Familial risk moderates the association between sleep and zBMI in children.

Objective: A cumulative risk approach was used to examine the moderating effect of familial risk factors on relations between actigraphy-based sleep quantity (minutes) and quality (efficiency) and sex- and age-standardized body mass index (zBMI).

Methods: The sample included 124 boys and 104 girls with a mean age of 10.41 years (SD = 0.67). Children wore actigraphs for 1 week, and their height and weight were assessed in the lab.

Results: After controlling for potential confounds, multiple regression analyses indicated that sleep minutes predicted children's zBMI and that both sleep minutes and efficiency interacted with family risk in the prediction of zBMI. The association between poor sleep and zBMI was especially evident for children exposed to higher levels of family risk.

Conclusions: Findings suggest that not all children who exhibit poor sleep are at equal risk for higher zBMI and that familial and contextual conditions need to be considered in this link.