Definition and causes of sleep apnoea

Sleep apnoea is a disorder where breathing ceases for shorter or longer spells during sleep. Apnoea means stopping breathing, which lasts at least 10 seconds and can last up to 60 seconds. When breathing stops for so long, the person who suffers from sleep apnoea, will wake up many times during the night while the person might wake up fully during shorter apnoea period.

For the condition to be defined Sleep apnoea, there must be at least five apnoea periods per hour of sleep leading to the oxygen saturation level in the blood dropping to not more than 5%. For each such apnoea period the person wakes up briefly depriving the person the important deep sleep. The affected persons never get a good night's sleep and become tired and indisposed during the day.

There are three types of sleep apnoea:

• Obstructive sleep apnoea: This is the most common form. Breathing is normal but air does not reach the lungs due to a blockage in the air passage in the nose and/or the throat (pharynx) is blocked. This typically occurs during REM sleep (Rapid Eye Movement sleep) where the muscles of the throat over-relax, (see also the article "When sleep becomes a problem"). There is a smooth transition between regular snoring and mild obstructive sleep apnoea.
   
• Central sleep apnoea: This is very rare. There is no breathing movements, and therefore no air reaching the lungs. The reason for the lack of breathing movements is the lack of sensory signal from the brain to the chest muscles and diaphragm muscle which temporarily cease to work.
   
• Mixed sleep apnoea: This is a mixture of obstructive and central sleep apnoea.

Sleep apnoea occurs in about 1% of the population. It is more common in men and occurs particularly in the age 30-60 years. Sleep apnoea can also be seen in children, particularly if they suffer from enlarged tonsils or adenoids. Persons with sleep apnoea also often have problems with snoring. Snoring stems from lack of space in the throat airway and the less space the more intense the snoring. There is an increased risk of both snoring and sleep apnoea in overweight persons.
 

Symptoms of sleep apnoea

If you share a room with someone snoring strongly you will probably have noticed breaks in the snoring of up to one minute at the time which indicates sleep apnoea.

Person who suffers from sleep apnoea may not remember all the times he or she has been briefly awake during the night. During the day, however, there are often significant problems, despite many hours of sleep. The problems are typically:

• Pronounced fatigue with the urge to sleep throughout the whole day.
• Trouble to stay awake for example during meetings, tuition or driving a car.
• Impaired concentration.
• Poor memory.
• Irritability.

Many people with sleep apnoea also have high blood pressure and a body mass index greater than 25 (see also BMI), reflecting overweight. The neck circumference is often large in relation to the height.

Precautions and diagnosis of Sleep apnoea

If you suspect that you could be suffering from sleep apnoea, you should consult your general practitioner who can refer you for further examinations. If there is pronounced fatigue and a tendency to fall asleep or dose off in situations without physical activity, one should take great care if driving or operating machinery. Possibly such activities should be abandoned altogether.

There are different methods available to diagnose sleep apnoea. The person might be observed or monitored during sleep. The person must have a pulsoximeter on a finger, facilitating the measurement of oxygen saturation in the blood. It may be necessary to make a more advanced study, called a polysomnography. Here the person is monitored during sleep. The breathing volume and breathing muscle activity is measured together with the sleep level which is measured with a electroencephalogram (EEG), where electrodes positioned on the scalp measure the activity in different areas of the brain. 

Examination should be conducted by an otorhinolaryngologist (specialist in ear-nose-throat problems) to determine the airway space situation in the nose and throat. 

Treatment of sleep apnoea

• Weight loss: If you are overweight, a weight loss might alone create sufficient space in the throat to improve or eliminate the problem.
• Avoid alcohol and sedative drugs (eg. sleeping pills and certain types of anti-histamine) before bedtime.
• An individual special teeth device or a tongue position device might help some.
• CPAP (Continuous Positive Airway Pressure): This is a special machine which mechanically assists the breathing by placing a mask over the nose and/or mouth keeping the pressure in the upper respiratory tract above atmospheric pressure preventing the airways from collapsing during sleep. However, it can be somewhat annoying to have to sleep with such a mask with noisy mechanical parts. If the patient can get used to this most experience good efficacy of this treatment.
• Operation of the soft palate or facial skeleton to create more space. This has been tried in some patients, but with very varying results.
• In the very severe cases where other treatment is not enough, surgery to the throat might be necessary making a hole in the airway (a tracheostomy) to allow free flow of air to the lungs.

Outlook and complications

Most can be helped with the above treatment, but until treatment has begun, there is great risk by driving or operating dangerous machinery. There may problems holding a job or an occupation because of extreme fatigue. Socially there may also be problems with patients unable to stay awake in a cinema or theater or simply falling asleep in the middle of conversations

Severe sleep apnoea is potentially serious and may lead to hypertension, hart failure or stroke.

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