The present study aimed to understand the effects of a one-week break from social media 3(SM) (Facebook, Instagram, Twitter, and TikTok) on wellbeing, depression, and anxiety 4 compared to using SM as usual. We also aimed to understand whether time spent onplatforms mediates the relationship between SM cessation and wellbeing, 6 depression, and anxiety. We randomly allocated 154 participants (mean age of 29.6 years) 7 to either stop using SM (Facebook, Twitter, Instagram, and TikTok) for one-week or continue 8 to use SM as usual. At one-week follow-up, significant between-group differences in 9 wellbeing (mean difference (MD) 4.9, 95% confidence interval (CI) 3.0 to 6.8), depression 10 (MD -2.2, 95% CI -3.3 to -1.1), and anxiety (MD -1.7, 95% CI -2.8 to -0.6) in favour of the 11 intervention group were observed, after controlling for baseline scores, age, and gender. The 12 intervention effect on wellbeing was partially mediated by a reduction in total weekly self-13 reported minutes on SM. The intervention effect on depression and anxiety was partially