Association Between Sleep Duration and Body Mass Index Among US Low-Income Preschoolers.

OBJECTIVE

To verify whether sleep duration was related to body mass index z scores (zBMI) and whether bedtimes or ethnicity was a moderator of the sleep duration-zBMI association among preschoolers from low-income families.

METHODS

Two hundred twenty-eight African American and Hispanic parents and their preschoolers were recruited from Head Start Centers. Parents reported their preschoolers' sleep duration and bedtimes (using the Children's Sleep Habits Questionnaire) and their television watching. Food intake was measured using multiple days of digital photography to estimate energy intake at dinner. The Parenting Stress Index and the Center for Epidemiologic Studies Depression Scale were used to measure stress and depression. Parents' and preschoolers' height and weight were measured by trained staff.

RESULTS

Longer sleep duration was significantly associated with lower zBMI when controlling for demographics, bedtimes, energy intake at dinner, and television watching, but not when also controlling for parents' demographics, BMI, stress, and depression. Preschoolers' sleep duration-zBMI association was not moderated by bedtimes or ethnicity.

CONCLUSIONS

Longer sleep duration was associated with lower zBMI among low-income preschoolers when controlling for preschoolers' characteristics, but this was no longer the case when also controlling for parents' characteristics. Additional studies are needed on the moderators of the sleep duration-zBMI association among low-income preschoolers.