Peer-reviewed article
L5 onset as a proxy for circadian phase in infants.
Rebeca Buest de Mesquita Silva, Adrielle Holler Pykocz, Hanna Victoria Leal, Mario Andre Leocadio-Miguel, Fernando Mazzilli Louzada et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This is a technical study about measuring circadian rhythms in 6-month-old infants using actigraphy data. The researchers examined whether L5 onset (the start of the least active 5-hour period) could serve as a practical alternative to the mid-sleep point for assessing circadian phase. They analyzed 502 nights of sleep data from 81 infants and found a positive correlation between the two measures, suggesting L5 onset could be a useful proxy when standard sleep-scoring algorithms are not validated for infants.
Key points
- Study analyzed 502 nights of actigraphy data from 81 six-month-old infants
- Positive correlation found between mid-sleep point and L5 onset (r = 0.22, p < 0.001)
- Linear mixed-effects models showed significant associations both between infants (β = 0.63) and within infants (β = 0.10)
- L5 onset offers a practical alternative when sleep algorithms lack infant-specific validation
Limitations
This is a methodological study focused on measurement techniques rather than child well-being outcomes. It does not evaluate the impact of circadian assessment on infant health, development, or any intervention to improve child welfare.
Abstract
Chronotype is commonly assessed using the mid-sleep point as an indicator of circadian phase. In infants, however, this assessment typically relies on actigraphy, and most available sleep-scoring algorithms have been developed and validated for adolescents and adults, limiting their applicability in early childhood. The aim of this study was to examine the relationship between the mid-sleep point and L5 onset, a nonparametric measure derived from rest-activity rhythms that reflects the start of the least active 5-h period. A total of 502 nights from 81 six-month-old infants were analyzed. Sleep onset and offset were determined by visual inspection of actograms, and the mid-sleep point was subsequently calculated. A positive correlation was observed between mid-sleep point and L5 onset (r = 0.22, p < 0.001). Linear mixed-effects models indicated significant associations both between infants (β = 0.63, p < 0.001) and within infants (β = 0.10, p < 0.001). These findings suggest that L5 onset may serve as a practical proxy for circadian phase in 6-month-old infants, offering an alternative to sleep parameters derived from algorithms not specifically validated for this age group.