Sleep apnea is a breathing disorder characterized by brief interruptions of breathing during sleep. Most commonly the muscles of the upper airway fail to maintain a patient’s airway during sleep. This leads to temporary suspension of breathing, causing “gasping” and partial waking.
These episodes occur commonly during Rapid Eye Movement (REM) sleep, a sleep stage when upper airway muscles are particularly relaxed. Regular interruption of REM sleep can have a cumulative negative impact on behaviour and health.
Sleep apnea syndrome is diagnosed when more than 35 episodes of apnea occur during a seven-hour period, each apnea lasting for ten seconds or more. Approximately four percent of the male and two percent of the female population in the world suffer from moderate to severe sleep apnea syndrome. The majority of these cases have not yet been diagnosed.
There are three different types of sleep apnea:
- Obstructive Sleep Apnea (OSA) which is caused by a blockage of the airway, is the most common. This blockage is usually soft tissue in the rear of the throat, which collapses and closes the airway during sleep.
- Central Sleep Apnea - Apnea episodes can also be triggered centrally in the brain. These episodes are not caused by blocked airways, but rather that the brain fails to initiate the breathing signal to the muscles.
- Mixed Sleep Apnea is a combination of the two above.
When an apnea occurs, the oxygen level in the blood drops. Warning signals from different parts of the body will be conveyed to the brain which protectively arouses the patient from sleep. This will cause increased upper airway muscle tone and resumption of breathing. The sleep in a person suffering from sleep apnea is consequently fragmented and of poor quality. Most patients with sleep apnea are not aware of these arousals, but certainly suffer from the daytime symptoms.
Common contributing factors to obstructive sleep apnea:
- Obesity - Fatty tissue may partially occlude the airway, and breathing dynamics are changed.
- Physical abnormalities - Maxillofacial or nasopharangeal defects commonly cause obstruction of the airway.
- Age - Loss of muscle tone in the upper airway.
- Alcohol and drugs - Alcohol and several different drugs can both cause excessive muscle relaxation in the upper airway.
The symptoms of sleep apnea
Day time symptoms include:
- Excessive daytime sleepiness
- Morning headache
- Concentration problems and memory loss, especially short term memory
- Behavioural abnormalities, including aggression, shyness and hyperactivity
Night time symptoms include:
- Loud snoring, accompanied by the characteristic “gasping” during apnea episodes
- Restless sleep and nightmares
- Sweating and enuresis (bed wetting)
Sleep apnea may also be confused with other disorders including:
- Narcolepsy - A condition when the patient falls rapidly into REM sleep
- Nocturnal myoclonus - Excess muscle activity in the extremities characterised by repetitive or spastic movements during sleep
- Insomnia - sleeplessness
Complications of Sleep Apnea
There are various diseases, which can be aggravated or even caused by sleep apnea. These include coronary heart disease, myocardial infarction, stroke, arterial hypertension, thrombosis and cardiac arrhythmia.
Due to daytime sleepiness, the risk for traffic accidents is increased in sleep apnea patients.
Treatment of Sleep Apnea
There are different treatment possibilities for people suffering from sleep apnea. Where lifestyle is a contributory factor, particularly with reference to alcohol, drugs and obesity, simple behavioural modification may treat the condition successfully.
Invasive options include pharyngeal surgery, or insertion of a pacemaker to stimulate airway muscles electrically.
CPAP - Continuous Positive Airway Pressure device - is an airflow generator with a pressure regulatory system designed to deliver a continuous pressure to the airway through a mask. The increased pressure prevents collapse of the airway and normal sleep is restored.