The prevalence of obstructive sleep apnoea in its severe form is about 2% and 0.5% in middle aged men and women respectively.1 Pharyngeal collapse during sleep causes recurrent frustrated inspiratory efforts, oscillating levels of blood oxygen, and disturbed sleep, which may, or may not, lead to excessive daytime sleepiness.2 The main treatment for moderate to severe obstructive sleep apnoea and excessive daytime sleepiness (obstructive sleep apnoea syndrome) is nasal continuous positive airway pressure applied during sleep. A meta-analysis3 clearly showed that this treatment is highly effective in preventing apnoea in such patients, thus relieving symptoms and improving self assessed quality of life.4

The main debate over treatment is whether obstructive sleep apnoea is also an important independent risk factor for vascular disease (such as myocardial infarction, heart failure, and stroke), both in those with and without current vascular problems. Some of the potential …