Brain tumours are among the most common cancer diagnoses in paediatrics. Children with brain tumours are at risk of developing sleep problems because of direct and indirect effects of the tumour and its treatment, in addition to psychosocial and environmental factors. Sleep has an important role in physical and psychological wellbeing, and sleep problems are associated with many adverse outcomes. In this Review, we describe the state of the evidence regarding sleep in people with paediatric brain tumours, prevalence and types of sleep problems, risk factors, and effectiveness of interventions. Evidence shows that sleep problems, particularly excessive daytime sleepiness, are common in people with paediatric brain tumours, with high BMI emerging as a consistent predictor of sleep disruption. Further intervention studies are needed, and clinical evaluation of sleep is warranted for people with paediatric brain tumours.