Breastfeeding is associated with longer infant night sleep duration, whereas bedsharing showed no association despite its correlation with breastfeeding.
Key Findings
Results
Infant night sleep duration followed a curvilinear trajectory during the first postnatal year, starting at approximately 7.92 hours and increasing over time with deceleration.
Starting night sleep duration was 7.92 h (95% CI: 5.78, 10.06)
Night sleep increased by 0.40 h/month (95% CI: 0.21, 0.60)
The rate of increase decelerated over time at 0.02 h/month², p < 0.001
Infants were followed at 3, 8, 13, 26, 39, and 52 weeks post-birth
Sample consisted of 193 infants in the Phoenix Metropolitan Area
Results
Each increase in levels of breast milk consumption was associated with longer infant night sleep duration.
Each ordinal increase in breast milk consumption was associated with an increase of 0.87 h in infant night sleep duration (p < 0.001)
Feeding mode was measured on an ordinal scale: exclusive formula, mixed, and exclusive breastfeeding
The association between breastfeeding and longer night sleep weakened as the infant aged (B = -0.07 h/month, p < 0.001)
A multilevel growth model was used with feeding mode as a time-variant predictor
Results
The positive association between breastfeeding and infant night sleep duration weakened as the infant aged.
The interaction term for feeding mode by infant age was B = -0.07 h/month, p < 0.001
This indicates that while breastfeeding was associated with longer night sleep early in infancy, this effect diminished over the first year
Feeding mode was treated as a time-variant predictor, allowing for changes in feeding practices over the study period
Results
Bedsharing was not significantly associated with infant night sleep duration despite being correlated with breastfeeding.
59.7% of bedsharing infants were exclusively breastfed
Bedsharing was included as a time-variant predictor in the multilevel growth model
The association between bedsharing and infant night sleep duration was not statistically significant
Bedsharing and breastfeeding are correlated practices, yet they had independent relationships with night sleep
Results
Night-weaning was not significantly associated with infant night sleep duration.
Night-weaning was included as a time-variant predictor in the multilevel growth model
No statistically significant association was found between night-weaning and infant night sleep duration
Night-weaning was assessed via sleep and feeding questionnaires at each of the six study visits
Methods
The study used a multilevel growth model to estimate infant night sleep duration trajectories across the first postnatal year.
193 infants in the Phoenix Metropolitan Area were followed up at 6 time points: 3, 8, 13, 26, 39, and 52 weeks post-birth
Feeding mode (ordinal: exclusive formula, mixed, exclusive breastfeeding), night-weaning, and bedsharing were included as time-variant predictors
Maternal education and household income were included as covariates to account for differences in study attrition
Sleep and feeding questionnaires were completed at each visit
Background
Short sleep and formula feeding during infancy are associated with increased risk of childhood obesity, providing the rationale for examining their relationship.
The background identifies short sleep and formula feeding as risk factors for childhood obesity
Feeding practices and sleep arrangements were noted to vary dynamically during infancy
The authors state that understanding these relationships is 'crucial for formulating recommendations to support breastfeeding and address sleep concerns'
What This Means
This research suggests that how infants are fed — specifically whether they receive breast milk — is meaningfully linked to how long they sleep at night during their first year of life. In a study of 193 infants followed over the first year, researchers found that infants who received more breast milk (compared to formula) slept longer at night. For each step up the scale from exclusive formula to mixed feeding to exclusive breastfeeding, infants slept about 52 additional minutes per night on average. However, this advantage appeared to shrink as babies got older, suggesting the feeding-sleep relationship is strongest in early infancy.
The study also examined two other common infant sleep-related practices: bedsharing (sleeping in the same bed as a parent) and night-weaning (stopping nighttime feedings). Despite nearly 60% of bedsharing infants being exclusively breastfed, bedsharing itself was not associated with longer or shorter night sleep. Similarly, night-weaning was not significantly linked to changes in night sleep duration. This suggests that breastfeeding, rather than the sleeping arrangement or the timing of dropping nighttime feeds, may be the key factor related to infant night sleep.
This research matters because short sleep in infancy has been linked to higher risk of childhood obesity and other health concerns. The findings add to the known benefits of breastfeeding by suggesting it may also support longer nighttime sleep in infants. For families and healthcare providers thinking about infant sleep, this research highlights breastfeeding as a practice that may naturally support sleep development, though it also underscores that sleep patterns change over the first year regardless of feeding method.
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Olson M, Liu L, Reifsnider E, Coonrod D, Panchanathan S, Petrov M, et al.. (2026). Feeding Mode Is Associated with Infant Night Sleep Trajectories During the First Postnatal Year.. Nutrients. https://doi.org/10.3390/nu18111650