What is Sleep Apnoea?

Sleep apnoea, sometimes referred to by its US spelling, sleep apnea, is a condition that affects your breathing during sleep. The condition results in disturbed nights and poor-quality sleep that can have a considerable impact on your health and wellbeing (and that of your sleeping partner!).

Sleep apnoea is a form of Sleep Disordered Breathing (SDB). Obstructive Sleep Apnoea (OSA) is when air stops flowing to the lungs because of a blockage (or an obstruction) in the upper airway. When your brain stops sending signals to your breathing muscles during sleep; this is Central Sleep Apnoea (CSA). Or it could be a combination of the two, also known a mixed or complex Sleep Apnoea.

OSA is by far the most common form making up 84% of all sleep apnoea diagnoses.¹ In fact, The World Health Organisation (WHO) estimates that over 100-million adults suffer from Obstructive Sleep Apnoea worldwide.²

It is also estimated that up to 80% of people with SDB are not diagnosed and, although you may be unaware of it happening, sleep apnoea will disturb your sleep and can lead to many symptoms including excessive daytime-sleepiness. Your partner may also hear the tell-tale signs of sleep apnoea while you sleep – usually snoring followed by a period of silence, and then perhaps a loud snort or a gasp as you resume breathing.

However, once recognised and diagnosed, sleep apnoea is easily treated with Positive Airway Pressure (PAP) therapy which can transform your quality of life and improve other related health-issues that arise from this condition.

The Phases of Obstructive Sleep Apnoea
Once you drift off to sleep, the soft tissue at the back of your throat relaxes and the lack of muscle tone and gravity then cause your airway to narrow resulting in vibration which produces snoring. If your airway continues to collapse, a breathing obstruction follows which causes an apnoea or hypopnea.

An apnoea is an event where your breathing stops completely for ten seconds or more. If your breathing is reduced (partial airway closure) but not stopped completely, it is called a hypopnea. In each case, the following event is the arousal or mini wake-up, when your brain notices the lack of oxygen and kick-starts your breathing process. This is often characterized by a snort or gasp which wakes you up just enough to regain control of your upper airway, breathe again, and then fall back to sleep. That is, until the next apnoea or hypopnea occurs to start the cycle off again!

The number of such events that occur per hour of sleep is measured on the Apnoea-Hypopnoea Index (AHI). People with severe sleep-apnoea can experience over 30 arousals per hour so it’s not a surprise they often feel exhausted during the day!

You may want to also read:

• What are the risks of Untreated Sleep Apnoea?
• Sleep Apnoea Symptoms
• Sleep Apnoea Treatment

¹ Morgenthaler TI, Kagramanov V, Hanak V, Decker PA. Complex sleep apnoea syndrome: is it a unique clinical syndrome? Sleep 2006;29(9):1203-9.
² Bousquet J, Khaltaev N. Global surveillance, prevention and control of Chronic Respiratory Diseases. A comprehensive approach. Global Alliance against Chronic Respiratory Diseases. World Health Organisation. 2007.