Sleep duration among breastfed, goat milk-based or cow's milk-based infant formula-fed infants: Post hoc analyses from a double-blind RCT

Objectives: To determine total, night- and daytime sleep duration and waking frequency among infants exclusively fed goat milk-based infant formula (GMF) or cow's milk-based infant formula (CMF) enroled in a randomised controlled trial and compare these to a human milk (HM) fed reference group.

Methods: Post hoc analysis from a double-blind randomised controlled trial in 304 healthy term infants was performed. Formula-fed infants were randomly assigned to receive exclusively GMF or CMF for a period of 112 days and compared to a reference group fed HM. Sleep was assessed using a 3-day 24-h diary before the five visits throughout the trial. The association between feeding type and sleep was studied longitudinally and cross-sectionally at the five visits. All models were adjusted for infant sex and study site of enrolment. For associations between formula-fed infants and the non-randomised HM group, additional adjustments were made.

Results: Total sleep duration slowly and similarly decreased over the course of study duration for all groups, with a decrease of about an hour between the first and last measurement. Longitudinally, daytime sleep duration was significantly longer for GMF (mean 8.6 h, standard error [SE] 0.17) and HM (8.8, 0.18) fed infants as compared to CMF (8.1, 0.17; p < 0.05). Cross-sectional analyses show that infants fed GMF or HM had higher total sleep duration than infants fed CMF at all visits, with significant differences between the groups at Visits 3 and 4.

Conclusions: In infants fed GMF a significantly longer daytime sleep duration and a non-significant trend towards a longer total sleep duration were found when compared to infants fed CMF. These findings suggest that nutrition plays a role in sleep duration.