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The impact of actigraphy parameter choices on sleep estimates in one-month-old infants
Zeina Halbouty1, Lamine Youbi1, Veronique Bach1
1PériTox laboratory (UMR_I 01), UPJV/INERIS, Jules Verne University of Picardy, Amiens, France.
Insights
Choosing actigraphy parameters like time window and activity threshold significantly impacts sleep estimates in infants. A threshold of 15 counts and longer windows provide more consolidated sleep data for one-month-olds.
Area of Science:
- Pediatric sleep research
- Biomedical engineering
- Chronobiology
Background:
- Actigraphy offers a non-invasive method for monitoring infant sleep-wake cycles.
- Accurate sleep detection via actigraphy relies heavily on algorithm parameters, specifically time window and activity threshold.
- This study investigates optimal parameter combinations for infant sleep analysis.
Purpose of the Study:
- To compare various combinations of time window and activity threshold parameters in actigraphy.
- To determine the impact of these parameters on estimating total sleep duration and sleep bout counts in one-month-old infants.
- To identify the most reliable actigraphy settings for infant sleep research.
Main Methods:
- Forty-nine infants (mean age 24.9 days) were monitored for seven days using actigraphy.
- Sleep-wake classification was performed using 3- or 5-minute windows and activity thresholds of 15, 20, or 40 counts.
- Data analysis involved linear mixed-effects models, Poisson regression, and plausibility screening against established pediatric sleep norms.
Main Results:
- Higher activity thresholds led to systematically inflated total sleep duration estimates.
- A 5-minute window significantly reduced sleep bout counts by 50% and increased mean bout duration compared to 3-minute windows.
- The configuration using a 5-minute window and a 15-count threshold (W5-T15) resulted in more consolidated sleep periods.
Conclusions:
- Actigraphy-derived sleep estimates in infants are highly sensitive to the selected activity threshold and time window duration.
- Parameter choices involve trade-offs between detecting brief sleep transitions and reducing fragmentation artifacts.
- Standardized actigraphy parameter settings are crucial for reliable and reproducible sleep research in early infancy.
Introduction:
Actigraphy is a non-invasive method of recording sleep-wake cycles. Accurate detection depends on the choice of algorithm parameters, particularly the time window and activity threshold. This study aims to compare different combination of these parameters for estimating total sleep duration and the number of sleep bouts in one-month-old infants.
Methods:
Forty-nine breastfed infants (aged 24.9 ± 3.6 days) were monitored at home for seven days. Sleep was recorded using an actigraph (MotionWatch8). Raw 60-s epochs were cross-checked with parental sleep report to correct artefactual immobility. Sleep-wake classification used 3- or 5-min windows and thresholds of 15, 20, or 40 counts. For each valid day, total sleep duration, number of sleep bouts, mean sleep bout duration and sleep-period durations were extracted. Analyses included linear mixed-effects models, Poisson regression, and plausibility screening based on pediatric literature values for sleep duration (9.3-20 h). A focused comparison between W3-T15 and W5-T15 configurations assessed sleep bout duration.
Results:
Among the tested configurations, estimated sleep duration ranged from 15.9 to 18.1 h per day, with higher activity thresholds systematically inflating sleep duration. Threshold choice had a strong effect on total sleep duration (p < 0.001), whereas window length had minimal influence. Five-minute windows identified 50% fewer sleep bouts (p < 0.001), and produced substantially longer bout durations (p < 0.001). The W5-T15 configuration increased the proportion of sleep periods lasting 45-60-min sleep periods (7.8% vs. 5.2%, p < 0.001) and reduced the proportion of shorter periods (57.5% vs. 76.9%, p < 0.001). Overall, a threshold of 15 counts yielded the most coherent estimates.
Conclusion:
Actigraphy-derived sleep estimates in one-month-old infants are strongly influenced by the choice of activity threshold and time-window duration. Comparing six configurations revealed clear trade-offs: shorter windows increased sensitivity to brief transitions, whereas longer windows reduced fragmentation artefacts and yielded more consolidated sleep periods. These findings underscore the need for standardized parameter settings in early-infancy actigraphy and provide a reproducible basis for future methodological and validation work.
