These variables of anxiety, self-efficacy, stress, sleep quality, and social support and their interactions can be analyzed by structural equation modeling (SEM), which is a multivariate analysis method to determine the structural relationship between measured variables. Therefore, this observational study, conducted at the Wuhan University School of Medicine, China, aimed to use SEM to determine the effects of social support on sleep quality and function of medical staff who treated patients with COVID-19 in January and February 2020. The two assumptions made in this observational study were that the social support given to the medical staff directly affected their sleep quality, and that social support affected sleep quality by reducing anxiety and stress and by increasing self-efficacy as intermediate variables.