Obstructive sleep apnoea (OSA) is a condition caused by repeated upper airway obstruction during sleep, due to narrowing of the upper airway. It occurs when the muscles controlling the upper airway relax during sleep, resulting in a collapse or narrowing of the airway. This causes oxygen levels in the blood to decrease.
The Apnoea Hypopnoea Index (AHI) represents the number of apnoea (pauses in breathing) and hypopnoea (reduction in breathing) events per hour of sleep during your sleep study, and indicates the severity of your sleep apnoea.
