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Obstructive sleep apnoea

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What is obstructive sleep apnoea?

Obstructive sleep apnoea (OSA) is a condition that causes interrupted breathing during sleep.

There are two types of breathing interruption characteristic of OSA:

  • apnoea – 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

Sleep apnoea is associated with being overweight, and other risk factors. Read more about the causes of sleep apnoea.

Because of the episodes of hypopnoea that occur during OSA, doctors sometimes refer to the condition as 'obstructive sleep apnoea-hypopnoea syndrome'.

The term 'obstructive' distinguishes OSA from rarer forms of sleep apnoea, such as central sleep apnoea, which is caused by the brain 'forgetting' to breathe during sleep.

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Sleep is driven by natural brain activity. You need to have a certain amount of deep sleep for your body and mind to be fully refreshed. Having only limited episodes of deep sleep will leave you feeling very tired the next day.

In order to function properly, most adults need seven to eight hours of sleep. Around 15-25% of that time should be spent in the deepest phase of sleep, known as slow-wave sleep.

What happens during OSA?

During the night, people with OSA may experience repeated episodes of apnoea and hypopnoea.

During an episode, lack of oxygen causes the person to come out of deep sleep and into a lighter state of sleep, or a brief period of wakefulness, in order to restore normal breathing. However, after falling back into deep sleep, further episodes of apnoea and hypopnoea can occur. Such events may occur more than once a minute throughout the night.

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.

The repeated interruptions to sleep caused by OSA can make the person feel very tired during the day. A person with OSA will usually have no memory of breathlessness, so they are often unaware that they are not getting a proper night's sleep.

Read more about the symptoms of sleep apnoea.

How common is OSA?

OSA is a relatively common condition that affects more men than women.

The onset of OSA is most common in people aged 35 to 54 years old, although it can affect people of all ages, including children. The condition often goes undiagnosed. It is estimated that up to 5% of adults have undiagnosed OSA.

Studies have also shown that 60% of people over 65 years old have OSA.


OSA is a treatable condition and there are a variety of treatment options to reduce the symptoms.

Lifestyle changes, such as losing excess weight, can often help mild cases of sleep apnoea to resolve. In more severe cases, the use of breathing apparatus while sleeping may be necessary.

Read more about how sleep apnoea is treated.

Left untreated, OSA can increase the risk of:

  • high blood pressure (hypertension)
  • heart attack
  • stroke
  • obesity
  • type 2 diabetes

Untreated OSA also increases a person’s risk of developing heart failure and irregular heartbeats, and it can lead to poor performance at work and at school.

Read more about the complications of sleep apnoea.

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Symptoms of obstructive sleep apnoea

Episodes of interrupted breathing are often visible in someone with obstructive sleep apnoea (OSA) who is asleep. OSA can also cause other symptoms, often due to tiredness resulting from lack of deep sleep.

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.

If you have OSA, you may have no memory of your interrupted breathing during the night. However, when you wake up you are likely to feel as though you have not had a good night's sleep.

Other symptoms of OSA include:

  • feeling very sleepy during the day
  • waking up with a sore or dry throat
  • poor memory and concentration
  • headaches (particularly in the morning)
  • irritability and a short temper
  • anxiety
  • depression
  • lack of interest in sex
  • in men, impotence (inability to get or maintain an erection)

Some people with OSA may also wake up frequently during the night to urinate.


As someone with OSA can suffer a lack of refreshing sleep, they run an increased risk of being involved in a life-threatening accident, such as a car crash. Their risk of having a work-related accident also increases.

Research has shown that someone who has been deprived of sleep due to OSA has the same impaired judgement and reaction time as someone who is over the drink-drive limit.

If you have OSA, it could affect your ability to drive. It is your legal obligation to inform your driving licence issuer about a medical condition that could have an impact on your driving ability.

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Obstructive sleep apnoea causes

Obstructive sleep apnoea (OSA) is caused by the muscles and soft tissue in the back of your throat collapsing inwards during sleep.

These muscles support your tongue, tonsils and soft palate (a muscle at the back of the throat that is used in speech).

Once the muscles relax, the airway in your throat can narrow or become totally blocked. This interrupts the oxygen supply to your body, which triggers your brain to pull you out of deep sleep so that your airway reopens and you can breathe normally.

Risk factors

There are a number of risk factors for OSA, described below.

  • Being overweight – excessive body fat increases the bulk of soft tissue in the neck, which can place a strain on the throat muscles; excess stomach fat can also lead to breathing difficulties, which can make OSA worse
  • Being male – it is not known why OSA is more common in men than in women, but it may be related to different patterns of body fat distribution
  • Being 40 years of age or more – although OSA can occur at any age, it is more common in people who are over 40 years old
  • Having a large neck – a man of average height (1.7m or 5ft 8in) with a collar size that is greater than 45cm (18 inches) is classed as obese and has an increased risk of developing OSA
  • Taking medicines that have a sedative effect, such as sleeping tablets or tranquillisers
  • Having an unusual inner-neck structure – an unusually narrow airway, unusually large tonsils or tongue, or a small lower jaw can push the tongue backwards
  • Having excess folds in the inner lining of the mouth
  • Alcohol – drinking alcohol can make snoring and sleep apnoea worse
  • Smoking – you are three times more likely to develop sleep apnoea if you smoke
  • Being menopausal – the changes in hormone levels during the menopause may cause the throat muscles to relax
  • Having a family history of OSA – there may be genes inherited from your parents that can make you more susceptible to OSA
  • Diabetes – OSA is three times more common in people with diabetes
  • Nasal congestion – OSA occurs twice as often in people with nasal congestion, which may be due to the airways being narrowed

[AD] Got questions about sleep apnoea? Talk to a doctor online to help you get answers.

Diagnosing obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is diagnosed by observation of your sleep.

If you have symptoms of excessive daytime sleepiness, such as feeling drowsy, a lack of energy and poor memory, ask a partner, friend or relative to observe you while you are asleep. If you have OSA, they may be able to spot episodes of breathlessness.

If you think you have OSA, visit your doctor.

Physical examination and tests

Your doctor will ask you a number of questions about your symptoms, such as whether you regularly fall asleep during the day against your will.

Your doctor will also carry out a physical examination and some tests, including a blood pressure test. A blood test is also likely to be arranged.

A physical examination and tests are carried out to rule out other conditions that could explain your tiredness, such as hypothyroidism (an underactive thyroid gland).

The next step is to observe you while you are asleep. To do this, you may be asked to spend a night at a sleep centre so that any events that indicate OSA can be monitored. This is known as polysomnography (see below).

Alternatively, you may be given a monitoring device to wear at night while you sleep at home (a home sleep study). The device is returned to the sleep centre the following day so that the recorded information can be downloaded by staff.

Testing at a sleep centre

Sleep centres are specialist clinics or hospital departments that help treat people with sleep disorders.

Typically you will be referred for an overnight stay in a sleep centre, during which your sleep will be observed.


The main investigation into your sleep is polysomnography. This investigation will enable sleep specialists to decide what is the best treatment for you.

During polysomnography, specialist nurses will place a series of electrodes on the surface of your skin (this is painless) and bands on other areas.

You will then be provided with a room in which you can sleep for the night. While you sleep, specialist sleep nurses will monitor the signals from the electrodes.

Electrodes and bands are placed on the following areas:

  • electrodes on your face and scalp
  • electrodes above your lip
  • bands around your chest
  • bands around your abdomen (tummy)

Sensors will also be placed on your legs, and an oxygen sensor will be attached to your finger.

The tests that are carried out during a polysomnography include:

  • electro-encephalography (EEG) – this monitors your brain waves
  • electromyography (EMG) – this monitors your muscle tone
  • recording thoracoabdominal movements (movements in your chest and abdomen)
  • recording oronasal airflow (the airflow in your mouth and nose)
  • pulse oximetry – this measures your heart rate and blood oxygen levels
  • electrocardiography (ECG) – this monitors your heart
  • sound and video recording to record your breathing and snoring, and your behaviour during the night

Polysomnography must be done by experienced technicians in a hospital or sleep centre.

If OSA is diagnosed during the early part of the night, you may be given continuous positive airway pressure (CPAP) treatment. CPAP involves using a mask that delivers constant compressed air to the airway and stops the airway from closing, which prevents OSA.

Read how sleep apnoea is treated for more information about CPAP treatment.

Once the tests have been completed, staff at the sleep centre should have a good idea about whether or not you have OSA. If you do, they can determine how much it is interrupting your sleep and recommend appropriate treatment.

Apnoea-hypopnoea index (AHI)

The severity of OSA is determined by how many episodes of apnoea and hypopnoea you experience over the course of an hour. These episodes are measured using the apnoea-hypopnoea index (AHI).

The severity of OSA is measured using the following criteria:

  • mild – an AHI reading of 5 to 14 episodes an hour
  • moderate – an AHI reading of 15 to 30 episodes an hour
  • severe – an AHI reading of more than 30 episodes an hour

An AHI reading of less than 10 is unlikely to be linked to a clinical problem or sleep disorder.

Home study

A home sleep study is a possible option. However, you will still need to visit a specialist sleep centre during the day to learn how to use the home study equipment.

You will need to learn how to use portable recording equipment, which includes:

  • a breathing sensor
  • sensors to monitor your heart rate
  • oxygen sensors that are put around your finger and bands around your chest

The equipment records levels of oxygen, breathing movements, heart rate and snoring.

After you have used this equipment overnight, you will need to take it to the sleep centre, where the information will be analysed by sleep specialists.

If more information about sleep quality is required by the sleep centre, a polysomnography will be required, which will be carried out at the sleep centre.

[AD] Got questions about sleep apnoea? Talk to a doctor online to help you get answers.

Treating obstructive sleep apnoea

Common treatments for obstructive sleep apnoea (OSA) include advice on lifestyle changes, and use of breathing apparatus while you are asleep.

Lifestyle changes

Mild cases of obstructive sleep apnoea (OSA) can usually be treated by making lifestyle changes, such as:

  • losing weight (if you are overweight or obese)
  • stopping smoking (if you smoke)
  • limiting your alcohol consumption

Men should not regularly drink more than 3 to 4 units of alcohol a day. Women should not regularly drink more than 2 to 3 units of alcohol a day. If you've had a heavy drinking session, avoid alcohol for 48 hours.

'Regularly' means drinking these amounts every day or most days of the week.

One unit of alcohol is equal to half a pint of normal-strength beer, a small glass of wine or a pub measure (25ml) of spirits.

Stopping smoking can also help sleep apnoea to resolve. See quitting smoking for more information, support and advice about giving up smoking.

Sleeping on your side, rather than on your back, may also help to relieve the symptoms of OSA, although it will not prevent the condition.

See prevention of sleep apnoea for more information about lifestyle changes that can help prevent sleep apnoea.

Continuous positive airway pressure (CPAP)

Moderate to severe cases of sleep apnoea may need to be treated using a type of treatment called continuous positive airway pressure (CPAP). This involves using breathing apparatus to assist with your breathing while you are asleep.

CPAP is used when you are asleep. A mask is placed over your nose, which delivers a continuous supply of compressed air. The compressed air prevents the airway in your throat from closing.

Earlier versions of CPAP often caused nasal dryness, nosebleeds and a sore throat. However, the latest version includes a humidifier (a device that increases moisture), which helps to reduce these side effects.

If CPAP causes you discomfort, inform your treatment staff because the device can be modified to make it more comfortable. For example, you can try using a CPAP machine that starts with a low air pressure and gradually builds up to a higher air pressure as you fall asleep.

As CPAP can feel peculiar to start with, you may be tempted to abandon the treatment. However, people who persevere with it quickly get used to wearing the mask, and their symptoms improve significantly.

CPAP is available on the NHS and it is the most effective therapy for treating severe cases of OSA. It reduces blood pressure and the risk of stroke by 40%, and lowers the risk of heart complications by 20%.

Possible side effects of CPAP include:

  • mask discomfort
  • nasal congestion, runny nose or irritation
  • difficulty breathing through your nose
  • headaches and ear pain
  • stomach pain and flatulence (wind)

If you have any of these side effects, discuss them with your sleep specialist who may be able to recommend an alternative treatment.

Mandibular responding splint (MRS)

A mandibular responding splint (MRS) is sometimes referred to as a mandibular advancement device or MAD. It is a dental appliance, similar to a gum shield, and is used to treat mild sleep apnoea. It is not recommended for more severe sleep apnoea.

An MRS is worn over your teeth when you are asleep. It is designed to hold your jaw and tongue forward to increase the space at the back of your throat and reduce the narrowing of your airway that causes snoring.

‘Off-the-shelf’ MSRs are available from specialist websites, but most experts do not recommend them, as poor-fitting MRSs can make symptoms worse. It is recommended that you have a MRS made for you by a dentist with training and experience in treating sleep apnoea.

If you have an MRS, avoid using hot water to clean it because this will damage it. Use cold water and a soft brush. A MRS may not be suitable treatment for you if you do not have many (or any) teeth. If you have dental caps, crowns or bridgework, consult your dentist to ensure that they will not be unduly stressed or damaged by an MRS.


Surgery to treat OSA is usually not recommended because evidence shows that it is not as effective as CPAP in controlling the symptoms.

Therefore, surgery for OSA is usually considered as a last resort when all other treatment options have failed and if OSA is severely affecting your quality of life.

Surgery may be considered to correct sleep apnoea if you have any of the following:

  • deviated nasal septum – this is where the tissue in the nose that divides the two nostrils is bent to one side, often as a result of a sports injury
  • enlarged tonsils – which can obstruct the airway
  • small lower jaw – a small lower jaw with an overbite (when the upper teeth overlap over the lower teeth) can make the throat narrow

A range of surgical treatments can be used to treat OSA. These include:

  • Tracheostomy – a tube is inserted directly into your neck to allow you to breathe freely, even if the airways in your upper throat are blocked.
  • Uvulopalatopharyngoplasty – this involves removing excess tissue in the throat to widen your airway. It is the most common type of surgery for treating sleep apnoea in adults. Some patients with particular anatomical abnormalities may benefit from this type of surgery.
  • Tonsillectomy – the tonsils are removed if they are enlarged and blocking your airway when you sleep.
  • Adenoidectomy the adenoids (small lumps of tissue that are located at the back of the throat, above the tonsils) in children are removed if they are enlarged and are blocking the airway during sleep. This is often the first treatment for children with sleep apnoea as enlarged adenoids and tonsils are the main cause of sleep apnoea in children.
  • Bariatric surgery – this is for weight loss. It involves removing part of the stomach or using a device to reduce the size of the stomach. You may consider this type of surgery if you are severely obese (if you have a body mass index of 40 or more) and it is making your sleep apnoea worse.

Soft-palate implants

Soft-palate implants make the soft palate (part of the roof of the mouth) stiffer and less likely to vibrate and cause an obstruction. The implants are thin and are inserted into the soft palate under local anaesthetic.

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Obstructive sleep apnoea is associated with high blood pressure.

High blood pressure, in turn, can raise your risk of a range of other health conditions.

High blood pressure

Many people with obstructive sleep apnoea (OSA) develop high blood pressure (hypertension).

If you have high blood pressure, your risk of developing cardiovascular diseases, such as a heart attack or stroke, is also increased.

Currently, it is uncertain whether people develop hypertension as a direct response to OSA, or whether it is the result of an underlying cause of OSA, such as obesity. However, maintaining a healthy weight, taking regular exercise and eating a healthy, balanced diet is the best way of preventing hypertension.

Read about high blood pressure.

Other medical conditions

If OSA is left untreated, hypertension increases your risk of developing other serious conditions, including:

  • heart attack – a serious condition that is caused by a blood clot blocking the supply of blood to the heart
  • stroke – a serious medical condition that is caused by a disturbance in the blood supply to the brain
  • obesity – a condition in which a person is carrying too much body fat for their height and sex
  • type 2 diabetes – a long-term condition that is caused by too much sugar (glucose) in the blood


You can reduce your risk of obstructive sleep apnoea (OSA) by making a few key lifestyle changes.

Lifestyle changes

Lifestyle changes that reduce the risk of OSA include:

  • losing weight if you are overweight or obese
  • limiting your alcohol consumption and avoiding alcohol during the evening
  • quitting smoking if you smoke
  • avoiding the use of sleeping tablets and tranquillisers
  • not sleeping on your back because this can make snoring worse

Improving overall sleep quality

Other changes you can make to improve the quality of your sleep include:

  • reducing the amount of light and noise in your bedroom
  • not reading or watching television in bed
  • keeping work-related activities outside of the bedroom
  • relaxing before going to bed

Read more about insomnia.

Terry's story

Terry Gasking was diagnosed with sleep apnoea after a couple of terrifying incidents during which he fell asleep at the wheel. He tells us how he got through it.

“I was driving along the A418 when I suddenly woke up and found myself going down the wrong side of the road. I must have fallen asleep at the wheel, even though I didn’t feel particularly tired. Thankfully, nothing was coming the other way, or I wouldn’t be here today.

“The second time was particularly frightening. I was driving past a village school and remember being fully alert, watching the children to make sure they didn’t step into the road. The next moment, I was gone: I’d fallen asleep, completely unaware. I woke up 50 yards away, about four feet from a brick wall. I could have killed a child.

“The worst thing about snoring and sleep apnoea is that you have no idea that it’s happening to you. You think you’re sleeping for hours, but you’re not – you’re only sleeping for very short spells. In my case, I was diagnosed as a moderate sufferer: I stopped breathing 28 times an hour. This means my average sleep period was just two minutes.

“When you think sleep deprivation is a form of torture, you realise that people with sleep apnoea go through torture every night because they’re not getting enough sleep.

“I tried every simple ‘remedy’ I could lay my hands on – nose clips, things to put up your nose. Nothing worked. Then I tried CPAP (continuous positive airway pressure). The sleep deprivation that I’d suffered for 30 years went overnight. Suddenly, I was given the energy I had 20 years ago.”

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