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How much homework is too much? Identifying thresholds for adolescent sleep and mental health by school stage
Kaixin Liang1, Diyang Qu2, Anni Zhu2
1School of Psychology, Shenzhen University, Shenzhen, China; Department of Psychology, Faculty of Social Sciences, University of Macau, Macao SAR, China.
Objectives:
This study examined the associations between homework duration and mental health, focusing on the mediating role of sleep duration and identifying homework duration thresholds by school stage.
Methods:
We analyzed cross-sectional data from 68,891 Chinese adolescents (52.3 % boys) in Shenzhen in 2021, stratified by school stage (primary/middle/high) and gender. Mental health outcomes included well-being and ill-being (anxiety, depression) indicators. Homework duration was self-reported separately for weekdays and weekends. The mediating role of sleep duration was tested by structural equation modeling. Non-linear associations between homework and outcomes were explored by generalized additive modeling. Critical thresholds were identified by segmented regression.
Results:
Longer homework durations were generally associated with shorter sleep, lower well-being, and higher ill-being. Sleep duration partially mediated the associations between homework and mental health outcomes. Non-linear analysis revealed curvilinear patterns in the associations between homework with sleep and mental health outcomes. While specific thresholds varied by gender and outcomes, approximate optimal thresholds were identified for each school stage: 1.00 h (primary), 1.32 h (middle), and 2.37 h (high) on weekdays; 1.00 h (primary), 1.37 h (middle), and 1.80 h (high) on weekends. Homework durations exceeding these thresholds were generally associated with less sleep and poorer mental health outcomes, while durations below thresholds showed neutral or even positive associations with sleep and mental health outcomes.
Conclusions:
Excessive homework was associated with shorter sleep and poorer mental health. The identification of school-stage-specific thresholds supports educational policies aimed at reducing homework loads and promoting adolescent well-being. However, these findings should be interpreted alongside the study's limitations, including its cross-sectional design and regional sampling, which preclude causal inferences and nationwide generalization.
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