Hongjian Cao, Kunru Song, Yao Zheng, Yue Liang, Yuan-Wei Yao, Nan Zhou
Loneliness and problematic social media use (PSMU) are two modern epidemics worldwide, which are often comorbid and prevalent among young adults. The design of everyday interventions calls for scientific endeavors that address how they may reciprocally influence each other on microtimescales and identify modifiable mechanisms. Using a 30-day daily diary design, this study examined the link between loneliness and PSMU among 209 Chinese young adults (M = 20.95 years old, 51.2% female), with psychological distress symptoms (PD) tested as a mediator and mindfulness and self-compassion explored as buffers. Results of dynamic structural equation modeling analyses indicated reciprocal positive associations between loneliness and PSMU across days at within-person level. PD mediated such associations, with a stronger indirect effect from PSMU to loneliness (vs. reverse) through PD. At between-person level, mindfulness and self-compassion attenuated the cross-day indirect effect from PSMU to loneliness (rather than reverse) via PD by buffering the same-day positive association of PSMU with PD. Between-person mindfulness and self-compassion also alleviated the same-day positive association between loneliness and PD, but no significant conditional indirect effects emerged for the cross-day pathway from loneliness to PSMU through PD. At within-person level, although self-compassion (rather than mindfulness) buffered the same-day positive association of PSMU (or loneliness) with PD, no conditional cross-day indirect effects emerged. These findings provide insights into how and why young adults' daily loneliness and PSMU perpetuate each other. Improving young adults' mindfulness and self-compassion skills and reducing their PD could help diminish vicious cycles of daily loneliness and PSMU. (PsycInfo Database Record (c) 2026 APA, all rights reserved).