A longitudinal study of sleep-wake patterns during early infancy using proposed scoring guidelines for actigraphy.

Objective/background: We describe developmental and day-to-night sleep patterns across the first six months of life using actigraphy and compare these to mother-reported perceptions of infant sleep.

Patients/methods: This observational, burst design included three, one-week bursts of data collection at six, 15, and 24 weeks of age. Infants wore an actigraphy device (Actiwatch Spectrum) on their right ankle for each one-week period. Data were scored using a SAS-based hierarchical, algorithmic methodology and independently assessed for necessary corrections by two trained scorers in a Visual Basic. Mothers completed the Brief Infant Sleep Questionnaire (BISQ) at each burst. Mixed models tested developmental patterns over time and multilevel models examined day-to-night sleep patterns at each burst.

Results: Daytime nap sleep duration decreased over time (p = 0.02) with marginal significance for nighttime sleep interval duration increasing over time (p = 0.09). Total 24-h sleep duration was time invariant (p > 0.05). These longitudinal patterns were similar when examining mothers' perception of infant sleep. Daily variations demonstrated nighttime sleep interval and maintenance efficiency did not predict next-day nap sleep duration. Yet, at 24 weeks of age, daytime nap sleep was associated with that nights' sleep interval. For every 1-h above infants' average total daytime nap sleep duration, infants slept ∼15 min longer and 1.0% less efficiently that night (p ≤ 0.05). Mothers overestimated daytime nap sleep and total 24-h sleep, when compared to actigraphy (p < 0.01).

Conclusion: Changes to infants' usual daytime sleep duration impacted subsequent sleep bouts and mothers tended to overestimate infants' sleep. These patterns should be explored in relation to parenting practices.