Background Insomnia is one of the most common sleep disorders, and it frequently co‐occurs with several other psychiatric conditions. The relationship between insomnia and eating disorders is supported by clinical evidence indicating that patients with eating disorders experience poor sleep even if they rarely complain of it. Furthermore, indirect evidence comes from studies indicating that poor sleep predicts obesity and several studies also evidence that restrictive‐type eating disorders are associated to objective reduction of sleep quality. Methods One thousand nineteen female university students volunteered for participating to the study. Valid and reliable questionnaires were used and the mediating role of depressive mood assessed. Results Evidence was found that increased severity of insomnia is associated with higher severity of disordered eating. Both insomnia and disordered eating symptoms were related to depression. The mediation analysis evidenced that both the direct path linking insomnia symptoms and eating disorder symptoms are significant and also the indirect paths related to the mediation of depression. Conclusions These findings support the existence of both a direct and an indirect relationship between insomnia symptoms and eating disorder symptoms.