What causes sleep apnea?

Sleep apnea is most often caused when an excess amount of fatty tissue accumulates in the airway and causes it to be narrowed. With a narrowed airway, the person continues his or her efforts to breathe, but air cannot easily flow into or out of the nose or mouth. This narrowing of the airways results in heavy snoring, periods of no breathing, and frequent arousals (causing abrupt changes from deep sleep to light sleep). Ingestion of alcohol and sleeping pills increases the frequency and duration of breathing pauses in people with sleep apnea.

In some cases sleep apnea occurs even if no airway obstruction or snoring is present. This form of sleep apnea is called central sleep apnea and is caused by a loss of perfect control over breathing by the brain. In both obstructive and central sleep apnea, obesity is the major risk factor and weigh loss is the most important aspect of long-term management. People with sleep apnea experience periods of anoxia (oxygen deprivation of the brain), with each episode ending in arousal and a reinitiation of breathing. Seldom does the sufferer awaken enough to be aware of the problem. However, the combination of frequent periods of oxygen deprivation (20 to several hundreds of times per night) and the greatly disturbed sleep can greatly diminish the quality of life and lead to some very serious problems, including diabetes! Sleep apnea needs to be taken seriously, and it should always be treated.

Weight loss is also a critical part of the successful management of sleep apnea. Beyond that, the most common treatment of sleep apnea is the use of nasal continuous positive airway pressure (CPAP). In this procedure, the patient wears a mask over the nose during sleep, and pressure from an air blower forces air through the nasal passages. The air pressure is adjusted so that it is just enough to prevent the throat from collapsing during sleep. The pressure is constant and continuous. Nasal CPAP prevents airway closure while in use, but apnea episodes return when CPAP is stopped or if it is used improperly. The CPAC equipment is readily available and can be obtained with a doctor's prescription. It takes quite a while to get used to CPAP, but this method usually works well. In fact, I have had many patients who feel that they have been given a new lease on life with it.

There are two types of sleep apnea: obstructive sleep apnea, and central sleep apnea. Obstructive sleep apnea is the more common type, and is caused when the back of the mouth or throat is blocked. Individuals with obstructive sleep apnea stop breathing several times when they are asleep, because their airway is blocked. The blockage is often a combination of something structural, like large tonsils, a large or thick tongue, or a large uvula (the piece of tissue that hangs down from the top of your mouth), and the relaxation of the muscles in the mouth and throat when you sleep. These muscles can relax for many reasons – from laying on your back, weight gain, alcohol or medication, or simply being asleep. In most people their obstructive sleep apnea gets worse when they lie on their back (where gravity pushes everything backwards and makes the throat more narrow) or when they are in REM sleep. REM sleep is where all muscles are paralyzed (so you do not act out your dreams) and makes throat muscles relax even more. The combination of the physical blocking of the throat with the relaxed muscles creates a narrower than normal opening, making it more difficult to breathe normally. Central Sleep apnea is much different The respiratory centers of the brain mistakenly think that the lungs are full of air and are often not sending the signal from the brain to the lungs to breathe. This can be caused by a brain tumor, brain malformation, lung disease (or in some cases cardiac disease). This type of sleep apnea much less common and is far more difficult to treat.

Obstructive Sleep Apnea (OSA) is caused by vibration of soft tissue in the throat. During sleep, the muscles lining the upper airway relax, allowing the soft tissue to vibrate as we breathe (this make the noises we call snoring). If the tissue vibrates so much that it actually blocks (obstructs) airflow, the result is the disease we call OSA. OSA is a serious disease, and needs to be treated!

Obstructive sleep apnea usually occurs when the throat muscles and tongue relax during sleep and partially or completely block the airway. When you stop breathing or have reduced flow of air into your lungs during sleep, the amount of oxygen in your blood decreases briefly.

Bone deformities, enlarged tissues

Obstructive sleep apnea can also occur if you have bone deformities or enlarged tissues in your nose, mouth or throat. For example, you may have enlarged tonsils. During the day when you are awake and standing up, this may not cause problems. But when you lie down at night, the tonsils can press down on your airway, narrowing it and causing sleep apnea.

In children, the main cause of sleep apnea is large tonsils or adenoids.

Other causes

Other things that may contribute to sleep apnea include:

• Drinking alcohol, which affects the part of the brain that controls breathing. This may relax the breathing muscles and cause a narrowing of the airway and sleep apnea.
• Obesity. Fat in the neck area can press down on the tissues around the airways. This narrows the airways and can cause sleep apnea. About 7 out of 10 people who have sleep apnea are obese.
• Some medicines that are taken for conditions such as allergies, long-term pain, insomnia or anxiety. These medicines, such as narcotics, can also relax the muscles and tissues in the throat, causing it to narrow.