Obstructive sleep apnoea (OSA) is characterised by repetitive episodes of upper airway obstruction during sleep and represents the most common sleep disorder in childhood. OSA affects approximately 2%-5% of children with peak prevalence between the age of 2 and 6 years due to the hypertrophy of the adenoids and/or the tonsils and is associated with a decrease in sleep quality and quality of life due to arousals, a decrease in sleep efficiency and a disruption of the physiological sleep architecture. OSA is significantly more common and severe in children with underlying disorders. For these children, adenotonsillectomy, which is the first line treatment in the general population, is often not sufficient to cure OSA. Other maxillofacial and, or, neurosurgical interventions, and, or non-invasive ventilation may then be necessary to relieve the airway obstruction during sleep. Sleep may thus be stressful for these children with severe OSA. Our experience has revealed that the perception of the child's sleep quality by caregivers and healthcare professionals may be erroneous. Assessing the child's