Abstract Objective To describe and relate individual, family and environmental characteristics, sleep time and 6-sulfatoxymelatonin levels in schoolchildren. Methods This is a cross-sectional and prospective study, carried out in a private educational institution, with children ≥6 years old, after ethical approval. An actigraph and sleep diary were used to assess sleep for 15 days. On the last night, urine was collected to measure 6-sulfatoxymelatonin levels. Descriptive analysis and non-parametric tests were carried out on correlations, considering p<0.05 for significance. Results […]