Association of Sleep Duration and Working Hours with Suicidal Ideation in Shift Workers: The Korean National Health and Nutrition Examination Survey 2007–2018

OBJECTIVE: This study investigated whether sleep duration and working hours were associated with the risk of suicidal ideation. METHODS: Data from 13,628 shift workers (age ≥19) were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys conducted in 2007–2018. We included healthy shift workers without depressive disorders and chronic medical illnesses. Sleep duration, working hours, and suicidal ideation were assessed using a self-reported questionnaire. Logistic regressions were used to examine the association of sleep duration and working hours with the risk of suicidal ideation. We examined interactions between sleep duration and working hours in association with suicidal ideation. In addition, interactions of sex or age were also analyzed. RESULTS: Shift workers sleeping for <6 and ≥10 hours/day were associated with suicidal ideation compared with those sleeping for 7 to <9 hours/day. Individuals working >52 hours/week had a higher risk of suicidal ideation compared with those working ≤40 hours/week. In terms of interaction by sex or age groups in the association between working hours and the risk of suicidal ideation, the relationship was stronger for men than for women and for those aged <45 years than for those aged ≥45 years. CONCLUSION: Shorter or longer sleep durations, and long working hours were associated with a higher risk of suicidal ideation. Under long working hours, male shift workers or those aged <45 years were more vulnerable to suicidal ideation.