March 17, 2007	Saturday	Safar 27, 1428

NEW YORK: A growing number of studies suggest that the night time breathing disorder, sleep apnea, can contribute to a range of cardiovascular diseases, according to researchers from the Mayo Clinic in Rochester, Minnesota.

Writing in the journal Sleep, they detail the evidence linking sleep apnea to high blood pressure, coronary artery disease, stroke, heart failure and heart-rhythm disorders.

The connection between the sleep disorder and heart health is increasingly being recognised, the authors say – both because of recent research, and possibly because sleep apnea is becoming more common.

People with sleep apnea have repeated stops and starts in their breathing as they sleep, sometimes hundreds of times per night. Of the two forms of sleep apnea, obstructive sleep apnea (OSA) is by far the more common; it occurs when the soft tissues at the back of the throat repeatedly collapse during sleep, temporarily cutting off breathing. When this happens, the brain briefly rouses the person from deep sleep to re-open the airways.

Sleep apnea sufferers often don’t remember these awakenings, but some tell-tale signs of the disorder include chronic, loud snoring and daytime drowsiness.

Sleep apnea does more than interrupt a good night’s rest, however. Growing evidence is implicating it as a risk factor for numerous cardiovascular problems, according to the authors of the new report, led by Dr Sean M. Caples.

The short-term consequences of sleep apnea episodes include oxygen deprivation, nervous system activation and changes in pressure within the chest, according to the researchers.

Over time, they explain, these stressors can cause long-term dysfunction in the nervous and cardiovascular systems, ultimately contributing to high blood pressure, heart problems and stroke.

The strongest connection has been seen between OSA and high blood pressure. Repeated episodes of oxygen deprivation seem not only to trigger short-term spikes in blood pressure, the researchers note, but may also lead to chronic blood pressure elevations.—Reuters