Social media use duration and epigenetic aging among U.S. adults in the MIDUS refresher study

Social media platforms are central to daily social interaction, with emerging evidence linking higher engagement to adverse outcomes, including increased stress, sleep disturbance, and depressive symptoms. However, whether these digital exposures translate into measurable acceleration of biological aging remains unexplored, particularly among midlife and older adults. We analyzed cross-sectional data from 323 participants (Mean age = 47.5 years, SD = 11.8) in the Midlife in the United States Refresher Study who completed daily diary assessments of social media use duration and provided blood samples for epigenetic aging measurement. Epigenetic aging was quantified using DunedinPACE and GrimAge2 from genome-wide DNA methylation analysis. In a linear regression model controlling for differences in inter-assessment intervals, sociodemographic characteristics, health behaviors, and self-reported mental health, each additional hour of daily social media use was significantly associated with a 0.19-SD higher DunedinPACE score (95% CI: 0.08 to 0.29, p < 0.001). However, further adjustment for body mass index attenuated this association (0.09 SD increase, 95% CI: -0.01, 0.19, p = 0.088), suggesting that BMI may reflect the downstream consequences of broader behavioral, metabolic, psychosocial, environmental, and health-related processes relevant to the observed relationship. No associations were observed with GrimAge2 across any model. These findings provide preliminary evidence that social media use duration is associated with the pace of biological aging as measured by DunedinPACE. Future research should employ longitudinal designs with direct measurement of digital engagement, behavioral and psychosocial processes, and physiological mechanisms to clarify how digital environments may relate to biological aging over time.