Results
sleep disturbance, −0.21
The final sample comprised 100 children (52 girls [52%]; mean [SD] age, 10.3 [1.4] years). During the sleep restriction week, children went to sleep 64 (95% CI, 58-70) minutes later, and sleep offset (wake time) was 18 (95% CI, 13-24) minutes later, meaning that children received 39 (95% CI, 32-46) minutes less of total sleep per night compared with the sleep extension week in which the total sleep time was 71 (95% CI, 64-78) minutes less in the per-protocol sample analysis. Both parents and children reported significantly less sleep disturbance at night but greater sleep impairment during the day with sleep restriction. Significant standardized reductions in physical well-being (standardized mean difference [SMD], −0.28; 95% CI, −0.49 to −0.08), coping in a school environment (SMD, −0.26; 95% CI, −0.42 to −0.09), and total HRQOL score (SMD, −0.21; 95% CI, −0.34 to −0.08) were reported by children during sleep restriction, with an additional reduction in social and peer support (SMD, −0.24; 95% CI, −0.47 to −0.01) in the per-protocol sample analysis.