Figure 3

Mean physical activity across the hours of the day, comparing children either side of the changing of the clocks. CI = confidence interval, cpm = counts per minute. Analysis based on 1830 schooldays from 439 children from 11 studies in 9 countries. Analyses restricted to children with at least one valid schoolday measurement day both before and after the clocks changed; to increase power, data from across the spring and autumn clock changes are pooled. Hours are grouped into two-hour time periods to increase power and are rounded down, e.g. ‘7-8’ covers ‘07:00–08:59’. Adjustment was not essential as each child serves as his or her own control, but the results were similar in adjusted analyses.