Background/Objective: Associations between adolescents' sleep and their media consumption have been shown in several cross-sectional studies. However, longitudinal investigations are still sparse and have mainly investigated associations between sleep duration and the usage of TV or computer games. The present study explored reciprocal longitudinal relationships between the consumption of different screen-based media and sleep-related problems in German adolescents. Participants: Four hundred sixty-seven 10- to 17-year-old adolescents participated in the LIFE Child Study in Leipzig, Germany. Methods: The consumption of screen-based media (TV or video, computer and Internet, mobile phones) as well as sleep-related problems (problems at bedtime, sleep behavior problems, daytime sleepiness) were assessed at two time points, 12 months apart. Reciprocal longitudinal relations were assessed by multiple regression analyses. All associations were controlled for age, gender, socioeconomic status, and dependent variables at baseline. Results: The consumption times of the different screen-based media were significantly related. Similarly, the different sleep-related problems showed significant interrelations. Most importantly, the analyses revealed significant associations between a high baseline consumption of computer and Internet with more problems at bedtime, as well as more daytime sleepiness at follow-up. Furthermore, baseline daytime sleepiness was associated with a higher consumption of TV or video at follow-up. Conclusions: These results indicate a mutual dependency of media consumption and sleep over time.