Snoring not just a nuisance; it's a danger sign

Some people first suspect they have obstructive sleep apnea when their significant other complains about excessive snoring, or tells them they stop breathing many times during the night.

Others figure it out when their daytime sleepiness gets so bad they fall asleep at meetings or have a car accident.

Still others among the 18 million Americans with obstructive sleep apnea don't believe they have it until they are finally tested in a sleep lab, get treatment, usually with a device called CPAP, and get the first good night's sleep they've had in years.

Thanks to a growing body of evidence, including two papers in last week's New England Journal of Medicine, doctors are beginning to realize just how dangerous obstructive sleep apnea can be -- and how tightly linked it may be not ''just" to heart disease and stroke, as had been long suspected, but also to problems such as obesity, diabetes, and brain damage.

Some doctors even think sleep apnea might be part of ''metabolic syndrome," the cluster of symptoms such as obesity, high blood pressure, glucose intolerance, and high cholesterol that raises the risk of cardiovascular disease. ''Sleep apnea is intrinsically related to each of those factors," said Dr. H. Klar Yaggi, an assistant professor at the Yale University School of Medicine and first author of one of the new papers.

Obstructive sleep apnea happens when muscles, including those in the throat, relax during sleep. It's particularly common among older people and those who are overweight, whose throats are already narrowed by fat deposits. As the muscles relax, allowing the upper airway to collapse, the effort of trying to breathe makes the sleeper partially wake up hundreds of times a night. (Children can get obstructive sleep apnea, too, usually because their tonsils and adenoids are enlarged.)

Though each cessation of breathing often lasts a few seconds and the sleeper typically is totally unaware of it, the body interprets it as an emergency. As blood oxygen falls, there is a surge of adrenaline, which causes the heart to beat faster and blood pressure to rise steeply. High blood pressure has long been known to cause strokes.

The rapid rise and fall of oxygen levels, called intermittent hypoxia, is more dangerous than a constant low level of oxygen, in part because it causes inflammation, an underlying cause of many problems, including the clogging of coronary arteries.

''It's the back and forth that causes the problems," said Dr. David P. White, director of the sleep disorders program at Brigham and Women's Hospital, adding that research shows that people with sleep apnea have a 27 percent increased risk of heart attack and a 240 percent increased risk of congestive heart failure.

Other ominous research suggests a link between sleep apnea and brain damage. Animal studies have shown that intermittent hypoxia ''is very injurious," to the cerebellum, the part of the brain that controls blood pressure and breathing, and to the hippocampus, which controls memory, said Ron Harper, a neurobiologist at the David Geffen School of Medicine at UCLA.

In children with sleep apnea, surgically removing the tonsils often leads to a ''dramatic recovery" in school work, Harper said. In adults, treating sleep apnea leads to some improvement in cognitive function, but some longer term injury often remains.

If you think you have sleep apnea, see a doctor and request a polysomnography, a test done in a sleep lab overnight that can confirm an apnea diagnosis.

The most common treatment is a device called CPAP, which stands for continuous positive airway pressure. You strap it on to your face at night -- it looks a bit like an elephant's trunk -- and it forces air down your throat to keep it open.

''CPAP is not always user-friendly. Not everybody tolerates it," said Dr. Carl E. Hunt , director of the National Center on Sleep Disorders Research at the National Heart Lung and Blood Institute.

Although CPAP has not -- yet -- been linked conclusively with lower death rates from cardiovascular disease, short-term studies show it can improve sleep quality, reduce daytime sleepiness and lower blood pressure.

Surgery to remove the floppy tissue that collapses and obstructs the throat -- part of the soft palate and the uvula (that funny thing that hangs down in your throat) -- can also reduce apnea episodes.

So can a product, made by a dentist, called a mandibular advancement device. Like a retainer, it's worn at night and makes the lower jaw move forward to keep the throat from collapsing. And for people who are obese, losing 10 to 20 percent of weight can cut the severity of sleep apnea in half.

Bottom line? Don't ignore potential sleep apnea. It's a significant red flag that your health may be in danger. So, get checked. Get treated. And sweet dreams!

Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.