Obstructive Sleep Apnoea

Apnoea means ‘no breath’.

Obstructive Sleep Apnoea (OSA) occurs when there is no flow of air into or out of the lungs during sleep because of blockage or obstruction to the upper airway. This obstruction can occur many times through the night.

During sleep, the body muscles relax, including the muscles holding the upper airway open. This leads to partial closure of the airway on breathing in, even in normal people. In some people, this narrowing is more pronounced, leading to snoring.


Further narrowing of the airway can occur, leading to complete closure – this is obstructive sleep apnoea. During the period of apnoea, oxygen levels in the blood fall. The body responds to this obstruction by arousing just enough to re-open the airway. These arousals are usually too short to be remembered, but do disrupt sleep and can occur many hundreds of times through the night.

The pattern of breathing an observer would hear would be increasingly loud snoring followed by silence, ending in a loud gasp. These arousals may be so marked that the sufferer may be seen to move, jerk, or turn over without seeming to be aware of this. This sleep disruption can lead to excessive daytime sleepiness.

Daytime symptoms can include:

  • Excessive sleepiness
  • Lack of concentration
  • Poor memory
  • Early morning headaches
  • Sexual dysfunction
  • Reduced quality of life

Night time symptoms can include:

  • Loud snoring with episodes of stopping breathing,
  • Gasps, grunts
  • Choking episodes
  • Struggling to breathe
  • Frequent urination

What causes OSA?

The commonest cause is being overweight, but in some people there may be a narrow airway. In children, OSA can be caused by large tonsils. However, in some people there may be no obvious cause. It becomes more common in middle age.

How common is OSA?

This is a common condition. It is more common in men than women and can affect up to 10% of the population to some extent. It may be aggravated/caused by alcohol, sedatives and certain other medical conditions.

Why is OSA an important condition?

Repetitive arousals disturbing sleep can lead to excessive daytime sleepiness, increasing the risk of driving accidents and work related accidents which can result in death or serious injury to self or others.

The falls in oxygen levels in the blood associated with the periods of apnoea can lead to raised blood pressure, heart disease and strokes over a period of time.

Mental changes can also occur.


In some mild cases simple measures such as weight loss, avoidance of alcohol and avoidance of sedatives can be tried first, with good regular sleep habits.

Mandibular advancement devices may have a role in some patients with mild/moderate OSA.

Avoiding sleeping on your back can sometimes reduce or control your OSA.

However, the first treatment of choice in Moderate and Severe OSA is CPAP. (CPAP stands for Continuous Positive Airway Pressure). CPAP works by blowing air at slightly higher pressure than atmosphere through a mask (via the nose or nose and mouth) into the upper airway to hold the airway open, preventing partial or full collapse and obstruction to breathing.

CPAP is a treatment not a cure (see CPAP leaflet).

It is rare for surgery to be of any benefit in severe OSA.

OSA and driving

If you are excessively sleepy you should not drive or operate dangerous machinery (see DVLA website for current regulations (www.dvla.gov.uk.)


You should inform your doctor or other medical attendants/nurses that you have OSA, especially if an operation is likely to be necessary for any reason.

Download our OSA leaflet (220kb)
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