Sleep pattern regularity and measures of infant weight and length during the first 6 months.

Purpose: To examine the association between sleep pattern regularity and measures of weight and length in infants.

Design And Methods: This was a prospective observational study conducted in a university-affiliated children's hospital in northern Taiwan. A total of 316 healthy infants recruited during their 6-month well-child checkups had their weight and recumbent length measured, and wore an actigraph on the ankle for a week. Based on average weekday, weekend, and all-week sleep durations, infants were categorized into 3 groups: regular sleep, weekend catch-up sleep, and weekend sleep curtailment. General linear model analyses were performed with the 3 sleep regularity groups as the primary predictor variable of interest and infant anthropometry as the dependent variable.

Results: At risk of overweight, overweight, and obese was present in a total of 62 (19.6%) infants. In both unadjusted and adjusted models, infants in the weekend catch-up sleep group (30.4%) and those in the weekend sleep curtailment group (34.5%) had significantly higher weight-to-length ratios, body mass index, weight-for-age z-scores, and weight velocity of 6-month increments z-scores when compared with infants in the regular sleep group (35.1%, all p < 0.05).

Conclusions: Differences in weekday-weekend sleep exist as early as in the first 6 months of life, and both catch-up sleep and sleep curtailment over the weekend is associated with higher measures of weight and length in infants.

Practice Implications: Sleep assessments in well-child checkups should include not only global assessments of average sleep duration but also address sleep patterns and their regularity.