The mediating roles of screen time and sleep duration in the association between extracurricular physical activity and visual acuity in primary school students.
Li J, Wang Y, et al. • Frontiers in public health • 2026
Extracurricular physical activity was positively correlated with visual acuity among primary school students, with statistically detectable indirect associations observed through screen time, sleep duration, and the sequential screen time–sleep duration pathway.
Key Findings
Results
Extracurricular physical activity, screen time, sleep duration, and visual acuity were all significantly correlated with each other among primary school students in Macau.
Sample size was 2,098 primary school students recruited via stratified random cluster sampling in Macau.
Data were collected using questionnaire surveys.
Pearson correlation analysis confirmed significant correlations among all four variables (p < 0.01).
Structural equation modeling was used to assess direct and indirect associations.
Results
The estimated total association between extracurricular physical activity and visual acuity was 0.129.
Total association estimate: 0.129 (95% CI [0.099, 0.162]).
A statistically significant direct association between extracurricular physical activity and visual acuity was identified.
The total indirect association through screen time and sleep duration was 0.058 (95% CI [0.039, 0.082]), accounting for 44.96% of the estimated total association.
Results
Sleep duration partially mediated the association between extracurricular physical activity and visual acuity, accounting for 25.58% of the total association.
Specific indirect association through sleep duration: 0.033 (95% CI [0.020, 0.052]).
Sleep duration accounted for 25.58% of the estimated total association between extracurricular physical activity and visual acuity.
Sleep duration represented the largest single indirect pathway identified in the mediation analysis.
Results
Screen time partially mediated the association between extracurricular physical activity and visual acuity, accounting for 17.05% of the total association.
Specific indirect association through screen time: 0.022 (95% CI [0.010, 0.037]).
Screen time accounted for 17.05% of the estimated total association between extracurricular physical activity and visual acuity.
This represents the second largest single indirect pathway in the mediation model.
Results
A sequential indirect pathway from extracurricular physical activity through screen time and then sleep duration to visual acuity was statistically significant but small.
Sequential indirect association through screen time then sleep duration: 0.003 (95% CI [0.001, 0.006]).
This sequential pathway accounted for 2.33% of the estimated total association.
The finding suggests that screen time may influence visual acuity partly by affecting sleep duration, which in turn affects visual acuity.
Despite being small in magnitude, the confidence interval did not include zero, indicating statistical detectability.
Results
Extracurricular physical activity was positively correlated with visual acuity among primary school students in Macau.
The positive direction of the association indicates that higher levels of extracurricular physical activity were associated with better visual acuity.
Both direct and indirect associations (through screen time and sleep duration) contributed to this overall positive relationship.
The study population consisted of primary school students, a group of particular public health interest for myopia prevention.
What This Means
This research suggests that primary school children in Macau who participate in more extracurricular physical activity tend to have better visual acuity (clearer vision). The study surveyed 2,098 students and used statistical modeling to understand not just whether physical activity and vision are linked, but also how that link works. The researchers found that the relationship between physical activity and visual acuity is only partly direct — a substantial portion (about 45%) appears to work indirectly through two other behaviors: how much time children spend on screens and how long they sleep each night.
Specifically, this research suggests that children who are more physically active outside of school tend to spend less time on screens and sleep longer, and both of these factors are in turn associated with better vision. Sleep duration appeared to be the stronger of the two indirect pathways (accounting for about 26% of the total association), followed by screen time (about 17%). There was also a small but detectable chain effect where physical activity reduced screen time, which then improved sleep, which was then associated with better vision.
This research suggests that promoting physical activity in children may benefit their vision not only directly — perhaps through mechanisms like outdoor light exposure — but also indirectly by discouraging excessive screen use and encouraging adequate sleep. This points to the potential value of addressing screen time and sleep habits alongside physical activity when designing public health programs aimed at protecting children's eyesight, which is especially relevant given rising rates of myopia in school-age children across many parts of Asia.
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Li J, Wang Y, Zhang X, Chen Y, Xi L. (2026). The mediating roles of screen time and sleep duration in the association between extracurricular physical activity and visual acuity in primary school students.. Frontiers in public health. https://doi.org/10.3389/fpubh.2026.1883751