Background: The dose-response association between sedentary time and suicidal ideation and planning among adolescents is unclear. This study examined the association between leisure sedentary time and suicidal ideation, planning and attempts among adolescents in low- and middle-income countries (LMICs).

Methods: We used the most recent data (2009-2016) from the Global School-based Student Health Survey (GSHS) in 54 LMICs. Leisure sedentary time and suicidal ideation, planning and attempts were assessed using a standardized questionnaire. A total of 146,345 young adolescents aged 12-15 years were included.

Results: Among adolescents in the 54 LMICs, the prevalence of suicidal ideation was 14.8%, planning was 14.5%, and attempts was 13.0%. Compared with those who had less than 1 h/day of sedentary time, those who had 3, 4 h/day sedentary time were at higher odds ratio (OR) of suicidal ideation OR=1.21 (95% confidence interval (CI) =1.14-1.29), planning OR=1.15 (95%CI=1.07-1.22) and attempts OR=1.17 (95%CI=1.09-1.26), and those who had more than 8 h/day sedentary time were at OR=1.58 (95%CI=1.44-1.72), OR=1.44 (95% CI=1.31-1.58) and OR=1.27 (95%CI=1.16-1.40), respectively.

Limitations: Suicidal behaviors and sedentary time were assessed by a self-reported questionnaire, which might be prone to recall bias.

Conclusions: Higher amounts of leisure sedentary time are associated with suicidal ideation, planning and attempts among adolescents. Adolescents should spend less than 2 h/day of their sedentary time to reduce the likelihood of suicide.