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SP1-12 Relationship between sleep duration at 3 years of age and growth during childhood: a multi-level analysis

Introduction Short sleep duration in early life has been thought to be a risk factor for subsequent overweight. This study aimed to examine the relationship between sleep duration at 3 years of age and childhood weight status through a multi-level analysis. Methods The study population comprised children born between 1 April 1991, and 31 March 2003, in Koshu City, Japan, and who participated in a medical check-up at 3 years of age. Short and long sleep durations at 3 years of age were the exposures studied. We compared the trajectory of body mass index (BMI) z-scores from 3 to 9 years of age in exposed and non-exposed participants. Random intercepts and slopes model (SAS Proc Mixed) was used for statistical analysis. Results Of 1794 children who participated in a medical check-up at 3 years of age, 1640 (91.4%) were not over-weight at 3 years and were followed-up until they were 9 or 10 years old. The number of children in each category of sleep duration, that is, ≤9 h, 9–10 h, 10–11 h, and ≥11 h, was 66 (3.7%), 609 (34.0%), 847 (47.2%), and 271 (15.1%), respectively. BMI z-scores increased with increase in age (p=0.03) for boys with a short sleep duration (<9 h). On the other hand, sleep duration was not significantly associated with BMI z-score in girls. Conclusion It was suggested that there is gender difference of the effect of childhood sleep duration on subsequent overweight.