Obstructive sleep apnoea (OSA) is a condition where the walls of the throat relax and narrow during sleep, interrupting normal breathing.
There are two types of breathing interruption characteristic of OSA:
- apnoea – where the muscles and soft tissues in the throat relax and collapse sufficiently to cause a total blockage of the airway; it is called an apnoea when the airflow is blocked for 10 seconds or more
- hypopnoea – a partial blockage of the airway that results in an airflow reduction of greater than 50% for 10 seconds or more
As many people with OSA experience episodes of both apnoea and hypopnoea, doctors sometimes refer to the condition as obstructive sleep apnoea-hypopnoea syndrome, or OSAHS.
The term "obstructive" distinguishes OSA from rarer forms of sleep apnoea, such as central sleep apnoea, which is caused by the brain not sending signals to the breathing muscles during sleep.
What happens in OSA?
People with OSA may experience repeated episodes of apnoea and hypopnoea throughout the night.
During an episode, the lack of oxygen triggers your brain to pull you out of deep sleep – either to a lighter sleep or to wakefulness – so your airway reopens and you can breathe normally.
After falling back into deep sleep, further episodes of apnoea and hypopnoea can occur. These events may occur around once every one or two minutes throughout the night in severe cases.
Most people with OSA snore loudly. Their breathing may be noisy and laboured, and it is often interrupted by gasping and snorting with each episode of apnoea.
These repeated sleep interruptions can make you feel very tired during the day. You'll usually have no memory of your interrupted breathing, so you may be unaware you have a problem unless a partner, friend or family member notices the symptoms while you sleep.
Read more about the symptoms of OSA.
When to seek medical advice
You should see your GP if you think you might have OSA.
They can check for other possible reasons for your symptoms and can arrange for an assessment of your sleep to be carried out through a local sleep centre.
Read more about diagnosing OSA.
What causes OSA?
It's normal for the muscles and soft tissues in the throat to relax and collapse to some degree while sleeping.
For most people this doesn't cause breathing problems, but in people with OSA the airway has narrowed as the result of a number of factors, including:
- being overweight or obese
- having a large neck
- taking medicines that have a sedative effect, such as sleeping tablets
- having an unusual structure in the neck, such as an narrow airway, large tonsils, adenoids or tongue, or a small lower jaw
- smoking or drinking alcohol, particularly before going to sleep
Read more about the causes of OSA.
Who is affected?
OSA is a relatively common condition that affects more men than women.
Most cases of OSA develop in people aged 30 to 60 years old, although it can affect people of all ages, including children.
In the UK, it is estimated around 4% of middle-aged men and 2% of middle-aged women have OSA.
As someone with OSA may not notice they have the condition themselves, it is likely that OSA often goes undiagnosed.
How OSA is treated
OSA is a treatable condition, and there are a variety of treatment options that can reduce the symptoms.
Treatment options for OSA include:
- lifestyle changes – such as losing excess weight, cutting down on alcohol and sleeping on your side
- using a continuous positive airway pressure (CPAP) device – these devices prevent your airway closing while you sleep by delivering a continuous supply of compressed air through a mask
- wearing a mandibular advancement device (MAD) – this gum shield-like device fits around your teeth, holding your jaw and tongue forward to increase the space at the back of your throat while you sleep
Surgery may also be an option if OSA is thought to be the result of a physical problem that can be corrected surgically, such as an unusual inner neck structure.
However, for most people surgery is not appropriate and may only be considered as a last resort if other treatments have not helped.
Read more about treating OSA.
The treatments mentioned above can often help control the symptoms of OSA, although treatment will need to be lifelong in most cases.
If OSA is left untreated, it can have a significant impact on your quality of life, causing problems such as poor performance at work and school, and placing a strain on your relationships with others.
Poorly controlled OSA can also increase your risk of developing high blood pressure, having a serious accident caused by tiredness (such as a car crash), having a stroke or heart attack, and developing an irregular heartbeat (such as atrial fibrillation).
Read more about the complications of OSA.
Can OSA be prevented?
It is not always possible to prevent OSA, but making certain lifestyle changes may reduce your risk of developing the condition. These include:
- losing weight if you are overweight or obese
- limiting your alcohol consumption and avoiding alcohol during the evening
- stopping smoking if you smoke
- avoiding the use of sleeping tablets and tranquillisers