Sleep apnoea: causes, consequences and treatment.

An awakening has taken place over the last 25 years to the science of sleep disorders. Foremost amongst these, both in the medical world and the public eye, has been Sleep Apnoea Syndrome (SAS). The prevalence is thought to be the order of 1-2%. Males are eight times more commonly affected than females, although after the menopause the gap narrows considerably. Sleep apnoea occurs in children, usually in relation to large tonsils and adenoids, but in adult life patients usually present between the age of 40 and 60 and the prevalence increases with age. Numerous apnoeas or hypopnoeas during the night's sleep result in disordered sleep architecture and unrefreshing sleep. This is usually accompanied by night-long snoring which may lead to marital discord and even complaints from neighbours. Symptoms on waking may be a headache and a feeling of not being refreshed by sleep. Sleepiness during the day can interfere with work and social activities and may produce risks to the patient and others if it occurs while operating dangerous machinery or driving. Over a longer time scale SAS results in intellectual and memory deterioration, a higher incidence of ischaemic heart disease, hypertension, polycythemia and pulmonary hypertension. Right heart failure is particularly likely if there is chronic airflow obstruction contributing to a low arterial oxygen level. Asystolic periods and tachyarrhythmias may occur during apnoeic periods. The increased mortality of SAS relates to coronary and cerebrovascular disease and arrhythmias. Sudden death occurs with greater frequency in patients with SAS, mainly at night.