Maartje Boer

THE COMPLEX ASSOCIATION BETWEEN SMU AND WELLBEING 235 8 are integrated into the daily lives of many young people, both very little as well as excessive SMU may be harmful to wellbeing. Adolescents who barely use social media may miss out on social information and interaction with peers, while adolescents who use social media excessively may displace meaningful offline activities to online activities. In contrast, moderate SMU may not be harmful and could even be advantageous to adolescent wellbeing (Przybylski & Weinstein, 2017). Therefore, the association between SMU intensity and wellbeing may show an inverted u-shape. Cross-sectional research supports this hypothesis by showing that adolescents who do not use social media and those who use it excessively report lower levels of happiness and overall mental wellbeing than those who use it moderately (Przybylski & Weinstein, 2017; Twenge, Martin, et al., 2018). However, longitudinal research does not support this hypothesis. Specifically, a longitudinal study on the association between overall screen time and depressive symptoms did not find any differences in the association across groups of adolescents below or above certain thresholds of screen time (Houghton et al., 2018). In addition, an experience sampling study did not yield curvilinear associations over time between several social media activities and depression or worry, except for active SMU: In line with the Goldilocks hypothesis, on days when adolescents did not create or created a lot of content on social media, they reported increased depressive symptoms, whereas on days when they created some content, they reported decreased depressive symptoms (Jensen et al., 2019). Nevertheless, the researchers emphasized that this finding should be interpreted with caution, because very few adolescents created a lot of content on one day (Jensen et al., 2019). Thus, while cross-sectional research supports the Goldilocks hypothesis, longitudinal and experience sampling studies hardly replicate these findings. The Association Between SMU Intensity and Wellbeing Depends On Individual Differences Some adolescents may be negatively affected by high SMU intensity, some positively, and some may not be affected at all. Therefore, researchers increasingly advocate for studying heterogeneity in the association between adolescents’ SMU intensity and wellbeing (Beyens, Pouwels, Valkenburg, et al., 2020; Odgers et al., 2020; Orben, 2020a). According to the Differential