RESUMO
BACKGROUND: Biological rhythm is the daily metabolic cycle of mammals that involves the sleep-wake cycles, hormone release, eating habits and digestion, body temperature, and other important bodily functions that are repeated daily. Thus, greater difficulty in maintaining the circadian rhythms may be involved in the increased risk of obesity. This study assessed the association between biological rhythm disruption and childhood obesity among school children. METHODS: This is a cross-sectional study with 7-8-year-old school children enrolled in a public school in the city of Pelotas-RS. The sample was drawn through multistage sampling. The Biological Rhythms Interview of Assessment in Neuropsychiatry-Kids (BRIAN-Kids) was used to assess the degree of difficulty maintaining the biological rhythm. BMI was calculated as weight/height2 (kg/m2). RESULTS: A total of 596 children and their caregivers participated in this study. The prevalence of obesity was 24% among school children, 28.9% for girls, and 19.4 for boys (p = 0.009). Obese children had greater difficulties in maintaining the biological rhythm compared to nonobese children (p = 0.007). Some of these difficulties included sleep (p = 0.008), overall activities (p = 0.027), social rhythm (p = 0.033), and eating (p = 0.032) pattern. CONCLUSION: Approximately one-quarter of children were obese. This finding was associated with the caregiver characteristics and some difficulties in maintaining the biological rhythm.