Untreated sleep disturbances and sleep disorders pose significant adverse daytime consequences and place children at considerable risk for poor health outcomes. Sleep disturbances occur at a greater frequency in children with acute and chronic medical conditions compared with otherwise healthy peers. Sleep disturbances in medically ill children can be associated with sleep disorders, comorbid with acute and chronic conditions, or secondary to underlying disease-related mechanisms, treatment regimens, or hospitalization. Clinical management should include a multidisciplinary approach with particular emphasis on routine, regular sleep assessments and prevention of daytime consequences, and promotion of healthy sleep habits and health outcomes.