School greenspace may buffer against the detrimental effects of screen time for disadvantaged studentsConcerning rates of mental health problems among adolescents have received much attention and global estimates suggest that one in seven adolescents are facing a mental health issue. Adolescents are spending excessive amounts of time engaged in screen-based activities, which prior research has demonstrated to be detrimental to young people’s mental health. Conversely, existing research indicates that exposure to natural or green environments is associated with positive mental health and well-being. To clarify how screen time, exposure to nature, and mental health are connected, this nationwide study in China aimed to examine the relationships between greenery around schools, recreational screen time, and depressive symptoms in adolescents.
Researchers collected data from 22,868 adolescents in junior and senior high schools located in eight cities throughout different regions in China. At least 600 students per school and 2,400 students per region completed questionnaires to assess depressive symptoms as measured by the Patient Health Questionnaire Depression Scale (PHQ-9). Responses were scored and PHQ-9 scores greater than nine were considered a positive screen for depression. The level of greenness around participants’ schools was assessed using the Normalized Vegetation Index (NDVI). NDVI data were obtained for 200-meter, 500-meter, and 1000-meter buffer distances around schools. To quantify adolescents’ daily screen time, a separate survey asked participants to report their non-school-related screen time during the week and on weekends over the previous month. Reported rates of less than two hours per day were classified as low screen time, while reports of two hours per day or more were classified as high screen time. Additional data was collected on a variety of other potentially influential factors, including participants’ grade level (middle or high school), gender, and self-reported socioeconomic status (SES), among several others. Data were statistically analyzed to examine if a relationship existed between greenness (NDVI) and depressive symptoms in relation to screen time.
Analysis revealed a significant protective relationship in which higher levels of greenness at all buffer distances around schools were linked to a lower risk of depressive symptoms among study participants. Further, while recreational screen time was related to depressive symptoms, the protective effect of green space on mental health remained when participants’ screen time was less than two hours. This finding suggests that higher levels of greenness at all buffer distances were linked to a significantly lower risk of depressive symptoms for participants who spent less than two hours a day engaged in screen-based activities. However, this protective relationship was not found when screen time was two hours or longer per day. No significant differences were detected based on participants’ gender. On the other hand, separate analyses for low SES and high SES participants revealed that the protective effect of green space on depressive symptoms was only significant for lower SES participants with less than two hours of screen time. A significant relationship was not detected between green space and depressive symptoms for study participants with higher SES, regardless of their screen time levels. This finding indicates that green space near schools may be more beneficial to the mental health of economically disadvantaged students than those from advantaged families.
Overall, the study revealed that higher levels of school greenness are linked to a lower risk of depression for adolescents who engage in less than two hours per day of recreational screen time. These findings suggest that while green spaces have a protective effect against depression in adolescents, there is still a need to control the amount of time adolescents spend on recreational screen time use and the researchers suggest that adolescents limit their non-school-related screen time to less than two hours per day.
Importantly, the study also revealed a potential equigenic effect in which the mental health of adolescents from economically disadvantaged families benefited more from the protective effect of school greenness, suggesting that school green spaces may improve health equity. The researchers conclude that schoolyard greening “may be a viable intervention to reduce health equity disparities and improve adolescent mental health.”
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