The influence of ethnicity and socioeconomic status on compositional time use and the impact on prevalence of obesity was examined in a 24-hour accelerometry study in 690 children aged 6–10 years. Ethnicity composition was 58% European, 20% Māori, 13% Pasifika and 9% Asian with 34% defined as high deprivation and 66% as low-medium deprivation. All children wore an ActiGraph accelerometer 24 hours a day for 5 days to provide data on sedentary time, sleep and physical activity. European children spent 16.1 minutes longer asleep and 6.6 minutes longer in moderate-to-vigorous physical activity than non-European children. They also spent 10.2 minutes less being sedentary and 12.2 minutes less in low physical activity than non-European children. A 10% longer duration of sleep was more closely associated with differences in BMI than a 10% longer duration of moderate-to-vigorous physical activity. Compositional time use accounted for 9% of the increased risk of obesity in Māori children, 24% in Asian children and 35% in Pasifika children.
