Impact of a Modest Delay in School Start Time in Hong Kong School Adolescents

Abstract Objectives To examine the effect of a modest delay (15 minutes) in school start time (SST) on adolescent sleep patterns, mood, and behaviors. Methods Two secondary schools in Hong Kong with a total of 1173 students (intervention: n = 617; comparison school n = 556) completed both baseline and follow up questionnaires. School start time was delayed by 15 minutes from 7:45am to 8:00am in the intervention school. The comparison school maintained their regular SST at 7:55am. Students’ sleep-wake patterns, daytime sleepiness, mental and behavioral aspects were assessed by validated questionnaires before and after the intervention. Results Students in intervention school significantly delayed their weekday wakeup time ( P < 0.001) and increased their total time in bed ( P < 0.001) when compared to the comparison school. Both groups experienced a delay in their weekday bedtime. The students in the intervention school showed improved mental health [General Health Questionnaire (GHQ) score, P = .015], better prosocial behaviors ( P = .009,), better peer relationship ( P < 0.001, more attentive ( P < 0.001), less emotional problems ( P = .002) and behavioral difficulties ( P < 0.001) as measured by Strengths and Difficulties Questionnaire (SDQ). Conclusions A modest delay (15 minutes) of the school start time can increase adolescent sleep with corresponding improvement in mood and behaviors. Current findings have significant implications for the education policy, suggesting that school administrators and policy makers should systematically consider delaying school start time to promote sleep and health among school-aged adolescents.