Snoring could be more than just a major annoyance to you and your loved ones. It could mean that you are more prone to strokes, as could daytime sleepiness and sleeping longer at night, according to a report by researchers at the American Stroke Association's annual conference in Fort Lauderdale, Fla., this week.

A stroke is when blood flow to or within the brain is reduced or cut off. This decreases the brain's oxygen supply, causing cell damage. If the flow is obstructed for more than a few minutes, brain tissue can die, resulting in permanent disability. What are called transient ischemic attacks are temporary, stroke-like events that last for a short time and usually don't cause a disability. However, they can be signals that you are at risk for a stroke.

The study, in which more than 1,300 adults participated, found that 14% of those who reported sleeping more than eight hours a night, or who experienced frequent sleepiness during the day, had suffered a previous stroke or transient ischemic attacks. This compared with only 5.4% for those who slept less than eight hours a day and those who did not experience daytime drowsiness.

"This points out an important new risk factor for strokes," says researcher Adnan Qureshi, MD, State University of New York at Buffalo assistant professor of neurosurgery.

Qureshi and colleagues had conducted an earlier study using database information. They discovered then that over 10 years, the patients most likely to suffer a stroke or transient ischemic attacks were those who initially reported long sleep periods and drowsiness during the day.

Snoring and trouble staying awake during the day can be signs of a sleep disorder, such as sleep apnea, and such a condition could contribute to stroke or heart disease, Qureshi tells WebMD. "We want patients evaluated for these problems. Physicians should inquire of the patients about these characteristics," he says.

People with sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night and often for a minute or longer, due to various causes, like blockage of the airway, or the brain failing to signal the muscles to breathe.

Qureshi's present study is not the first to link sleep disorders, such as sleep apnea, with stroke.

A 1996 study by University of Iowa Sleep Disorders Center researchers found that 77% of the men and 64% of the women they studied, who had suffered previous strokes, also had obstructive sleep apnea. In a group of people with no major medical problems, only 23% of the men and 14% of the women had sleep apnea.

However, experts caution that snoring is not necessarily related to either sleep disorders or to strokes. During sleep, airway muscles relax. In obstructive sleep apnea, they actually collapse, cutting off oxygen flow.

"This happens multiple times during the night, up to 100 times an hour," says Charles Cantor, MD, neurology consultant for the University of Pennsylvania Center for Sleep Disorders. "Not everyone who snores has sleep apnea. When the muscles in the back of the throat become floppy, they will vibrate, causing snoring. Or they can become so floppy that they cut off oxygen flow."

Cantor says "a fair amount of data" exists to support an association between apnea and stroke.

What that means is that the mechanical cutting of oxygen plays some role in the obstruction of blood flow to the brain but not necessarily that the sleep disorder is a cause of the stroke. However, Cantor says that he personally believes that sleep apnea does place a person at risk for a stroke. That's because it is known that disorders like sleep apnea increase blood pressure, cut off oxygen flow, and change heart function and blood flow.

Eugene Lai, MD, PhD, an associate professor of neurology at Baylor College of Medicine in Houston, says that while sleep apnea does cause reduced oxygen in the brain and can aggravate coronary artery disease, no proof exists of apneas being clear causes of stroke.

"I've seen thousands and thousands of stroke patients, and I've never seen a direct link," he says. "There are a lot of reasons people get sleepy during the day. It's not necessarily sleep apnea."

However, he says those who have sleep apnea should be evaluated by a physician to determine other stroke risk factors, including obesity, diabetes, and hypertension.

Qureshi says he and his team are now trying to determine the underlying mechanisms that appear to link sleep habits with strokes.

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