The Genetic Predisposition for Sleep Apnea
The Genetic Predisposition for Sleep Apnea
Sleep is the single most common form of human behavior and you will spend a third of your life doing it. Sleep is an active state, generated with the brain, not a mere absence of consciousness (Martin 463). The dictionary defines sleep as “The natural periodic suspension of consciousness during which the powers of the body are restored” (Merriam-Webster). If one is waking up on an average of 400 times per night, the chances of complete body restoration are minimal.
The Greek word apnea literally means “without breath”. An estimated 30 million Americans stop breathing during their sleep sometimes 30-40 times per hour and often for a minute or longer each time. Of these, about 20 million are in the early stages, and about 10 million have progressed to a level of severity that requires treatment. According to the National Commission on Sleep Disorders Research, about 38,000 Americans die of sleep disorder related problems each year (Internal Medicine Alert 98).
Obstructive Sleep Apnea (OSA) is a potentially deadly sleep disorder, where the uvula and soft pallet collapse on the back wall of the upper airway causing the cessation of breathing and a drop in blood pressure. The heart’s need for oxygen increases during apnea episodes, when someone stops breathing carbon dioxide slowly builds up in the bloodstream and the oxygen level quickly decreases (Melville 852). Eventually a signal from the brain triggers the body to partially wake up, this action causes blood pressure to increase, breathing then resumes, and the cycle begins again.
Once the breathing resumes the oxygen level begins to raise, the heart starts pumping much faster than normal, raising the blood pressure to dangerously high levels. These occurrences night after night increase the risk of damaging small organs and can trigger small strokes. There are three types of apnea: Obstructive Sleep Apnea (OSA), the most common, caused when the soft tissue in the rear of the throat collapses and closes. The second type is Central Sleep Apnea (CSA); instead of the airway collapsing the brain fails to signal the muscles to breath. It is the rarest type of apnea.
The third is Mixed Sleep Apnea (MSA); a condition marked by signs and symptoms of both OSA and CSA. It often begins as CSA and develops into the obstructive form. Mixed Sleep Apnea may also result from OSA as hypoxia and hypercapnia induce signs and symptoms of the central form (Mosby’s Medical Dictionary). With each apnea event, the brain briefly awakes sleep apnea victims from sleep in order for them to resume breathing, therefore sleep is extremely fragmented and of poor quality. Untreated, sleep apnea can cause high blood pressure and other cardiovascular diseases, 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. There are several signs of sleep apnea. One example is when a person sleeps; they have a very pronounced snore. It is more like a loud and sudden snort. This “gasp for air” is literally a life saver when the mouth and throat muscles tense up to allow air back into the body. Most sleepers are unaware of this occurrence, although it often shakes their bed partners, roommates, and even neighbors to the core.
Another sign is when a person falls asleep at inappropriate times like work or in class. In adults, dry mouth, snoring, fatigue, sweaty or restless sleep and gasping awake are warning signs of apnea and should be checked by a doctor. There are many health issues and long- term effects for patients such as high blood pressure. As the body struggles for oxygen, its’ carbon dioxide level within the blood shoots up. This wakes up the sleeper momentarily so that he can start to breath properly again. As this pattern repeats itself throughout the night, the heart is forced to work harder, thus the rise in blood pressure.
Over the years, sleep apnea and the stress it places on the heart along with the rise in blood pressure can lead to serious heart disease or even heart failure. Strokes also become a health risk if the blood pressure becomes high enough and goes undetected. Many people who struggle with sleep apnea also tend to be obese and struggle to lose weight. Studies have shown that many who suffer with sleep apnea were overweight to begin with and that weight may be a contributing factor. Weight can become an issue after sleep apnea has occurred. The body’s metabolism changes when it is asleep and oxygen deprived.
The metabolism stops functioning properly, and more work is required to burn calories. People who feel sluggish tend to eat more and exercise. Another symptom of long-term effects of sleep apnea is the shift in serotonin, which holds a role in both healthy sleep and mood. When the serotonin becomes imbalanced, our natural state of sleep and mood become imbalanced. Without proper balance of serotonin, depression becomes a real struggle for many sleep apnea sufferers. Sleep apnea makes keeping up with daily routines very difficult. The lack of sleep takes a toll on work and school performance.
It also affects social relationships since there is no energy left at the end of the day to spend time with friends and loved ones. Long-term sleep deprivation can cause anyone to feel weak and clumsy. This is in part because the nervous system and the brain are fatigued. Delayed reaction kicks in, and more injuries and accidents occur. In children, however, manifestations of sleep deprivation due to any cause, including sleep disordered breathing, is quite different from adults and includes: inattention, hyperactivity, impulsivity, social difficulties, disruptive behavior, and often bad grades.
Many children who suffer from sleep disorders have a parent with sleep apnea (Comprehensive Sleep Wellness Center). According to the National Center on Sleep Disorders Research, patients who suffer from sleep apnea may endow a genetic disposition to the disorder to any offspring, as it is not uncommon for members of the same family to suffer from the same form of sleep apnea. Although scientists have just recently begun to research this phenomenon, several scientific hypotheses have been offered.
The first, and most widely accepted hypothesis, asserts a link between obesity and sleep apnea. Patients who suffer from obesity are more likely to suffer from sleep apnea, and because obesity is often caused by environmental factors, it stands to reason that members of the same family are more likely to be obese and thus suffer from sleep apnea. In addition, current research asserts that nearly half of the genetic variance in the sleep apnea hyperpnoea index, an index that explains the cause and likeliness of sleep apnea, is shared with phenotypes of obesity.
Obesity often affects the function of upper airway muscles, ventilator control and conditions of sleep in patients, so it is possible that obesity predisposes a patient to sleep apnea. It is a misconception to say that obesity is the only cause of sleep apnea. There is a high correlation between obesity and sleep apnea, but there are people with sleep apnea who are not obese. For these people, the liver damage related to sleep apnea is no greater or less than for obese patients. It is the severity of the sleep apnea that seems to determine the damage.
According to “Medical News Today,” Vsevolod Y. Polotsky, M. D. , Ph. D. , of Johns Hopkins’ Asthma and Allergy Center said, “Our data suggests that patients with OSA and severe nocturnal hypoxemia should be screened for liver disease and, conversely, patients with liver disease should be screened for Obstructive Sleep Apnea. The American Medical Network describes one study by Dr. Lawrence Serfaty and colleagues that was conducted with 163 patients in a sleep unit of a hospital. Sleep studies showed that 44 had severe OSA, 84 had moderate OSA and 35 had no evidence of OSA.
Testing revealed that liver tests were abnormal in 32 percent of those with severe OSA, 18 percent of those with moderate OSA and 8. 6 percent with no OSA. (Thomas) The only way to reliably diagnose OSA is to undergo an overnight sleep study in a sleep laboratory. This involves a series of “stick on” sensors that detect what stage of sleep you are in, how well you are breathing, and how hard you are working to breathe. Based on the information collected from the sleep study it can be determined if you have obstructive sleep apnea and how severe it is.
The first line of treatment for obstructive sleep apnea is continuous positive airway pressure (CPAP). This involves the use of a nose mask to deliver air pressure to your upper airway to “stent” it open and prevent its collapse. This can “cure” your sleep apnea and bring the increased risk for heart attack, stroke and death back to where it would be without obstructive sleep apnea. In circumstances where CPAP cannot be used, second line options (depending on the severity of your disease) include dental appliances and surgery. There are several different kinds of surgery for sleep apnea, and some work better than others.
It is advised that you seek the council of a sleep medicine physician prior to committing to anything drastic. Treatment can reduce the mean blood pressure by approximately 10 points (Sleepwellnesscenter. com) . With treatment to eliminate sleep apnea, these outcomes can be reversed and patients can resume his or her healthy and productive years. Treatment of sleep apnea also prevents the strain placed on the heart and lungs by recurrent drops in oxygen and repeated awakenings during the night, which can result in hypertension and heart disease.
Although sleep apnea cannot directly result in death, the side effects and symptoms of sleep apnea may result in fatality. Researchers report that each year, nearly 1,400 traffic fatalities occur due to sleep apnea. Generally, the driver involved suffers from a lack of sleep, and therefore may be distracted or drowsy while behind the wheel. In addition, sleep apnea can trigger larger health issues if left untreated, including high blood pressure, memory problems, weight gain, cardiovascular disease, impotency and headaches, all of which increase the likelihood of fatality in the patient.
University/College: University of Chicago
Type of paper: Thesis/Dissertation Chapter
Date: 2 October 2016
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