Obstructive Sleep Apnoea Syndrome

If you have obstructive sleep apnoea you have many periods when your breathing stops for 10 seconds or more when you sleep. You wake up briefly after each episode of stopped breathing to start breathing again. You do not usually remember the times you briefly wake up, but you have a disturbed night's sleep. As a result, you feel sleepy during the day. A typical person with this condition is overweight, male, and middle-aged, and snores loudly. However, it can affect anyone. Treatment usually works well.

What is obstructive sleep apnoea?

Obstructive sleep apnoea (OSA) is a condition where your breathing stops for short spells when you are asleep. The word apnoea means without breath - that is, the breathing stops. In the case of OSA, the breathing stops because of an obstruction to the flow of air down your airway. The obstruction to the airflow occurs in the throat at the top of the airway.

You may also have episodes where your breathing becomes abnormally slow and shallow. This is called hypopnoea. Because there can also be these episodes of hypopnoea, doctors sometimes use the term obstructive sleep apnoea/hypopnoea syndrome.

What happens in people with obstructive sleep apnoea?

When we sleep, the throat muscles relax and become floppy (like other muscles). In most people, this does not affect breathing. If you have OSA, the throat muscles become so relaxed and floppy during sleep that they cause a narrowing or even a complete blockage of the airway.

When your airway is narrowed and the airflow is restricted, at first this causes snoring. If there is a complete blockage then your breathing actually stops (apnoea) for around 10 seconds. Your blood oxygen level then goes down and this is detected by your brain. Your brain then tells you to wake up and you make an extra effort to breathe. Then, you start to breathe again with a few deep breaths. You will normally go back off to sleep again quickly and will not even be aware that you have woken up.

Sometimes, the airway can just partially collapse and can lead to hypopnoea. Breathing becomes abnormally slow and shallow. If this happens, the amount of oxygen that is taken into your body can be halved. Hypopnoea episodes also usually last for around 10 seconds.

If someone watches you, he or she will notice that you stop breathing for a short time, and then make a loud snore and a snort, perhaps even sound as if you are briefly choking, briefly wake up, and then get straight back off to sleep.

It is quite common for many of us to have the odd episode of apnoea when we are asleep, often finishing with a snort. This is of no concern. In fact, some people when they sleep have periods of 10-20 seconds when they do not breathe. However, people with OSA have many such episodes during the night. For the diagnosis of OSA, you need to have at least five episodes of apnoea, hypopnoea, or both events per hour of sleep. However, there are different levels of severity of OSA (mild, moderate or severe). People with severe OSA can have hundreds of episodes of apnoea each night. OSA is classified as:

  • Mild OSA - between 5-14 episodes an hour.
  • Moderate OSA - between 15-30 episodes an hour.
  • Severe OSA - more than 30 episodes an hour.

So, if you have OSA, you wake up many times during the night. You will not remember most of these times but your sleep will have been greatly disturbed. As a consequence, you will usually feel sleepy during the day. Daytime sleepiness in someone who is a loud snorer at night is the classic hallmark of someone who has OSA.

Who gets obstructive sleep apnoea?

OSA can occur at any age, including in children. However, it most commonly develops in middle-aged men who are overweight or obese. It is thought that as many as 3-7 in 100 middle-aged men and 2-5 in 100 middle-aged women develop OSA.

Factors that increase the risk of developing OSA, or can make it worse, include the following. They all increase the tendency of the narrowing in the throat at night to be worse than normal.

  • Overweight and obesity, particularly if you have a thick neck, as the extra fat in the neck can squash the airway.
  • Drinking alcohol in the evening. Alcohol relaxes muscles more than usual and makes the brain less responsive an apnoea episode. This may lead to more severe apnoea episodes in people who may otherwise have mild OSA.
  • Enlarged tonsils.
  • Taking sedative drugs such as sleeping tablets or tranquilisers.
  • Sleeping on your back rather than on your side.
  • Having a small or receding lower jaw (a jaw that is set back further than normal).
  • Smoking.

You may also have a family history of OSA.

What are the symptoms of obstructive sleep apnoea?

People with OSA may not be aware that they have this problem, as they do not usually remember the waking times at night. It is often a sleeping partner or a parent of a child with OSA that is concerned about the loud snoring and the recurring episodes of apnoea that they notice.

One or more of the following also commonly occur:

  • Daytime sleepiness. This is often different to just being tired. People with severe OSA may fall asleep during the day, with serious consequences. For example, when driving, especially on long monotonous journeys such as on a motorway. A particular concern is the increased frequency of car crashes involving drivers with OSA. Drivers with OSA have a 7-12 increased risk of having a car crash compared to average. You should not drive or operate machinery if you feel sleepy.
  • Poor concentration and mental functioning during the day. This can lead to problems at work.
  • Not feeling refreshed on waking.
  • Morning headaches.
  • Depression.
  • Being irritable during the day.

Some people with OSA find that they get up to pass urine frequently during the night. Less common symptoms also include night sweats and reduced sex drive.

People with untreated OSA also have an increased risk of developing high blood pressure. Having high blood pressure can increase your risk of having a heart attack or stroke. People with untreated OSA may also have an increased risk of developing problems with blood sugar regulation.

How is obstructive sleep apnoea diagnosed?

Epworth Sleepiness Scale

If you have daytime tiredness, sometimes a questionnaire is used to measure where you are on the Epworth Sleepiness Scale. This helps to gauge the level of sleepiness that you feel during the daytime. A high score indicates that you may have a sleeping disorder such as OSA.

Tests to confirm OSA

If you have symptoms that suggest OSA, or a high score on the Epworth Sleepiness Scale, your GP may refer you to a specialist for tests. There are various types of test that can be done whilst you sleep. The ones done may be determined by local policies and availability of equipment. For example:

  • By using a probe placed under your nose, your airflow may be measured whilst you sleep .
  • A sensor may record snoring volume and body movement whilst you sleep.
  • The oxygen level in your blood can be monitored by a probe clipped on to your finger.
  • Breathing can be monitored and recorded by the use of special belts placed around the chest and abdomen.
  • A video of you sleeping may be helpful.

You may be asked to spend a night in hospital for the tests to be done. However, some of the tests may be done in your own home from equipment supplied by the specialist. The information gained from the tests can help a specialist to firmly diagnose or rule out OSA.

You doctor will usually check your blood pressure. (OSA is associated with high blood pressure.) They may also suggest other tests to exclude other causes of your sleepiness. For example, a blood test can check for an underactive thyroid gland.

Obstructive sleep apnoea - driving and operating machinery

If you have OSA and you are a driver, you must not drive and you must inform the Driver and Vehicle Licensing Agency (DVLA). For normal car drivers, you will usually be allowed to resume driving after you have had treatment so that you no longer have daytime sleepiness. However, special rules apply if you have an LGV or similar licence.

Equally, if you have daytime sleepiness, you should not operate heavy machinery, as this can also be dangerous.

What is the treatment for obstructive sleep apnoea?

General measures

Things that can make a big difference include:

  • Losing some weight if you are overweight or obese.
  • Not drinking alcohol for 4-6 hours before going to bed.
  • Not using sedative drugs.
  • Stopping smoking if you are a smoker.
  • Sleeping on your side or in a semi-propped position.

Continuous positive airway pressure (CPAP)

This is the most effective treatment for moderate or severe OSA. It may be used to treat mild OSA if other treatments are not successful. This treatment involves wearing a mask when you sleep. A quiet electrical pump is connected to the mask to pump room air into your nose at a slight pressure. The slightly increased air pressure keeps the throat open when you are breathing at night and so prevents the blockage of airflow. The improvement with this treatment is often very good, if not dramatic.

If CPAP works, (as it does in most cases) then there is an immediate improvement in sleep. Also, there is an improvement in daytime well-being, as daytime sleepiness is abolished the next day. Snoring is also reduced or stopped. The device may be cumbersome to wear at night, but the benefits are usually well worth it. Comments like "I haven't slept as well for years" have been reported from some people after starting treatment with CPAP.

Lifelong treatment is needed. Sometimes you can have problems with throat irritation or dryness or bleeding inside you nose. However, newer CPAP machines tend to have a humidifier fitted which helps to reduce these problems.

Mandibular advancement devices

The mandible is the lower jaw. There are devices that you can wear inside your mouth when you sleep. They work by pulling the mandible forward a little so that your throat may not narrow as much in the night. These devices look a bit like gum shields that sports-people wear. Although you can buy these devices without a prescription, it is best to get one properly fitted by a dentist if one is recommended. These devices can work well in some cases. They tend to be used in mild OSA or in people who are unable to tolerate CPAP treatment.  However, the evidence to support their effectiveness is very limited.


Surgery is not often used to treat OSA in adults. However, sometimes an operation may be helpful to increase the airflow into your airway. For example, if you have large tonsils or adenoids, it may help if these are removed. This is more commonly done in children with OSAS. If you have any nasal blockages, an operation may help to clear the blockage.