(P27-072-25) Infant Night Sleep Trajectories Differ by Feeding Mode

Objectives: Infant feeding and sleep behaviors are highly personal and often driven by cultural norms. Common beliefs among mothers are that formula feeding can improve infant night sleep duration (INS) and that bed-sharing may aid in prolonging breastfeeding (BF). Despite these behaviors, little is known about how these two practices impact INS over time. Understanding these relationships is crucial for formulating recommendations to support BF and address sleep concerns. This analysis examined if feeding mode and bed-sharing were associated with INS.

Methods: Infants in the Phoenix Metropolitan Area (n=193) were followed at 3, 8, 13, 26, 39, and 52 weeks. Sleep data were collected via the Brief Infant Sleep Questionnaire and infant feeding practices were characterized using the CDC Infant Feeding Practices II Study Questionnaire. The analysis consisted of a multilevel growth model using INS as the outcome and bed-sharing and feeding mode (exclusive BF, mixed feeding, and exclusive formula feeding) as time-variant predictors. Maternal education was a covariate to account for differences in behavior and a higher dropout rate among mothers with lower education levels.

Results: The model showed a curvilinear trajectory for INS, starting at an average of 7.09 h (95% CI: 5.01, 9.16) and increasing, on average, by 0.45 h/month (95% CI: 0.26, 0.64). The increase in INS decelerated over time by 0.02 h/month² (p < 0.001). Despite 57.9% of bedsharers being exclusively breastfed, the model found no significant association of bedsharing with INS. Exclusive BF was associated with longer INS compared to exclusively formula-fed infants (B = 1.32 h, p < 0.001), but its effect weakened as the infant aged (B = -0.11 h/month, p < 0.001). Mixed feeding had a similar positive effect on INS (B = 0.60 h, p = 0.02) but had no interaction with time.

Conclusions: These findings suggest that breastfed infants across infancy have significantly higher INS when compared to exclusively formula-fed infants. While the majority of bed-sharers were breastfed, bedsharing did not have an impact on INS. Future studies should examine these associations further by investigating the influence of feeding mode shifts on INS and at what time these shifts are most impactful across infancy.

Funding Sources: This work was supported by the National Institutes of Health through awards 1R01HL147931 and T32DK137525.