Screen media use is associated with mental health problems among adolescents. However, few studies have examined screen media use using contemporaneous time diaries (rather than retrospective reports), compared associations across specific screen media activities or by gender, or examined associations with self-harm behaviors. Participants were 13- to 15-year-old adolescents completing time diaries (n = 4,252) for one weekday and one weekend day in the 2015 administration of the Millennium Cohort Study, a nationally representative birth cohort study of UK adolescents. Participants also completed a measure of depressive symptoms and reported whether they had engaged in self-harm in the last year. Girls who spent 2 + hrs/day, compared to < 2 h/day, on digital media were more likely to self-harm (for social media use, adjusted relative risk [ARR] for self-harm = 1.46, 95% CI = 1.17, 1.82; for internet use, ARR = 1.80 [1.20, 2.70]). Girls spending more time on digital media were also more likely to be depressed (for social media, ARR = 1.29 [1.03, 1.63]; for internet use, ARR = 1.75 [1.19, 2.59]). Associations with gaming, texting/e-mailing, and TV/video watching among girls were mostly not significant. Associations for boys were mostly not significant. Girls who use digital media (especially social media and the internet) more hrs/day are more likely to have clinically significant levels of depressive symptoms and prior history of self-harm, though gaming, texting/e-mailing, and TV/video watching showed few associations. Screen media use was mostly not significantly associated with self-harm or depression among boys.

屏幕媒体的使用与青少年的心理健康问题有关。然而，很少有研究使用同期日记（而不是回顾性报告）检查屏幕媒体的使用，比较特定屏幕媒体活动或按性别的关联，或检查与自残行为的关联。参与者是完成时间日记的 13 至 15 岁青少年（n = 4,252) 用于 2015 年千年队列研究管理中的一个工作日和一个周末，这是一项针对英国青少年的全国代表性出生队列研究。参与者还完成了对抑郁症状的测量，并报告了他们在去年是否进行过自残。与 < 2 小时/天相比，在数字媒体上花费 2 + 小时/天的女孩更有可能自我伤害（对于社交媒体的使用，自我伤害的调整后相对风险 [ARR] = 1.46，95% CI = 1.17, 1.82；对于互联网使用，ARR = 1.80 [1.20, 2.70]）。在数字媒体上花费更多时间的女孩也更容易抑郁（对于社交媒体，ARR = 1.29 [1.03, 1.63]；对于互联网使用，ARR = 1.75 [1.19, 2.59]）。女孩与游戏、短信/电子邮件和电视/视频观看的关联大多不显着。男孩的关联大多不显着。每天使用数字媒体（尤其是社交媒体和互联网）更多小时的女孩更有可能出现临床上显着的抑郁症状和自残史，尽管玩游戏、发短信/电子邮件和看电视/视频显示很少的关联。屏幕媒体的使用与男孩的自残或抑郁没有显着关联。