The effect of social media use on mental health of college students during the pandemic
利用疫情前后追踪数据，发现社交媒体在疫情后期对大学生心理健康有显著负面影响，尤其对社交孤立学生影响更大，而社会支持和心理韧性可起到保护作用。
Social media is viewed to be a key contributor to worsening mental health in adolescents, as most recently reflected in a public health advisory by the US Surgeon General. We provide new evidence on the causal effects of social media on mental health of college students during the Covid-19 pandemic, exploiting unique, longitudinal data collected before the Covid-19 pandemic began and at two points during the pandemic. We find small insignificant effects of social media 4 months into the pandemic during a period of social distancing, but large statistically significant negative effects 18 months into the pandemic when colleges were mostly back to normal operations. Using rich data on substance use, exercise, sleep, stress, and social support, we find some evidence of substitution away from activities that better support mental health at later stages of the pandemic but not at early stages. We find that the negative effects of social media are mostly concentrated among socially-isolated students. Both social support and resilience protect students from the negative effects of social media use. Policy implications include regulating social media while also bolstering social support and resilience as important protective factors.