Objective: To analyze the interfaces between mental illness, based on common mental disorder screening, and sociodemographic, health and life habits aspects of nursing workers at COVID-19 units. Method: A mixed methods study, carried out with 327 nursing workers from COVID-19 units of seven public and philanthropic, medium and large hospitals in Brazil. The collection included a socio-employment, health and lifestyle questionnaire, the Self-Reporting Questionnaire, and interviews. chi-square and Fisher’s exact tests were applied to quantitative data and thematic content analysis, with the help of NVivo in the qualitative ones. Results: Common mental disorders were screened in 35.5% of the sample and were associated with female sex (p = 0.004), age up to 40 years (p = 0.003), nurse (p = 0.014), reporting previous illness (p = 0.003), using psychoactive drugs (p < 0.001), medication that was not used before the pandemic (p < 0.001) and reporting poor sleep/eating quality (p < 0.001). The impacts of the pandemic on social and family life presented interfaces with mental illness. Conclusion: The presence of psychological illness is suggested, possibly associated with the repercussions of the pandemic on work and personal life.