Trauma experience increases the risk of suicidal ideation, but little is known about potentially psychological mechanisms underlying this relationship. This study aims to examine the relationship between coronavirus disease 2019 (COVID-19)-related traumatic event (CTE) exposure and suicidal ideation among hospital workers, and identify mediating roles of sleep disturbances in this relationship.Workers in seven designated hospitals in Wuhan, China, were invited to participate in an online survey from May 27, 2020, to July 31, 2020. Participants completed a self-report questionnaire to evaluate demographic characteristics, level of CTE exposures, nightmare frequency, insomnia severity, symptoms of depression and anxiety, and suicidal ideation. A series of correlation analyses were performed, and a mediation model was generated to examine correlations between CTE exposure, sleep disturbances, and suicidal ideation.A total of 16,220 hospital workers were included in the final analysis, 13.3% of them reported suicidal ideation in the past month. CTE exposure was significantly associated with insomnia severity, nightmare frequency, and suicidal ideation. After controlling potential confounders, nightmares but not insomnia, depression, or anxiety were shown to be independent risk factors for suicidal ideation. Pathway analyses showed that the relationship between CTE exposure and suicidal ideation was fully mediated by nightmares (proportion mediated 66.4%) after adjusting for demographic characteristics and psychological confounders.Cross-sectional design precluded the investigation of causal relationships.CTE exposure increases risk of hospital workers' suicidal ideation that is mediated by nightmares, suggesting nightmares intervention might be considered as a component when developing suicide prevention strategies.Copyright © 2022. Published by Elsevier B.V.