Encyclopaedia


Sleep apnoea

Introduction

Obstructive sleep apnoea (OSA) is a condition that causes interrupted breathing during sleep. For people with OSA, two types of breathing interruptions have been defined:

  • 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 air flow reduction of greater than 50% for 10 seconds or more

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.

Sleep

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 (see below).

What happens during OSA?

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

The 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.

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.

How common is OSA?

OSA is a relatively common condition that affects men more than women. In the UK, it is estimated that around 4 in 100 middle-aged men and 2 in 100 middle-aged women have OSA.

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. Only one in four people with obstructive sleep apnoea are diagnosed with the condition.
 
Studies have also shown that 60% of people over 65 years old have OSA.

Outlook

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

Stages of sleep

Sleep can be divided into two categories:

  • rapid eye movement (REM) sleep usually occurs around 90 minutes after falling asleep; during REM sleep, brain activity increases and dreaming occurs; a number of periods of REM can occur during a night’s sleep (usually three to five episodes)
  • non-rapid eye movement (NREM) sleep is made up of four different stages (see below); one sleep cycle may consist of several stages of NREM sleep followed by a period of REM sleep.

There are four different stages of NREM sleep.

  • Stage 1 (drowsiness) may last 5 to 10 minutes, during which time your muscles relax and you may be easily disturbed. You may also feel as if you are falling, which causes a muscle contraction known as hypnic myoclonia or ‘sleep jerks’.
  • Stage 2 (light sleep): eye movements stop during this stage, your heart rate slows down and your body temperature decreases as your body prepares itself for deep sleep.
  • Stages 3 and 4 (deep sleep): these two stages are deep sleep. Stage 4 is more intense than stage 3. During these stages, your physical energy levels are restored and your immune system is strengthened. If woken, you may feel disorientated for a few minutes. Around 90 minutes into this sleep cycle you will begin to have REM sleep.
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Symptoms

Most people with obstructive sleep apnoea (OSA) snore loudly. Their partners may notice that their breathing is laboured and noisy, and it can often be interrupted by gasping and snorting as they experience an episode of apnoea.

If you have OSA, you may have no memory of your sleep being interrupted, but you will wake feeling that you have not had a decent night's sleep.

Over time, the repeated interruptions to your sleep will lead to the symptoms of sleep deprivation. These 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 short temper,
  • depression,
  • anxiety,
  • lack of interest in sex, and
  • in men, impotence (inability to get, or maintain, an erection).

Some people with OSA may also find that they wake up frequently during the night in order to urinate.

Driving

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 the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that could have an impact on your driving ability. The Directgov website has advice about how to tell the DVLA about a medical condition.

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Causes

Obstructive sleep apnoea (OSA) is caused by the muscles 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 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 can be reopened, and you can breathe normally.

Known risk factors for OSA

The known risk factors for OSA are outlined below.

  • Being overweight is a major risk factor because 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 over - 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 a sleeping pills, or tranquillisers,
  • Having an unusual inner-neck structure - such as an unusually narrow airway, or unusually large tonsils, or tongue, or having a lower jaw that is set back further than normal.
  • 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.

 

 

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Diagnosis

If you are experiencing the symptoms of excessive daytime sleepiness, such as feeling drowsy, a lack of energy and poor memory, a useful first step may be to ask a partner, friend, or relative to observe you when you are asleep. They may be able to spot episodes of breathlessness that could help to confirm a diagnosis of obstructive sleep apnoea (OSA).

Physical examination and tests

You should then see your GP who will ask you about your symptoms, such as whether you regularly fall asleep during the day against your will.

Your GP will also carry out a physical examination, and a number of tests, including a blood pressure test. A blood test is also likely to be arranged. The examination and tests are carried out in order to rule out other conditions that could explain your tiredness, such as an under-active thyroid gland (hypothyroidism).

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.

Polysomnography

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. 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.

During the testing process, specialist sleep nurses will monitor the signals. 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.

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 downloaded onto a computer and 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.

 

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Treatment

Lifestyle changes

Some cases of mild to moderate OSA can be successfully treated by making changes to your lifestyle. These include:

  • losing weight, if you are obese,
  • avoiding alcohol during the evening,
  • quitting smoking, if you are a smoker, and
  • avoiding the use of sleeping tablets and tranquillisers.

Sleeping on your side, rather than on your back, may also help to relieve symptoms of OSA.

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 at night 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, nose bleeds 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 cardiac (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.

Treating sleep apnoea 

The didgeridoo

As unusual as it may sound, there is evidence to suggest that regularly playing the Australian wind instrument, the didgeridoo, can help to reduce the symptoms of mild to moderate OSA.

A study found that people who attended regular didgeridoo lessons and practised every day for four months felt significantly less daytime sleepiness.

This may be because regularly playing the didgeridoo strengthens the muscles in the upper airways.

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

The recommended daily amount of alcohol consumption is 3-4 units a day for men and 2-3 units a day for women. 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.
   
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.

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 at night 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, nose bleeds 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 cardiac (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.
 
A 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.
 
A MRS can be made for you by an orthodontist (a dental specialist) using impressions of your teeth and jaw. A MRS is available on the NHS. It has a life span of about 18 months before it needs to be replaced.

If you have a 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 a MRS.

Stimulants

If your symptoms of daytime sleepiness are particularly severe, you may be given a short-term dose of a medicine known as a stimulant. Stimulants work by increasing the activity of your nervous system to make you feel more alert and awake.

If you are having severe symptoms of sleepiness during the daytime, a medicine called modafanil may be recommended. Although it is usually effective, modafanil can cause a number of common side effects, such as:

  • nervousness
  • irregular heart beats (palpitations)
  • chest pain
  • headache
  • dizziness
  • dry mouth
  • nausea
  • stomach pain
  • indigestion
  • diarrhoea
  • constipation
  • difficulty sleeping and tiredness
  • pins and needles
  • blurred vision

Speak to your GP if you have any of these side effects while you are taking a stimulant medicine. They may be able to prescribe an alternative medicine for you.

Do not take modafanil if you are pregnant or breastfeeding because it is not known whether this treatment can harm you or your baby.

Do not drive or operate heavy machinery if you are having severe symptoms of daytime sleepiness. The side effects listed above will further affect your ability and judgement.

In rare situations, modafanil can cause depression and encourage people to have suicidal thoughts. If this happens, stop taking the medicine and visit your GP.

The long-term use of stimulants is not recommended because they can become addictive. They are also not recommended for women who are pregnant or breastfeeding.

Surgery

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), which 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 (the area of your body being operated on is numbed so that you do not feel any pain). You will, however, remain awake during the procedure).
 
The National Institute of Health and Clinical Excellence (NICE) have said that soft-palate implants are safe, but they are not recommended for treating OSA because there is a lack of evidence about their effectiveness. However, in exceptional cases, this form of treatment is recommended for treating snoring that is associated with sleep apnoea.

 

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Complications

High blood pressure

Many people with obstructive sleep apnoea (OSA) develop high blood pressure (hypertension). This also increases your risk of developing a cardiovascular disease (conditions affecting the heart and blood circulation), such as a stroke, or heart attack.

It is currently uncertain whether hypertension is a direct response to OSA, or whether it is a 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 to prevent hypertension.

See the A-Z topic about High blood pressure for more information about this condition.

Other medical conditions

If OSA is left untreated, hypertension also 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.

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.

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