PeerScreen Trial - Reducing Screen Media Use in Peer-groups of Young People

The purpose of the PeerScreen trial is to investigate whether reducing screen media use affects mental health, social interaction, sleep, physical activity, heart rate variability, and behavioral patterns in young people aged 13 to 24 years. The primary question the trial aims to answer is: Does reducing screen media use over a 4-week period improve mental health among young people? Researchers will compare a screen media reduction intervention with a control condition in which participants continue their usual screen media use to determine whether reducing screen media use leads to improvements in mental health. Participants will: * be allocated to either a 4-week screen media reduction intervention or a control condition * complete a study protocol including questionnaire-based assessments, daily self-reports, and objective monitoring of screen media use, sleep, physical activity, heart rate variability, social interactions, and geolocation