Job strain, derived from high psychological demands and low job control, is associated with insomnia, but information on the role of emotional demands and social support in this relationship is scarce. The aims of this study were (i) to test the association between job strain and self-reported insomnia symptoms, (ii) to evaluate the combination of emotional demands and job control regarding insomnia symptoms, and (iii) to analyze the influence of social support in these relationships. This cross-sectional study refers to a sample of nurses (N = 3,013 and N = 3,035 for Job Strain and Emotional demand-control model, resp.) working at public hospitals in Rio de Janeiro, Brazil. Data were collected through a self-report questionnaire. The prevalence of insomnia symptoms was 34.3%. Job strain was associated with increased odds for insomnia symptoms (OR: 2.20); the same result was observed with the combination of emotional demands and low job control (OR: 1.99). In both models, the inclusion of low social support combined with high demands and low job control led to increased odds for insomnia symptoms, compared to groups with high social support from coworkers and supervisors. Besides job strain, the study of emotional demands and social support are promising with regards to insomnia symptoms, particularly among nurses.