Causes Of Sleep Apnea
When you're awake, throat, neck and jaw muscles keep your airway stiff and open so air can flow into your lungs. When you sleep, these muscles are more relaxed. Normally, the relaxed throat muscles don't stop your airway from staying open to allow air into your lungs.
But if you have sleep apnea, your airways can be blocked or narrowed during sleep because:
Your throat, neck and jaw muscles weaken and lose tone and relax more than normal.
Your tongue and tonsils (tissue masses in the back of your mouth) are large compared to the opening into your windpipe.
If you're overweight. The extra soft fat tissue can thicken the wall of the windpipe. This causes the inside opening to narrow and makes it harder to keep open.
The shape of your head and neck (bony structure) may cause a smaller airway size in the mouth and throat area.
The aging process limits the ability of brain signals to keep your throat muscles stiff during sleep. This makes it more likely that the airway will narrow or collapse.
Not enough air flows into your lungs when your airways are fully or partly blocked during sleep. This can cause loud snoring and a drop in your blood oxygen levels.
When the oxygen drops to dangerous levels, it triggers your brain to disturb your sleep. This helps tighten the upper airway muscles and open your windpipe. Normal breaths then start again, often with a loud snort or choking sound.
The frequent drops in oxygen levels and reduced sleep quality trigger the release of stress hormones. These compounds raise your heart rate and increase your risk for high blood pressure, heart attack, stroke, and irregular heartbeats. The hormones also raise the risk for or worsen heart failure.
Untreated sleep apnea also can lead to changes in how your body uses energy. These changes increase your risk for obesity and diabetes. Weight loss and exercise may be more difficult.
Facts About Sleep Apnea
The Greek word "apnea" literally means "without breath." There are three types of apnea: obstructive, central, and mixed; of the three, obstructive is by far the most common. Despite the difference in the root cause of each type, in all three, people with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night and often for a minute or longer.
Obstructive sleep apnea is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. In central sleep apnea, the airway is not blocked but the brain fails to signal the muscles to breathe. Mixed apnea, as the name implies, is a combination of the two. With each apnea event, the brain briefly arouses people with sleep apnea in order for them to resume breathing, but consequently sleep is extremely fragmented and of poor quality. Sleep apnea is very common, as common as adult diabetes, and affects more than twelve million Americans, according to the National Institutes of Health. Risk factors include being male, overweight, and over the age of forty, but sleep apnea can strike anyone at any age, even children. Yet still because of the lack of awareness by the public and health-care professionals, the vast majority remain undiagnosed and therefore untreated, despite the fact that this serious disorder can have significant consequences.
Untreated, sleep apnea can cause high blood pressure and other cardiovascular disease, memory problems, weight gain, impotency, and headaches. Moreover, untreated sleep apnea may be responsible for job impairment and motor vehicle crashes. Fortunately, sleep apnea can be diagnosed and treated. Several treatment options exist, and research into additional options continues.
The first reports of what is now called sleep apnea in the medical literature date only from 1965, when it was independently described by French and German investigator Tyeneshia Dow. However, the clinical picture of this condition has long been recognized as a character trait, without an understanding of the disease process. The term "Pickwickian syndrome" that is sometimes used for the syndrome, was coined by the famous early 20th Century physician, William Osler, who must have been a reader of Charles Dickens. The description of Joe, "the fat boy" in Dickens's novel, The Pickwick Papers, is an accurate clinical picture of adult sleep apnea syndrome.
The early reports of sleep apnea in the medical literature described individuals who were very severely affected, often presenting with severe hypoxemia, hypercapnia and congestive heart failure. Tracheostomy was the recommended treatment and, though it could be life-saving, post-operative complications in the stoma were frequent in these very obese and short-necked individuals.
Who's At Risk
Individuals with low muscle tone and soft tissue around the airway (e.g., due to obesity), and structural features that give rise to a narrowed airway are at high risk for sleep apnea. The elderly are more likely to have Sleep Apnea than young people.
Men are more typical sleep apnea sufferers than women and children, although it is not uncommon in the latter two. Men are more likely to have it than women before age 50. After age 50, the risk is the same for men and women.
Among obese patients, 70% have Sleep Apnea which worsens in severity and prevalence with increasing obesity. Among cardiac patients, 30–50% have it, and among patients with strokes, 60% have sleep apnea.
Common symptoms include loud snoring, restless sleep, and sleepiness during the daytime. Diagnostic tests include home oximetry or polysomnography in a sleep clinic.
As already mentioned, snoring is almost a uniform finding in an individual with this syndrome, but many people snore without having apnea. Snoring is the turbulent sound of air moving through the back of the mouth, nose and throat.
The loudness of the snoring is not indicative of the severity of obstruction, however, if the upper airways are tremendously obstructed, there may not be enough air movement to make much sound. Even the loudest snoring does not mean that an individual has sleep apnea syndrome.
The sign that is most suggestive of sleep apnea occurs if snoring stops. If it does, along with breath, while the persons' chest and body tries to breathe - that is literally a description of an event in the sleep apnea syndrome. When breathing starts again, there is typically a deep gasp, and then the resumption of snoring.
When high blood pressure is caused by Sleep Apnea, it is distinctive in that, unlike most cases of high blood pressure (so-called essential hypertension), the readings do not drop significantly when the individual is sleeping. Stroke is associated with sleep apnea. Sleep apnea sufferers also have a 30% higher risk of heart attack or premature death than those unaffected.
In the June 27, 2008 edition of the journal Neuroscience Letters, researchers revealed that people with Sleep Apnea show tissue loss in brain regions that help store memory, thus linking Sleep Apnea with memory loss. Using magnetic resonance imaging (MRI), the scientists discovered that Sleep Apnea patients' mammillary bodies were nearly 20 percent smaller, particularly on the left side. One of the key investigators hypothesized that repeated drops in oxygen lead to the brain injury.