Obstructive sleep apnoea (OSA) is a medical condition in which children have breathing difficulties when they are asleep. When children (and adults) fall asleep, their muscles relax. This can lead to a floppy upper airway which can become either partly or totally blocked by the adenoids and tonsils when the child is asleep. The parent may notice snoring and pauses in the child's breathing while the child is sleeping. Snoring in children is quite common - about 15 to 20 children in every 100 will snore. OSA is less common - about two to three children in every 100. OSA disrupts sleep. Children who have OSA may feel tired in the day, may have problems with learning, behavioural and/or medical problems.