Obstructive sleep apnoea (OSA) is a condition in which, during sleep, the muscles of the throat relax and narrow, causing a blockage in the airway. During these episodes, the individual stops breathing, and sleep is disrupted. Although exact figures are not available, research suggests that up to 3.9 million people in the UK have a severe or moderate version of the condition (Sleep Apnoea Trust, 2020). Risk factors include being male, being overweight, being over 40 and having a large neck. The condition is usually diagnosed with polysomnography, which uses the respiratory disturbance index to measure the number of apnoeas (absence of airflow), hypopnoeas (restricted breathing), and abnormal respiratory events per hour of sleep.

OSA has associations with a number of clinical conditions: people with severe OSA, for example, are twice as likely to have a heart attack as those without (American Thoracic Society, 2013). OSA is also a risk factor for hypertension, stroke, atrial fibrillation and type 2 diabetes (Girardin et al, 2008).