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Researchers compiled data from the famous Sleep Heart Health Study and looked at stroke risk in 5,422 participants aged 40 years and older without a history of stroke. At the start of the study, participants performed a standard at-home sleep test that determined whether they had sleep apnea and, if so, the severity of the sleep apnea. Participants were followed for an average of nine years. During that period, a total of 193 participants had a stroke - 85 men (of 2,462 men enrolled) and 108 women (out of 2,960 enrolled).
Study investigators found that the increased risk of stroke appeared in men with mild sleep apnea. Their risk of stroke rose if the apnea was more severe. Men with moderate to severe sleep apnea were nearly three times more likely to have a stroke than men without sleep apnea or with mild sleep apnea. But in women it was different. The increased risk of stroke in females was significant only with severe levels of sleep apnea. The increased risk of stroke from sleep apnea depended on other risk factors the women had such as weight issues, smoking, race, diabetes and high blood pressure.
People who have sleep apnea can have one or more pauses in breathing or shallow breaths while they sleep. It can also be accompanied with loud snoring, or snorting. The pauses often occur five to 30 times an hour. Many times the sleeper is disrupted during the night, because of odd breathing habits, which can result in excessive daytime sleepiness. The erratic sleeping/breathing pattern can also put serious stress on the heart, because the pauses cause the flow of oxygen to the vital organs to slow or even stop for a few seconds, which makes the heart pump harder.
"And what's even more alarming, is that the body becomes used to these erratic patterns, even if we are not sleeping," says Michael J. Twery, Ph.D., director of the NIH National Center on Sleep Disorders Research "And when that happens you have stress on the heart all the time. The effects from sleep apnea start to erode your health and that can eventually lead to stroke."
Researchers believed that because men are more prone to have sleep apnea earlier in life, the risks of stroke are much higher than in women, who usually suffer from sleep apnea when they are pregnant, overweight or are already going through menopause.
"So it suggests, that the longer you have sleep apnea, the more at risk you are," notes Twery. "And men just seem to develop it at an earlier age."
"Our findings provide compelling evidence that obstructive sleep apnea is a risk factor for stroke, especially in men," said Susan Redline, M.D., M.P.H., professor of medicine, pediatrics, and epidemiology and biostatistics, at Case Western Reserve University in Cleveland, Ohio, and lead author of the paper. "Overall, the increased risk of stroke in men with sleep apnea is comparable to adding 10 years to a man's age. Importantly, we found that increased stroke risk in men occurs even with relatively mild levels of sleep apnea."
Because sleep apnea symptoms happen at night, when the patient is asleep, many don't realize they are affected and can go years, even a lifetime, suffering from the condition and not knowing it.
So how do you know if you have sleep apnea, or just a snoring problem? Sleep experts recommend that if you have a partner who notices you are snoring heavily and gasping for breath as you sleep, or you wake up in the morning and find you can't function during the day, because you a sleepy, it's best to talk to you doctor. Prior studies have shown that sleep apnea can be a precursor to hypertension, weight gain, diabetes, as well as heart disease and stroke. It is also linked to excessive daytime sleepiness, which lowers performance in the workplace and at school, and increases the risk of injuries and death from drowsy driving and other accidents.
"It's really up to the patient to make the first move, to go to the doctor and ask to be tested." explains Twery, "There are a lot of treatments out there that can help. And people need to follow them. Because sleep apnea has no pain with it, many people think it can't hurt them. But research shows, that sleep apnea can and will hurt your body, especially if it goes undetected."
The next step for this project? Researchers will start clinical trial studies that can help scientists determine if treating sleep apnea can lower a person's risk of stroke and other diseases.
