Association of Bedtime with both Suicidal Ideation and Suicide Planning among Korean Adolescents

In comparison to other countries, the South Korean population has a short average sleep duration, and studies have suggested that insufficient sleep is a risk factor for suicidal behavior. This study aimed to examine the association of bedtime with suicidal ideation and with suicide planning, respectively, among Korean adolescents. This study included 48,218 participants from the 2017 Korea Youth Risk Behavior Web-based Survey. Participants were divided into three categories: pre-23:00 bedtime, 23:00-01:30 bedtime, and post-01:30 bedtime. Suicidal ideation and suicide planning were the main dependent variables, and multiple logistic regression analysis was performed to examine the target association. For both male and female respondents, compared to those who had a pre-23:00 bedtime, those whose bedtime was after 01:30 were more likely to have suicidal ideation (post-01:30 bedtime for men: OR = 1.29, 95% CI = 1.16-1.45; for women: OR = 1.32, 95% CI = 1.20-1.44). For suicide planning, the results were also significant for both genders (post-01:30 bedtime for men: OR = 1.41, 95% CI = 1.16-1.70; for women: OR = 1.21, 95% CI = 1.03-1.43). Odds of suicidal ideation were higher for those who had a post-01:30 bedtime on weekdays but not weekends. We found that, among adolescents, going to bed after 01:30 is significantly associated with suicidal ideation and suicide planning, after adjusting for demographic, socioeconomic, and health-related characteristics. Therefore, late bedtime should be the timepoint of a suicide intervention for adolescents, in order to prevent developing suicidal ideations and suicide planning.