The sex-specific interaction between food responsiveness and sleep duration explaining body mass index among children.

OBJECTIVE/BACKGROUND: The inverse relationship between sleep duration and body mass index (BMI) has been well established and appears to be stronger among boys than girls. However, less is known about the mechanisms responsible for this sex-specific link. The main aim of the current study was to examine the sex-specific interaction between food responsiveness and sleep duration in explaining BMI among children. This sex-specific moderation will give more insight into a possible underlying food intake mechanism.

PATIENTS/METHODS: In total, 206 caregivers filled out questionnaires on child's sleep duration and food responsiveness (49.5% boys; mean age = 9.5 years; standard deviation = 1.4 years). Child's weight and height were measured, after which age- and sex-specific standardized BMI values (referred to as zBMI here) were calculated. Descriptive statistics and regression analysis were conducted. A potential significant three-way interaction was further examined using simple slopes analysis and slope difference tests.

RESULTS: A significant inverse correlation was found between sleep duration and zBMI for boys, but not for girls. Moreover, a significant and robust three-way interaction between sex, food responsiveness and sleep duration explaining child's zBMI was found. Slope difference tests indicate that the sleep-BMI slopes only significantly differed between high-food-responsive boys and high-food-responsive girls and between high-food-responsive boys and low-food-responsive boys.

CONCLUSIONS: These findings suggest that increased food intake might be a mechanism explaining the inverse sleep-BMI link among boys.