Objective:

To investigate the association between breastfeeding during the first 6 months of life and sleep duration at 1 year in infants.

Approach:

• Study Design: Analysis of data from the Japan Environment and Children's Study, a nationwide birth cohort study.
• Participants: 82,918 mother-infant pairs with complete data on infant feeding and sleep duration.
• Feeding Categories: Infants categorized as exclusively formula-fed, breastfed for less than 6 months, breastfed for 6 months with formula supplementation, or exclusively breastfed for 6 months.
• Outcome Measurement: Primary outcome was short sleep duration at 1 year, defined as fewer than 11 hours of sleep per day.

Key Findings:

• 12% of exclusively formula-fed infants experienced short sleep duration compared to 10% of exclusively breastfed infants.
• Breastfeeding for less than 6 months was associated with 16% lower odds of short sleep.
• Breastfeeding for 6 months with formula supplementation was associated with 21% lower odds.
• Exclusive breastfeeding for 6 months was associated with 23% lower odds of short sleep.

Interpretation:

The study found an association between breastfeeding during the first 6 months of life and lower odds of short sleep duration at 1 year, but it could not establish causality.

Limitations:

• Feeding practices and sleep duration were based on parental questionnaires, which may introduce recall bias.
• The observational nature of the study limits causal inference.
• The overall effect size was modest, with a maximum absolute difference of about 3 percentage points.
• Residual confounding may remain despite adjustments.

Conclusion:

The study found an association between breastfeeding during the first 6 months of life and a decreased risk of short sleep duration in 1-year-old infants.

Sources:

• European Journal of Clinical Nutrition