Digital media use and subsequent self-harm during a 1-year follow-up of Chinese adolescents

Background: Excessive digital media use is prevalent and has a negative impact on sleep, daytime functioning, and mental health in adolescents. We examined the prospective associations between digital media use and subsequent suicidal and non-suicidal self-harm. Methods: Shandong Adolescent Behavior & Health Cohort (SABHC) is a longitudinal study of adolescent behavior and health in Shandong, China. Participants included for the analysis were 7,072 SABHC adolescents who were initially assessed in 2015 and were reassessed in 2016. A self-administered structured questionnaire was used to measure digital media use (i.e., television watching, internet use, and mobile phone use) on weekdays and at the weekend, mental health, and self-harm. Results: Multivariable logistic regression analyses showed that daily internet use >= 2 h on weekdays (odd ratio (OR) = 1.86, 95% confidence interval(CI) = 1.25-2.76) and >= 3 h at the weekend (OR = 1.46, 95%CI = 1.06-2.00) and daily mobile phone use 2-3 h (OR = 1.46, 95%CI = 1.02-2.10) and >= 4 h (OR = 1.74, 95%CI = 1.20-2.51) at the weekend were significantly associated with increased risk of recurrent self-harm. Daily internet use >= 2 h on weekdays (OR = 1.81, 95%CI = 1.20-2.74) and >= 3 h at the weekend (OR = 1.55, 95%CI = 1.12-2.15), daily mobile phone use 1-2 h on weekdays (OR = 1.47, 95%CI = 1.02-2.12) and 2-3 h (OR = 1.49, 95%CI = 1.01-2.19) and >= 4 h (OR = 1.93, 95%CI = 1.31-2.85) at the weekend were significantly associated with increased risk of recurrent non-suicidal self-injury. Daily internet use 1-2 h on weekdays and 2-3 h at the weekend were significantly associated with increased risk of new suicide attempt (OR = 1.80, 95%CI = 1.07-3.03) and recurrent suicide attempt (OR = 6.26, 95%CI = 1.31-29.88), respectively. Limitations: All data were self-reported. Conclusions: Excessive use of internet or mobile phone appears to be a significant risk factor of self-harm, suggesting that limiting adolescent use of internet and mobile phone may be beneficial to reduce risk of self-harm.