New Study Focuses on Sleep Apnea and its Relationship to Hypertension and Stroke

Toronto (June 20, 2000) - One of the most common complaints in a marriage is the snoring spouse. According to researchers at the Toronto Rehabilitation Institute, snoring can be an indication of something much more serious: sleep apnea. Sleep apnea is a disorder where a person stops breathing repeatedly during sleep. It can actually lead to hypertension (high blood pressure) and increase the risk of having a stroke. A new study at Toronto Rehab will investigate the relationship between sleep apnea, hypertension and stroke.

Dr. Douglas Bradley, Director of the Sleep Research Laboratory at Toronto Rehab and the lead investigator of this study, says, "There is more and more evidence that sleep apnea causes elevations in blood pressure and increases the tendency for blood to clot. Both of these increase the risk of stroke. In fact, 50 per cent of people with sleep apnea have hypertension, which predisposes them to stroke and other cardiovascular diseases such as heart failure."

"We have evidence that treating sleep apnea can reduce blood pressure in hypertensive patients," says Dr. Bradley. "Unfortunately, the hypertension due to sleep apnea is relatively resistant to the usual anti-hypertensive drugs. However, some studies indicate that eliminating sleep apnea with something called continuous positive airway pressure can reduce blood pressure levels in such patients. We believe it is also possible that the early recognition and treatment of sleep apnea may even prevent the development of hypertension."

So what causes the snoring and sleep apnea. "In overweight men particularly, fat collects around the neck which tends to narrow the throat. Air rushing through this narrowing produces the sound during sleep which we hear as snoring," explains Dr. Bradley. "At the onset of sleep, the muscles that hold the throat open relax, which makes the throat narrow further. In some cases, the throat completely collapses cutting off the flow of air into the lungs. As a result, the person can stop breathing for a period of 10 to 60 seconds."

And what are the effects on a person's physical and emotional state? Dr. Bradley continues, "In order to resume breathing, the patient has to awaken to open up the throat. If this happens frequently or the episodes of apnea increase in length, the resulting lack of oxygen to the brain and disruption of sleep leads to fatigue, sleepiness, impairment of short-term memory and functional disabilities such as lack of concentration and coordination. Among patients with strokes, the presence of sleep apnea may, therefore, be of particular concern because it may further worsen their mental and physical disability, and impede their rehabilitation."

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