ECG, electrocardiogram; HR, heart rate; REM, rapid eye movement.
Figure 7.
Figure 7.
Percent of HR estimates < 5 BPM, between 5 and 10 BPM, and ≥ 10 BPM different than ECG for actigraph and Apple (A) overall, (B) by sleep stage, and (C) by signal quality. Abbreviations: BPM, beats per minute; ECG, electrocardiogram; HR, heart rate; REM, rapid eye movement.
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References

    1. Goldstone A, Baker FC, Zambotti M. de.. Actigraphy in the digital health revolution: still asleep? Sleep. 2018;41(9). doi: https://doi.org/10.1093/sleep/zsy120 - DOI - PubMed
    1. de Zambotti M, Goldstein C, Cook J, et al.State of the science and recommendations for using wearable technology in sleep and circadian research. Sleep. 2023;47:zsad325. - PubMed
    1. Van De Water AT, Holmes A, Hurley DA.. Objective measurements of sleep for non-laboratory settings as alternatives to polysomnography–a systematic review. J Sleep Res. 2011;20(1pt2):183–200. doi: https://doi.org/10.1111/j.1365-2869.2009.00814.x - DOI - PubMed
    1. de Zambotti M, Goldstone A, Claudatos S, Colrain IM, Baker FC.. A validation study of Fitbit Charge 2™ compared with polysomnography in adults. Chronobiol Int. 2018;35(4):465–476. doi: https://doi.org/10.1080/07420528.2017.1413578 - DOI - PubMed
    1. de Zambotti M, Baker FC, Willoughby AR, et al.Measures of sleep and cardiac functioning during sleep using a multi-sensory commercially-available wristband in adolescents. Physiol Behav. 2016;158:143–149. doi: https://doi.org/10.1016/j.physbeh.2016.03.006 - DOI - PMC - PubMed