Featured Research

from universities, journals, and other organizations

Researchers Shed Light On Snoring, Stroke Risk

Date:
January 13, 1998
Source:
American Heart Association
Summary:
Sleep disorders associated with heavy snoring pose the greater stroke risk, researchers reported in the Jan. 9 issue of Stroke: Journal of the American Heart Association.

DALLAS, Jan. 9 -- Sleep disorders associated with heavy snoring pose the greater stroke risk, researchers reported today in Stroke: Journal of the American Heart Association.

The study by U.S. and German researchers is the first to indicate a possible mechanism for stroke risk that could explain why some sleep disorders are more dangerous than others.

Earlier epidemiological studies had found an increased risk of stroke in people with all apneas and hypopneas. Obstructive apnea causes breathing to stop temporarily; obstructive hypopnea causes dangerously reduced ventilation.

Based on the epidemiological studies, scientists have speculated that the strokes could be caused by high blood pressure or a lack of oxygen, says Nikolaus Netzer, M.D., a visiting professor of pulmonary medicine at Case Western Reserve University and a researcher at the University Hospital at Ulm, Germany. Netzer is co-author of the journal report that looked at physiological changes in the body during individual episodes.

He and his colleagues studied 11 men and one woman, all heavy snorers, treated at the University Hospital in Freiburg, Germany. Most people with these sleep disorders tend to have predominantly obstructive syndrome with just a few central apneas. However, these 12 subjects were chosen because they had a high likelihood of having all the types of apneas and hypopneas, the researchers say.

Five of the 12 subjects also had high blood pressure. The scientists monitored the patients during sleep testing to determine their oxygen levels and the amount of blood flowing to the middle cerebral artery, the brain's major blood source.

They found a significant decline in blood flow to the brain in 76 percent of the obstructive hypopnea episodes (heavy snorers) and 80 percent of the obstructive apneas, but only 14 percent of central apneas.

In the obstructive syndromes, the reduced oxygen flow combined with the obstructions in the airways to create negative pressure in the chest, Netzer says. When the sleepers tried to breathe, the obstructions caused the negative pressure in the chest to increase and monitors indicated a reduced blood flow to the brain. Because of the obstruction, the chest moves to try to breathe in, but the obstruction causes the negative pressure to increase, and this decreases blood flow out of the heart. "It's almost like sucking on a straw," he says. The negative pressure leads to a fall in blood pressure and a fall in blood flow to the brain.

In central apnea, the nervous system does not tell the body to take a breath, so the chest remains still until the end of the episode, the researchers explained.

When the person does breathe, the unobstructed airway creates no negative pressure and, therefore, is less likely to affect blood flow to the brain. "The results were consistent with our hypothesis," Netzer says.

"Earlier papers did not refer to any kind of stroke mechanism; they just reported a close relationship between stroke and sleep apnea syndrome," Netzer says. "Our hypothesis is that the negative thoracic (chest) pressure causes a reduction in blood flow in the middle cerebral artery that may lead to stroke." A vibration of the soft palate and uvula causes all snoring. Mild snoring, or social snoring, poses no health problems, says Kingman P. Strohl, M.D., co-author of the study and director of the Sleep Research Center at Case Western Reserve University in Cleveland. However, in obstructive sleep apnea-hypopnea syndrome, the soft palate and uvula completely (apnea) or partially (hypopnea) block the throat during sleep and cause heavy snoring.

"Heavy snoring with apnea is characterized by loud, resuscitative snores -- or snorts -- after a pause in breathing. It can be heard in the next room," Strohl says. Sufferers wake themselves hundreds of times each night in an effort to get enough oxygen. They get up exhausted and tend to fall asleep at work or while driving. Obstructive sleep disorders affect men more than women and occur most often in moderately or severely overweight people who sleep flat on their backs, although individuals of normal weight also can be affected.

Another sleep disorder, central apnea, occurs when the nervous system's breathing center temporarily stops sending the body instructions to breathe. Heavy snoring is less common in that condition, he says.

Their co-researchers include Peter Werner, M.D., and Isabel Jochums, M.D., both in the division of pulmonary medicine at the University Hospital, Freiberg, Germany; and Manfred Lehmann, M.D., director of Sports Medicine, University Hospital, Ulm, Germany.


Story Source:

The above story is based on materials provided by American Heart Association. Note: Materials may be edited for content and length.


Cite This Page:

American Heart Association. "Researchers Shed Light On Snoring, Stroke Risk." ScienceDaily. ScienceDaily, 13 January 1998. <www.sciencedaily.com/releases/1998/01/980113062625.htm>.
American Heart Association. (1998, January 13). Researchers Shed Light On Snoring, Stroke Risk. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/1998/01/980113062625.htm
American Heart Association. "Researchers Shed Light On Snoring, Stroke Risk." ScienceDaily. www.sciencedaily.com/releases/1998/01/980113062625.htm (accessed July 30, 2014).

Share This




More Health & Medicine News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins