Short Sleep Duration in the First Years of Life and Obesity/Overweight at Age 4 Years: A Birth Cohort Study

OBJECTIVE: To investigate whether short sleep duration from the first year of life influenced weight at an early age. STUDY DESIGN: During 2004, children born in Pelotas, Brazil, were enrolled in a cohort study. Sleeping habits during the previous 2 weeks were assessed, and the children were weighed and measured at 1-, 2-, and 4-year follow-ups. Overweight and obesity at 4 years were defined according to World Health Organization z-scores for body mass index for age. Short sleep duration was defined as fewer than 10 hours of sleep per night at any follow-up. RESULTS: Out of the 4263 live births, 4231 were recruited. The prevalence of short sleep duration at any follow-up from 1-4 years of age was 10.1%. At 4 years of age, 201 children were obese (5.3%), and 302 (8%) were overweight. Among short sleepers, the prevalence ratio for overweight/obesity after adjusting for maternal and children's characteristics was 1.32 (1.03; 1.70). CONCLUSIONS: Children who slept for fewer than 10 hours per night at any follow-up from 1-4 years of age were more likely to be overweight or obese at 4 years of age, despite their sociodemographic and sleep characteristics.