Bedtime routines and objectively assessed sleep in infants

To examine the association of the timing and consistency of parent bedtime routines with infant night-time sleep duration and variability.

This was a prospective observational study conducted between November 2012 and November 2016.

Three hundred and twenty healthy 6-month-old infants were recruited from the well-child clinics of a university-affiliated hospital in northern Taiwan. Participating families provided sociodemographic, health and bedtime routine information. Infants wore an actigraph on the ankle for a week. General linear model analysis was performed with the frequency and timing of bedtime routines treated as the primary predictor variables of interest.

One hundred and ninety-seven (61.6%) parents started the bedtime routine for infants after 9 PM, with 162 (50.6%) not having the exact same bedtime routine every night. In both crude and adjusted analyses, starting a bedtime routine after 9 PM was associated with shorter infant night-time sleep duration (b = -23.55, p < 0.01). Infants with a bedtime routine of <3-4 nights per week were associated with more variable night-time sleep duration than a bedtime routine of 5-6 nights per week (b = -7.81, p < 0.05) or every night (b = -8.47, p < 0.05).

A bedtime routine of at least 5 nights a week and initiated no later than 9 PM was associated with longer and less variable night-time sleep in infancy. Findings suggest that a consistent bedtime routine implemented in accordance with age-appropriate bedtimes should be addressed as part of anticipatory guidance in the well-child clinics. Future studies should include infant sleep variability as an outcome in addition to the conventional mean-level sleep variable analyses to more thoroughly characterize bedtime routine effects.