Abstract
Studies examining the associations between social media use and subjective well-being have revealed inconsistent results and mainly refer to the between-person level. We conducted a 14-day diary study among 200 youths ages 10 to 14 to examine within- and between-person associations of social media use (Instagram, TikTok, and YouTube), subjective well-being (positive/negative self-worth, positive/negative affect), and upward social comparisons (general impression of others being better off). Multilevel structural equation models showed that social media use was linked to lower positive and higher negative self-worth on a daily basis, and that upward social comparisons were linked to diminished subjective well-being on all dimensions. Furthermore, our findings were consistent with (partial) mediation of the effect of social media use on subjective well-being by upward social comparisons on the between- and within-person levels. Youths' feelings that others are better off than themselves may help explain part of the heterogeneity of previous findings.