Background: The diagnosis of cancer, chemotherapy, radiotherapy and surgical treatment cause sleep disorders in the short and long term. In children with cancer, sleep disorders are reported between 12.4-31%. Sleep plays a fundamental role in the psychological health, neurocognitive ability and health-related quality of life. It is more important in children with pain, anxiety and emotional stress. Both disease and treatment-related physical and emotional disorders and the mechanism of coping affect sleep. Homeostatic, cardio-respiratory, neurological and behavioral mechanisms playing role in sleep regulation and circadian rythm disturbance cause sleep disorders in children with cancer. The causes of sleep disorders were determined to be hunger, nausea, vomiting, frequent needing to use the bathroom, nightmares, fatigue, pain, drug treatment, hospital admission and noise and light in the hospital. It has also been reported that the use of steroids in some patients sleep disorders. Cancer can have either direct effects on sleep whereby the physical presence of a tumour causes brain injury, or indirect effects, including those due to treatment stress, neurosurgery, hydrocephalus, chemotherapy, cranial radiation therapy, pain, fatigue, endocrinopathies or organ damage. Cancer also affects sleep by disrupting the normal circadian rhythm of the sleepwake cycle. But the mechanisms that explain this issue are insufficient. Circadian rhythms are biological cycles of physiological and behavioral processes. Sleep disorders reduce the quality of life for children and lead to behavioral and cognitive problems as a result of the deterioration of physiological growth, endocrine system, natural killer cell and cytokine activity in children and adolescents.