Delayed school start times to improve sleep duration and mitigate depression in adolescents: a systematic review and...

Delayed school start time (DSST) has been associated with prolonged sleep duration and reduced depressive symptoms. However, the overall magnitude of these effects remains unclear. We therefore conducted a systematic review and meta-analysis to assess the impact of DSST on sleep duration and depressive symptoms among middle and high school students.

We systematically searched Medline, Google Scholar, and Science Direct for studies examining the relationship between DSST and both sleep duration and depression. Four independent reviewers conducted risk-of-bias and quality assessments for each study. For quantitative synthesis, we calculated the standardized mean difference (SMD) using Hedges's g to evaluate changes in sleep duration and depression.

A total of six studies were included in the final meta-analysis. The pooled analysis indicated that DSST was associated with an average increase in sleep duration of 69 min, with an SMD of 0.63, suggesting a moderate effect size. In contrast, analysis of depressive symptoms, based on five studies, produced a pooled SMD of - 0.20, indicating a smaller effect. Both analyses demonstrated high inter-study heterogeneity.

Our findings suggest that DSST is associated with a moderate improvement in sleep duration among middle and high school students, with minimal evidence of publication bias and small-studies effect, while depressive symptoms showed a small reduction. Further research with larger sample sizes and standardized outcome measures is warranted to clarify these associations.