Effects of Pre-Bedtime Social Media Use on Objective and Subjective Sleep Quality in Adolescents and Young Adults

Using smartphones, particularly social media, before bedtime has emerged as a concern for sleep. While previous research has predominantly focused on total screen time or light exposure, less is known about content-specific effects. Furthermore, most studies rely on self-reported data. This study investigated the impact of objectively assessed (Murmuras app) pre-bedtime social media use (in the 2 h before lights off) on subjective (daily sleep logs) and objective (actigraphy) sleep measures. Twenty-three healthy male participants (14-25 years) completed 14 consecutive days of measurements, including nine home nights and four standardised laboratory nights with no social media use. Main analyses were restricted to home nights with non-zero social media use. Results showed that longer pre-bedtime social media use was associated with reduced sleep efficiency, a trend toward shorter sleep duration, and more awakenings and greater sleep fragmentation only on weekends. For subjective sleep, longer social media use was associated with a stronger feeling of having slept deeply, independent of day type; participants also generally perceived weekend nights as better sleep nights than weekdays, irrespective of social media use. In contrast to the weekend-specific objective impairments, no day-type-specific interaction emerged for any subjective parameter, suggesting that participants did not subjectively detect the actigraphy-measured sleep disruptions. This objective-subjective dissociation underscores the need for both objective and subjective measures in sleep research. Future research should examine specific engagement types (e.g., active vs. passive), in-bed use, and underlying mechanisms to better understand when and for whom social media use affects sleep.