Sleep Apnea - Causes Symptoms & Diagnosis

Author: CPAP Club  Date Posted:5 June 2019 

What is Sleep Apnea

Sleep APNOEA is a temporary suspension of breathing which occurs repeatedly during sleep. It often affects overweight people or thosehaving an obstruction in the breathing tract, an abnormally small throat opening, or a neurological disorder. 

Obstructive Sleep Apnoea-Hypopnoea Syndrome (OSAHS) is a sleep disorder in which a person has irregular breathing at night and is excessively sleepy during the day. 

In sleep apnoea, the upper airway (pharynx) collapses repeatedly, at irregular intervals, during sleep. Apnoea is when the airway collapses and is blocked completely, cutting off the flow of air. Hypopnoea occurs when the collapse is only partial. The airway is reduced and the person will experience hypoventilation (inadequate breathing). 

The pause in breathing, or period of very restricted breathing, is usually defined as about 10 seconds, although it varies from person to person. The frequency of apnoea or hypopnoea is used to assess the severity of this condition. The number of times that the apnoea occurs in an hour is called the apnoea/hypopnoea index (AHI) or the respiratory disturbance index (RDI). An AHI of between 5 and 14 in an hour is mild sleep apnoea. Between 15 and 30 is moderate. More than 30 in an hour is severe – that means at least one every two minutes. 

As people with sleep apnoea fall asleep, the muscles in their airway relax. The collapsing of the airway (pharynx) causes people to come out of deep sleep and either wake momentarily or sleep lightly, as they are trying to breathe more deeply. The person soon resumes deep sleep, and the cycle begins again. The period of wakefulness is so brief that even though it may happen hundreds of times a night, the person usually won’t remember waking up. 

Sleep apnoea affects around one in 100 people. Overweight men between the ages of 30 and 65 are most commonly affected, but it may also occur in children with enlarged tonsils or adenoids.

Sleep Apnea Causes

Sleep apnoea is caused by factors that make the throat narrow more than usual during sleep. If the throat is narrower to start with, for example because the tonsils are enlarged, it is easier for the throat muscles to close and block the airway. Other causes of a narrowed throat include: 

  • set-back lower jaw; 
  • partially blocked nose, for example caused by rhinitis (inflammation of the nose lining) or nasal polyps (benign growths, often occurring as a result of allergic conditions such as hayfever); 
  • being overweight, particularly with a short thick neck (fat in the neck squashes the throat from outside); 
  • enlarged adenoids or tonsils;  
  • physiological features inside the mouth, such as a particularly large tongue or small opening to the pharynx; 
  • excessive alcohol, sedative drugs or strong painkillers. 

Men and older people are more likely to experience sleep apnoea. 

Sleep Apnea Symptoms

People affected by Sleep Apnoea are often unaware that they have the condition. However, as their sleep is disrupted they usually begin to experience symptoms during the day, and a partner may witness an apnoea or point out other symptoms that occur at night. 

Symptoms include:

  • Constant tiredness
  • Lack of energy
  • Lack of concentration
  • Snoring (although not everyone who snores has sleep apnoea)
  • Frequent awakenings during the night
  • Difficulties with breathing
  • Feeling unrested after sleep
  • Gasping, choking or snorting 
  • during sleep
  • Irritability or change in personality
  • Excessive urination at night (nocturia)
  • Morning headaches
  • Dry mouth on waking

Complications Associated with Sleep APNOEA

People who have woken frequently during the night as a result of sleep apnoea, even without realising it, tend to feel sleepy the next day. The choking noises and the movements they make are also likely to cause serious disturbance to their partners. 

Sleepiness and lack of concentration during the day can be hazards at work, for example when operating machinery or driving. Note that there are regulations from some Departments of Transport about driving if you have sleep apnoea. 

There is some evidence that sleep apnoea may be linked to high blood pressure (hypertension), strokes and heart attacks. 

Ask your doctor's advice about carrying a medical alert card. If you have serious sleep apnoea and you become unconscious (for example following an accident), you might need to be put on CPAP treatment to keep you breathing steadily.


In addition to checking with the person affected, to find out what symptoms they have, the doctor may also ask the person’s partner to describe the symptoms they have seen and heard. Sometimes the person themselves may be unaware that they have a problem, but their partner may have actually seen them having an episode of apnoea. 

The doctor will also assess the type of sleepiness a person is experiencing, to work out whether sleep apnoea is a possible diagnosis. In sleep apnoea, daytime sleepiness occurs when a person does not want to sleep, for example when driving or when working. 

The Epworth Sleepiness Scale (ESS) is a way of measuring how likely a person is to fall asleep, in a particular situation during the daytime. It involves the patient filling out a questionnaire, and helps the doctor to find out how severe the condition is. 

A number of tests can be carried out to help diagnose sleep apnoea: 

  • A polysomnogram. This involves an overnight stay in a sleep laboratory, and records the apnoea/hypopnoea index, how much and how loudly a person is snoring, and their sleeping position. 
  • Visual observation of sleep. This enables doctors to check whether the patient is having breathing difficulties, if their breath is pausing for long periods and they are waking up. 
  • Pulse rate and the amount of oxygen in the blood. This helps detect if breathing has been disrupted. 

Other signs of sleep apnoea that tests may detect include abnormal heart rhythm or large increase in blood pressure, during the night. 

Part of the diagnosis process will involve ruling out other causes of daytime sleepiness. These can include sleep deprivation, depression, narcolepsy (a condition involving an irresistible urge to sleep at any time of day), or neurological conditions such as Parkinson’s.


Certain factors that are causing sleep apnoea, such as obesity, should be dealt with first. For example, by losing weight, the person may be cured of the condition. Changing sleeping position can help some people – sleeping on your side or front, rather than your back, discourages the tongue from rolling over the airway. 

The most effective non-invasive (non-surgical) treatment for sleep apnoea is continuous positive airway pressure (CPAP). The patient wears a soft mask over their nose and mouth, and a machine raises and regulates the pressure of the air they breathe, preventing the airway from collapsing during sleep. Many patients find that this treatment reduces daytime sleepiness and improves their concentration, although some experience facial or nasal pain. Feelings of claustrophobia sometimes occur. 

If CPAP doesn’t help a patient, or if they cannot cope with the mask, sometimes surgery is required to manage snoring and sleep apnoea. Surgery can involve correcting physiological abnormalities, such as removing nasal polyps. Other options include removing the adenoids, tonsils, or uvula (a tag of skin hanging down inside the mouth), or performing reconstructive surgery on the nose. 

Information source: NHS Direct Online Health Encyclopedia, 2005