In fact, the louder the noise, the higher blood pressure will go, the study found. That finding holds whether the noise comes from airplanes, passing traffic or other sources, according to the report in the February issue of theEuropean Heart Journal.

"We know that noise from air traffic can be a source of irritation, but our research shows that it can also be damaging for people''s health, which is particularly significant in light of plans to expand international airports," co-author Dr. Lars Jarup, from the Department of Epidemiology and Public Health at Imperial College London, said in a prepared statement.

"Nighttime aircraft noise can affect your blood pressure instantly and increase the risk of hypertension. It is clear to me that measures need to be taken to reduce noise levels from aircraft, in particular during nighttime, in order to protect the health of people living near airports," Jarup said.

In the study, the British team studied 140 people who lived near London''s Heathrow Airport, as well as airports in Athens, Milan and Stockholm.

While the volunteers slept, the researchers remotely measured their blood pressure every 15 minutes. They also analyzed the noise level in the participant''s bedrooms.

Jarup''s group found a noticeable increase in blood pressure when noise levels grew louder than 35 decibels. That amount of increased noise can occur as an airplane flies overhead, from traffic noise, or even from someone snoring nearby. The increase in blood pressure was apparent even when the participant stayed asleep, the researchers found.

The noise from aircraft increased blood systolic pressure (the top number in a reading) an average of 6.2 mmHg, and diastolic pressure an average of 7.4 mmHg, the researchers found. This increase in blood pressure was also seen from other noise, such as road traffic, according to the report.

The boost in blood pressure was directly related to the loudness of the noise, Jarup''s group found. In fact, every 5 decibel increase in airplane noise caused an increase in systolic blood pressure of 0.66 mmHg. The key factor in increasing blood pressure was the level of the noise, not its source, the researchers noted.

One expert believes more studies are needed to see if avoiding noise can benefit cardiovascular health.

"Elevations in systolic and diastolic blood pressure are important modifiable risk factors for heart attack and stroke," said Dr. Gregg C. Fonarow, a professor of cardiology, at the University of California, Los Angeles.

This study is consistent with earlier studies, which showed that environmental noise can significantly increase systolic and diastolic blood pressure during sleep, Fonarow added.

"Further studies are necessary to determine if avoiding excess noise during sleep will result in better blood pressure control and cardiovascular risk reduction in individuals with hypertension," Fonarow said.

"The study adds to the literature that noxious and stressful exposures have adverse cardiovascular consequences," said Dr. Harlan M. Krumholz, a professor of medicine at Yale University School of Medicine in New Haven, Conn.

How this finding translates into policy is not quite clear, but it appears that the adverse effect of noise can be demonstrated by blood pressure changes, Krumholz said. "What is interesting here is that it occurred during sleep," he added.

"Whether all people are affected similarly and whether this response correlates with a higher risk of heart disease is not clear, but it seems sensible to assume that a noisy environment is not good for health," Krumholz said.

More information

For more on high blood pressure, visit the American Heart Association.

SOURCES: Harlan M. Krumholz, M.D., professor, medicine, Yale University School of Medicine, New Haven, Conn; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; February 2008European Heart Journal