Objective: This cross-section study investigated the prevalence of sleep disorders and the relationship between sleep problems (insomnias, parasomnias, and daytime sleepiness) and school refusal behavior in school-age children (fourth grade elementary school in Cologne, Germany). Method: A sample of 1,490 children (age range: 8-11 years) and their parents each completed a sleep questionnaire and the School Refusal Assessment Scale. Results: The results indicate that sleep problems in childhood are frequent. Furthermore, the results of the study clearly indicate that there is a relationship between sleep problems and school refusal behavior. Children suffering from insomnias (sleep onset problems, difficulties maintaining sleep), parasomnias (nightmares, night terrors), and daytime sleepiness showed without exception significantly higher scores in 3 out of 4 school refusal behavior maintaining conditions compared to children without sleep problems. These three conditions are all associated with anxiety disorders (anxiety or depressive disorder, as well as separation anxiety disorder). Only in the fourth condition, which is associated with oppositional defiant or conduct disorders, truancy, or no disorder at all, were there no significant differences between children with and children without sleep problems. Conclusions: For research and clinical practice, it is important to view sleep problems and school refusal behavior in relation to each other rather than as isolated phenomena.