What is Sleep APNOEA?

Sleep APNOEA is a temporary suspension of breathing which occurs repeatedly during sleep. It often affects overweight people or thosehaving an obstruction in the breathing tract, an abnormally small throat opening, or a neurological disorder. 

Obstructive Sleep Apnoea-Hypopnoea Syndrome (OSAHS) is a sleep disorder in which a person has irregular breathing at night and is excessively sleepy during the day. 

In sleep apnoea, the upper airway (pharynx) collapses repeatedly, at irregular intervals, during sleep. Apnoea is when the airway collapses and is blocked completely, cutting off the flow of air. Hypopnoea occurs when the collapse is only partial. The airway is reduced and the person will experience hypoventilation (inadequate breathing). 

The pause in breathing, or period of very restricted breathing, is usually defined as about 10 seconds, although it varies from person to person. The frequency of apnoea or hypopnoea is used to assess the severity of this condition. The number of times that the apnoea occurs in an hour is called the apnoea/hypopnoea index (AHI) or the respiratory disturbance index (RDI). An AHI of between 5 and 14 in an hour is mild sleep apnoea. Between 15 and 30 is moderate. More than 30 in an hour is severe – that means at least one every two minutes. 

As people with sleep apnoea fall asleep, the muscles in their airway relax. The collapsing of the airway (pharynx) causes people to come out of deep sleep and either wake momentarily or sleep lightly, as they are trying to breathe more deeply. The person soon resumes deep sleep, and the cycle begins again. The period of wakefulness is so brief that even though it may happen hundreds of times a night, the person usually won’t remember waking up. 

Sleep apnoea affects around one in 100 people. Overweight men between the ages of 30 and 65 are most commonly affected, but it may also occur in children with enlarged tonsils or adenoids.

Information source: NHS Direct Online Health Encyclopedia, 2005