Abstract
<title>Abstract</title> <p>Introduction: Adolescence and emerging adulthood involve developmental changes in peer orientation and self-regulation that may shape associations between digital media use and well-being. This study examined whether associations between regular platform use, psychological distress, and smartphone-related behavioral dysregulation differed across these developmental periods. Methods We analyzed cross-sectional survey data collected in Germany in 2024 from a nationwide sample of 2,042 individuals aged 14–29 years, of which 50% were male, 49% were female, and fewer than 1% identified as non-binary. Structural equation models examined associations between regular use of Instagram, TikTok, Telegram, and WhatsApp, psychological distress, and smartphone-related behavioral dysregulation. Models were estimated separately for adolescents (14–18 years), younger emerging adults (19–23 years), and older emerging adults (24–29 years). Results Regular Instagram and TikTok use showed the largest direct associations with smartphone-related behavioral dysregulation in the full sample, whereas psychological distress was positively associated with behavioral dysregulation across all age groups. Adolescents showed the broadest pattern of significant platform-specific associations, and the age-stratified model explained the greatest proportion of variance in this group. Conclusions The findings highlight the importance of distinguishing between individual social media platforms across developmental periods. Most associations between platform-specific social media use, psychological distress, and smartphone-related behavioral dysregulation were broadly similar across adolescence and emerging adulthood. These results underscore the value of considering both platform-specific engagement and broader difficulties in behavioral self-regulation when examining the role of digital media in young people's psychosocial development. Clinical trial registration Not applicable.</p>