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Virend Somers, M.D., Ph.D., a Mayo Clinic cardiologist and sleep medicine physician, takes issue with the idea of people "dying peacefully in their sleep." In fact, the phrase bothers him quite a bit.
When it comes to deaths that result from sleep disorders, he says, "There's nothing peaceful about it. Sleep is supposed to be a time for the body to rest and recharge. Death during sleep may not necessarily be natural or peaceful."
Dr. Somers' job as the director of the Sleep Disorders Research Laboratory at Mayo Clinic Rochester is to identify and research connections among sleep disorders, heart disease and sudden death. It's this connect-the-dots medical mystery that drives his work.
"People often don't link death during sleep to sleep disorders and heart disease, but as many as 60 percent of cardiovascular deaths have a sleep link. Unfortunately, the amount of research being done to better understand this link is miniscule compared with other types of cardiovascular research," says Dr. Somers. The explanation for this research gap is simple: There are very few cardiologists who also are trained in sleep medicine.
According to Dr. Somers, the reason for this shortage of dual-trained doctors isn't lack of interest, but lack of funding. "You can't research the problem if you don't have the funding to set up labs, hire researchers and conduct the studies," he says. At times, the problem of how to fund the studies is as daunting as identifying the links between sleep and heart disease. "Sleep apnea is a disease that's as prevalent as diabetes, yet research funding in this area pales in comparison. It's unfortunate and frustrating," he says.
Sleep disorders medicine is a relatively new field of study, gaining public awareness in the mid-to-late 1970s. It was around that time that people started hearing of a disorder called obstructive sleep apnea (OSA). Initially, OSA — a disorder in which breathing is briefly but repeatedly interrupted during sleep — was thought to be a rare condition affecting few. Original projections of its prevalence couldn't have been more wrong.
We now know that an estimated 15 million Americans — three-fourths of them men — have OSA. Only about 10 percent of them are being treated for their condition. Of the sleep disorders that are thought to have an impact on the heart, OSA probably has the most obvious cause-and-effect connection.
With OSA, the muscles at the back of the throat sag during sleep causing blockage of the throat. This blockage often is signaled by loud snoring and periods of stopped breathing. This cycle of sagging tissues, blocked airway, loud snoring, stopped breathing and then abrupt awakening can occur hundreds of times a night, leading to less-than-restful sleep. Unfortunately, over time, OSA also can lead to high blood pressure, heart disease and heart failure.
Blood pressure rises as a result of OSA through a series of chain reactions. When you stop breathing, the oxygen level in your body falls and alerts receptors in your brain. Your brain then sends a signal to your nervous system instructing blood vessels to constrict in order to increase the flow of oxygen to priority areas of your heart and brain. Over time, this alert signal remains constant, leading to ongoing constriction of the blood vessels, which, in turn, permanently raises blood pressure. Death during sleep, or daytime hypertension, atrial fibrillation and heart failure, can result from this unfortunate series of events.
Although this eventual rise in blood pressure is a complicated physiologic process, identifying those at risk of OSA usually isn't complicated at all. Telltale signs of OSA occur in people — usually men over 40 — who tend to be overweight, have daytime sleepiness, have enlarged tonsils or adenoids, have a thick neck, have a family history of sleep apnea and who use alcohol, sedatives or tranquilizers. This description fits many, but not all, of those with OSA.
The effects of OSA (obstructive sleep apnea) on the heart seem clear. What's less clear is why central sleep apnea (CSA) can also lead to heart failure and death during sleep. CSA isn't caused by an obstruction as is OSA. CSA is a condition in which the brain fails to signal for breath during sleep. The end results are the same. Like OSA, CSA also causes high blood pressure and is linked with heart disease and heart failure, but the reasons for its occurrence are less understood.
Why does the brain essentially miss its cue to send signals for breath during sleep? Why does the brain send signals for breath when a person is awake but not when asleep? Why does CSA affect younger people who are seemingly fit and healthy? And why is CSA more common than OSA among heart failure patients? Perhaps the biggest question of all is: Does CSA cause heart disease or does heart disease cause CSA?
"We do know that if you have sleep apnea, the chances that you'll develop high blood pressure and heart disease increase significantly," says Dr. Somers. "We are now finding that CSA, which was previously thought of as a symptom of heart failure, may in fact contribute to the development of heart failure in people at risk."
Dr. Somers and his team are making headway with a little help. By combining efforts with colleagues in the areas of sleep medicine, gastroenterology, endocrinology, surgery, cardiology and molecular biology, Dr. Somers hopes to find solutions.
The Sleep Disorders Center at Mayo Clinic Rochester offers Dr. Somers the perfect venue to test his theories on patients with known sleep disorders.
"At the Sleep Disorders Center we can conduct both sleep and cardiovascular tests. And since the center has a lab, we can do blood testing, study white blood cell biology and do tissue biopsies to test theories," says Dr. Somers. "One thing we're currently investigating is why sleep deprivation accelerates the aging process. A lack of sleep actually ages the body and makes a person's chemical structure behave like someone much older.
"We also know that sleep deprivation as a result of sleep apnea leads to weight gain and we're currently studying how and why fat cells change. What is it about sleep deprivation that encourages weight gain?" he asks. This question has led him to collaborate with colleagues in endocrinology and molecular biology.
Because weight gain leads to a host of other problems such as high blood pressure, heart disease and diabetes, Dr. Somers says, "We need to understand this link between sleep and weight gain so that we can find better ways to treat the problem and prevent additional diseases."
To help answer this question, Dr. Somers calls on his colleagues in gastroenterology and surgery to investigate ways that bariatric surgery might help overweight patients lose weight and improve the symptoms of OSA. But, it's more than just figuring out a way to help people lose weight. He wants to get to the root of why people with apnea gain weight. He theorizes that there's some chemical culprit at work, leading people with apnea to eat more and move less.
Still another area of ongoing research takes place with his cardiology and pulmonary colleagues. We know that there's a very close connection among the heart, the brain and breathing. For people with CSA, we know that this connection falters at times, and missed signals from the brain lead to missed breaths during sleep. To research this problem, Dr. Somers and his fellow cardiologists study whether pacemakers may help some CSA patients.
"Studies show that changing the effect of breathing could help those with even modest CSA," says Dr. Somers. With a 50 percent reduction in incidence of those studied, it seems he's on the right track.
Dr. Somers says that with benefactor support, he and his colleagues could dive into the never-ending list of questions to find answers and save lives.
If this were Oz and the wizard was granting wishes, Dr. Somers would ask for funding to build an integrated cardiovascular and sleep research center. He would ask for funding to further the research on why people die during sleep and to more fully investigate the link between sleep deprivation and conditions such as weight gain and diabetes. He'd ask for funding to buy the equipment needed to improve work flow and ensure economy of efforts. Dr. Somers and his research team hope that one day soon, their work will be promoted through philanthropic means.
We know that obstructive and central sleep apnea aren't the kinds of disorders that'll go away if you "just sleep on them." Quite the contrary. We also know that those suffering with apnea have several possible treatment solutions at their disposal. Matching the right solution with the right patient is what doctors at Mayo Clinic Sleep Disorders Center specialize in.
Among their arsenal of sleep solutions are: Continuous Positive Airway Pressure (CPAP), dental devices, Uvulopalatopharyngoplasty (UPPP), Laserassisted Uvulopalatoplasty (LAUP) and Radiofrequency Ablation (RFA), all of which can be used for those who have obstructive sleep apnea — a disorder in which an obstruction in the airway blocks breathing during sleep. Treatments for central sleep apnea (CSA), a disorder where the brain fails to signal for breath during sleep, are limited and may include variations on CPAP, nasal oxygen and drugs that help modify breathing patterns.
CPAP – With CPAP, a machine delivers air pressure through a mask worn over your nose while you sleep. The supplied air pressure helps keep the upper airway open, preventing apnea and snoring.
Dental devices – Certain dental devices can be worn at night to help bring the jaw forward and open the airway passage.
UPPP – During this surgical procedure, tissue from the rear of your mouth and the top of your throat is removed. Your tonsils and adenoids are usually removed as well. This surgery keeps throat structures from blocking the airway and causing vibrating and snoring.
LAUP – This procedure uses a laser to remove part of your soft palate and shorten the uvula (the tissue that hangs down in the back of your throat). This eliminates excess tissue that may obstruct your airway, causing snoring and sleep apnea.
RFA – Radiofrequency energy removes tissue from your uvula, soft palate and tongue. This procedure may decrease snoring and your risk of sleep apnea. Remedies vary for those with central sleep apnea. First and foremost, those with CSA may be tested for associated medical problems such as heart or neuromuscular disorders to ensure that other culprits aren't at the root of their sleep problem. Once other causes are dismissed, people with CSA can try using supplemental oxygen or CPAP.
Supplemental oxygen – Supplemental oxygen can be used while you sleep. Various forms of oxygen are available as well as different devices to deliver the oxygen to your lungs.
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