The cessation of breathing for ten seconds or more during sleep. Such episodes affect around 5 per cent of adults and are markedly more common in men, especially if they are obese; it may occur as frequently as 400 times per night. It can be due to a failure of the physiological drive to breathe, initiated in the brain-stem (central sleep apnoeas), but is more often due to a transient obstruction of the airway between the level of the soft PALATE and the LARYNX (obstructive sleep apnoeas), when the airway dilator muscles over-relax. Any factor such as alcohol or sedative drugs that accentuates this, or that makes the airway narrower (such as obesity or large TONSIL) will tend to cause sleep apnoeas.

Vigorous respiratory movements are made in order to overcome the obstruction during each apnoea. These are associated with snoring and snorting noises. The apnoea ends with a mini-arousal from sleep. As a result, sleep becomes fragmented and sleep deprivation, with sleepiness during the day, is common. This may result in accidents – for instance, at work or while driving – and sleep apnoea is also linked with an increased risk of STROKE, heart attack and HYPERTENSION.

The diagnosis of sleep apnoea is made by linking specially designed software with ELECTROCARDIOGRAPHY and monitoring of respiratory rate and movements performed during video-observed sleep, with minimal disturbance of the subject.

Initial treatment is directed at correcting the cause (e.g. obesity), but if the apnoeas persist or are severe, a nasal mask and pump, which introduces air under slight pressure into the upper airway (CONTINUOUS POSITIVE AIRWAYS PRESSURE, CPAP), is generally effective.