Delaying school start time by 30 or 60 minutes increased children's sleep duration and reduced daytime sleepiness over two years¶

Claim · All claims
Evidence · 1 study (2 entries) · causal r2 · q2
Currency · newest study 2013 · checked against its sources 2026-10-20 (automated, 2 of 2 entries) · not reviewed by a person

Subclaims¶

q2 i? After delaying school start time 30 and 60 minutes, sleep duration increased by 15.6 and 22.8 minutes respectively, and the intervention significantly improved sleep duration and daytime sleepiness. → Li Shenghui 2013 q2 i? Control schools showed the opposite change over the same period: decreased sleep duration and increased daytime sleepiness. → Li Shenghui 2013 (2)

Evidence¶

Li Shenghui 2013¶

Li Shenghui, Arguelles Lester, Jiang Fan, Chen Wenjuan, Jin Xingming, Yan Chonghuai, Tian Ying, Hong Xiumei, Qian Ceng, Zhang Jun, Wang Xiaobin, Shen Xiaoming. (2013). Sleep, School Performance, and a School-Based Intervention among School-Aged Children: A Sleep Series Study in China. PLoS ONE. https://doi.org/10.1371/journal.pone.0067928

q2 · i? · causal · r2

School-based intervention trial in six Shanghai primary schools using a 3 groups (control, intervention1, intervention2) × 2 times (baseline, 2-year follow-up) design with two schools randomly assigned per group; comparative cross-sectional analysis of pre- (n = 525) and post-intervention (n = 553) surveys of fourth and fifth graders. The article reports "sleep duration correspondingly increased by 15.6 minutes and 22.8 minutes" and a significant improvement in sleep duration and daytime sleepiness; no standardized effect size is printed.

"After delaying school start time 30 minutes and 60 minutes, respectively, sleep duration correspondingly increased by 15.6 minutes and 22.8 minutes, respectively. Moreover, intervention significantly improved the sleep duration and daytime sleepiness."

Li Shenghui 2013 (2)¶

Li Shenghui, Arguelles Lester, Jiang Fan, Chen Wenjuan, Jin Xingming, Yan Chonghuai, Tian Ying, Hong Xiumei, Qian Ceng, Zhang Jun, Wang Xiaobin, Shen Xiaoming. (2013). Sleep, School Performance, and a School-Based Intervention among School-Aged Children: A Sleep Series Study in China. PLoS ONE. https://doi.org/10.1371/journal.pone.0067928

q2 · i? · causal · r2

Same intervention trial, control schools keeping the 7:30am start time; Table 6 shows control sleep duration fell from 9.17±0.73 to 9.01±0.67 (t = −31.48, p<0.001) and frequent daytime sleepiness rose from 23.86% to 36.61%. The article states "an opposite change was observed: a decrease in sleep duration and an up-regulation of daytime sleepiness"; no standardized effect size is printed.

"For the control group, an opposite change was observed: a decrease in sleep duration and an up-regulation of daytime sleepiness."

Discussion¶

Learner Variables¶

• Sleep — outcome: instruction changes it

Related Claims¶

• Daytime sleepiness is highly prevalent among Chinese school-aged children, affecting 64.44% (sometimes 37.50%, frequently 26.94%) — related
• In the intervention trial, short sleep prevalence fell sharply in delayed-start schools (intervention 2: 40.47% to 11.87%) while sufficient-sleep prevalence remained low overall — a narrower finding that bears on this claim
• Frequent daytime sleepiness is associated with impaired academic achievement, attention, and learning motivation in school-aged children — related
• Only 22.34% of Chinese school-aged children get sufficient sleep (≥10 hours), while 37.96% have short sleep duration (<9 hours) — related
• School-based sleep education improves children's sleep duration and quality — related