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ActiGraph GT3X+ and Actical Wrist and Hip Worn Accelerometers for Sleep and Wake Indices in Young Children Using an
Claire Smith1, Barbara Galland1, Rachael Taylor2
1Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand.
Insights
This study validated a sleep-scoring algorithm using actigraphy in children, finding hip placement superior for sleep timing and quantity, while wrist placement better for sleep quality metrics.
Area of Science:
- Pediatric sleep research
- Biomedical engineering
- Wearable technology validation
Background:
- Accurate sleep assessment in children is crucial for diagnosing sleep disorders.
- Actigraphy offers a portable alternative to polysomnography (PSG) for sleep monitoring.
- Optimizing actigraphy placement is key to reliable sleep parameter estimation.
Purpose of the Study:
- To validate a count-scaled algorithm for automatic sleep scoring in children.
- To determine optimal accelerometer placement (hip vs. wrist) for sleep assessment.
- To compare algorithm performance against overnight polysomnography (PSG).
Main Methods:
- 28 children (5-8 years) wore two actigraphy devices (ActiGraph GT3X+, Actical) on the hip and wrist.
- 24-hour sleep data were processed using a count-scaled algorithm.
- Actigraphy data were compared with in-home Type 2 PSG for sensitivity, specificity, and sleep outcomes.
Main Results:
- The algorithm demonstrated high sensitivity (89.1%-99.5%) but low specificity (21.1%-45.7%) compared to PSG.
- Sleep offset was accurately measured regardless of device or site.
- Hip placement improved sleep onset accuracy, while wrist placement better estimated sleep quality metrics (WASO, sleep efficiency).
Conclusions:
- The count-scaled algorithm achieves high sensitivity but low specificity for sleep scoring in children.
- No single site placement optimized all sleep variable estimations.
- ActiGraph GT3X+ on the hip is suggested for sleep timing/quantity, wrist for sleep quality, with hip placement performing well for timing but not quality.
Abstract:
Objectives: Our count-scaled algorithm automatically scores sleep across 24 hours to process sleep timing, quantity, and quality. The aim of this study was to validate the algorithm against overnight PSG in children to determine the best site placement for sleep. Methods: 28 children (5-8 years) with no history of sleep disturbance wore two types of accelerometers (ActiGraph GT3X+ and Actical) at two sites (left hip, non-dominant wrist) for 24-h. Data were processed using the count-scaled algorithm. PSG data were collected using an in-home Type 2 device. PSG-actigraphy epoch sensitivity (sleep agreement) and specificity (wake agreement) were determined and sleep outcomes compared for timing (onset and offset), quantity [sleep period time (SPT) and total sleep time (TST)], and quality metrics [sleep efficiency and waking after sleep onset (WASO)]. Results: Overall, sensitivities were high (89.1% to 99.5%) and specificities low (21.1% to 45.7%). Sleep offset was accurately measured by actigraphy, regardless of brand or placement site. By contrast, sleep onset agreed with PSG using hip-positioned but not wrist-positioned devices (difference ActiGraph : PSG 21 min, P < .001; Actical : PSG 14 min, P < .001). The ActiGraph at the wrist accurately detected WASO and sleep efficiency, but under (-34 min, P < .001) and overestimated (5.8%, P < .001) these at the hip. The Actical under- and over-estimated these variables respectively at both sites. Results for TST varied ranging from significant differences to PSG of -26 to 21 min (ActiGraph wrist and hip respectively) and 9 min (ns) to 59 min for Actical (wrist and hip respectively). Conclusion: Overall the count-scaled algorithm produced high sensitivity at the expense of low specificity in comparison with PSG. A best site placement for estimates of all sleep variables could not be determined, but overall the results suggested ActiGraph GT3X+ at the hip may be superior for sleep timing and quantity metrics, whereas the wrist may be superior for sleep quality metrics. Both devices placed at the hip performed well for sleep timing but not for sleep quality. Differences are likely linked to freedom of movement of the wrist vs the trunk (hip) during overnight sleep.
