This study investigated the association between work stress and sleep disturbance among Korean workers, focusing on the mediating effects of somatic and cognitive pre-sleep arousal symptoms. Data were derived from the “Korean Work, Sleep, and Health Study (KWSHS),” involving 4,393 participants. Work stress was assessed using the Korean Occupational Stress Scale, and sleep disturbances were measured using the Insomnia Severity Index and Pittsburgh Sleep Quality Index. The Pre-Sleep Arousal Scale was utilized for assessing pre-sleep arousal status. For statistical analyses, the χ² test, logistic regression analysis, and mediation analysis were used. Mediation analysis revealed that somatic pre-sleep arousal predominantly mediated the relationship between hazardous physical environments and insomnia symptoms (52.5%), while cognitive pre-sleep arousal was the primary mediator for high job demands (48.0%), organizational injustice (48.6%), and job insecurity (46.6%). These findings suggest that somatic and cognitive pre-sleep arousal serve distinct mediating roles in the relationship between specific types of work stress and sleep disturbances.