Diverse Platforms, Diverse Effects: Evidence From a 100-Day Study on Social Media and Adolescent Mental Health

Today, around 182 million adolescents globally face mental health challenges (Institute of Health Metrics and Evaluation, 2020; World Health Organization, 2023), with the prevalence of such issues on the rise (Keyes & Platt, 2024). Accordingly, the World Health Organization has prioritized adolescent mental health. Three dimensions of mental health are pivotal to promote in this context: affective well-being (i.e., the prevalence of experiencing positive emotions, such as happiness, over negative emotions, such as sadness, Kross et al., 2021) - from here on well-being -, self-esteem (i.e., having a positive and relatively stable evaluation of oneself, Rosenberg, 1965), and having close friendships (Raboteg-Saric & Sakic, 2014). For these dimensions of mental health, social media play an important, yet debated role. While some argue that social media are harmful for adolescent mental health, others suggest it could have benign or even beneficial effects (Haidt, 2020; Shankleman et al., 2021; Twenge et al., 2022). In fact, review studies and meta-analyses have shown that the effect of social media on mental health can be harmful, beneficial, or negligible, depending on which dimension of mental health is being studied (Hancock et al., 2022; Liu et al., 2016; Saiphoo et al., 2020). Furthermore, recent within-person studies have revealed that the effects of social media use on mental health differ from person to person (Beyens et al., 2021; Pouwels et al., 2021; Valkenburg et al., 2021). Yet, to date, no research has systematically explored how a single individual may experience differential impacts from social media use on different dimensions of mental health, while this knowledge is vital for developing more targeted and effective interventions. Therefore, the aim of this study is to examine social media’s potential differential within-person effects on adolescents’ well-being, self-esteem, and friendship closeness. First, we will determine how many adolescents in our sample experience “within-person unity” (i.e., uniform effects across all three dimensions) versus “within-person duality” (i.e., differential, contrasting effects). Specifically, we will conduct an in-depth examination of the types of within-person unity and duality that adolescents experience. We will distinguish between three types of within-person unity: (1) uniformly positive effects, (2) uniformly negative effects, and (3) uniformly null effects. For within-person duality, we will identify three patterns: (1) two positive effects and one negative effect, (2) two negative effects and one positive effect, and (3) one positive effect, one negative effect, and one null effect. Second, we will explore how the three types of unity and three types of duality differ in terms of age, gender, and self-concept clarity (SCC) to understand which adolescents are more likely to experience within-person unity or duality.