What causes obstructive sleep apnea?
Obstructive sleep apnea is caused by repetitive upper airway obstruction during sleep as a result of narrowing of the respiratory passages. Patients with the disorder are most often overweight, with associated peripharyngeal infiltration of fat and/or increased size of the soft palate and tongue. Some patients have airway obstruction because of a diminutive or receding jaw that results in insufficient room for the tongue. These anatomic abnormalities decrease the cross-sectional
area of the upper airway. Decreased airway muscle tone during sleep and the pull of gravity in the supine position further decrease airway size, thereby impeding air flow during respiration.
Obstructive sleep apnea occurs when part of the airway is closed off (usually at the back of the throat) while a person is trying to inhale during sleep. People whose airways are slightly narrower than average are more likely to be affected by OSA. Obesity, especially obesity in the neck, can increase the risk of developing OSA, because the fat tissue tends to narrow the airway. In some people, the airway is blocked by enlarged tonsils, an enlarged tongue, jaw deformities, or growths in the neck that compress the airway. Blocked nasal passages may also play a part in some people.
For reasons that are still unclear, in deep sleep, breathing can stop for a period of time (often more than 10 seconds). These periods of lack of breathing, or apneas, are followed by sudden attempts to breathe. These attempts are accompanied by a change to a lighter stage of sleep. The result is fragmented sleep that is not restful, leading to excessive daytime drowsiness. When a person begins to inhale, the expansion of the lungs lowers the air pressure inside the airway. If the muscles that keep the airway open are not working hard enough, the airway narrows and may collapse, shutting off the supply of air to the lungs. OSA occurs during sleep because the neck muscles that keep the airway open are not as active then. Congestion in the nose can make collapse more likely, since the extra effort needed to inhale will lower the pressure in the airway even more. Drinking alcohol or taking tranquilizers in the evening worsens this situation, because these cause the neck muscles to relax. (These drugs also lower the "respiratory drive" in the nervous system, reducing breathing rate and strength.)
In children, the most common cause of obstructive sleep apnea is enlarged tonsils and adenoids in the upper airway. Infections may cause these glands to enlarge. Large adenoids may completely block the nasal passages and make breathing through the nose difficult or impossible. There are many muscles in the head and neck that help to keep the airway open. When a person (child or adult) falls asleep, muscle tone tends to decrease, thus, allowing tissues to fold closer together. If the airway is partially closed (by enlarged glands) while awake, falling asleep may result in a completely closed passage. Obesity may cause obstructive sleep apnea. While a common cause in adults, obesity is a far less common reason for obstructive sleep apnea in children. A rare cause of obstructive sleep apnea in children is a tumor or growth in the airway.
More information on sleep apnea
What is sleep apnea? - Sleep apnea is a disorder in which a person stops breathing during the night. Sleep apnea means cessation of breath characterized by repetitive episodes of upper airway obstruction.
What types of sleep apnea are there? - There are three types of sleep apnea, including obstructive sleep apnea (OSA), central sleep apnea, mixed sleep apnea.
What is obstructive sleep apnea? - Obstructive sleep apnea is a disorder in which complete or partial obstruction of the airway during sleep causes loud snoring, oxyhemoglobin desaturations and frequent arousals.
What causes obstructive sleep apnea? - Obstructive sleep apnea is caused by repetitive upper airway obstruction during sleep as a result of narrowing of the respiratory passages.
What're the symptoms of obstructive sleep apnea? - Symptoms of obstructive sleep apnea include loud snoring, Daytime sleepiness, memory changes, depression, and irritability.
What is central sleep apnea? - Central sleep apnea is a sleep breathing disorder that occurs when the brain fails to send the appropriate signals to the breathing muscles to initiate respirations.
What causes central sleep apnea? - Conditions that can cause sentral sleep apnea include bulbar poliomyelitis, encephalitis affecting the brainstem, neurodegenerative illnesses.
What're the symptoms of central sleep apnea? - Symptoms of central sleep apnea include extreme exhaustion and sleepiness during daylight hours, early morning headaches, lack of concentration, and memory loss.
What are the risk factors for sleep apnea? - There are several factors that may predispose a person towards sleep apnea, including gender, age, ethnicity, geography, obesity, immune abnormalities.
What are the complications of sleep apnea? - Sleep apnea is a potentially life-threatening condition because there are interruptions in breathing during sleep.
How is sleep apnea diagnosed? - A sleep test, called polysomnography is done to diagnose sleep apnea. Confirmation of the diagnosis requires making measurements while the person sleeps.
What's the treatment to stop sleep apnea? - Treatment for sleep apnea is determined based on the individual's specific circumstances and can include behavioral changes, physical therapy and surgery.
What surgeries are available to cure sleep apnea? - Surgeries to stop sleep apnea include uvulopalatopharyngoplasty, laser-assisted uvulopalatoplasty, tracheostomy, radiofrequency ablation.
What about the CPAP therapy for sleep apnea? - The most effective treatment for sleep apnea is nasal continuous positive airflow pressure (CPAP) therapy.