Washington, Feb 13 : A new study conducted by researchers from Imperial College London and other European institutions has found that night-time noise from aircraft or traffic can increase a person's blood pressure even if it does not wake them.
For the study, the researchers monitored 140 sleeping volunteers in their homes near London Heathrow and three other major European airports.
They measured the volunteers' blood pressure remotely at 15-minute intervals and then analysed how this related to the noise recorded in the volunteers' bedrooms.
High blood pressure, defined by World Health Organisation as being 140/90mmHg or more, increases risk of developing heart disease, stroke, kidney disease and dementia.
The authors found that volunteers' blood pressure increased noticeably after they experienced a 'noise event,' a noise louder than 35 decibels, such as aircraft travelling overhead, traffic passing outside, or a partner snoring.
The effect was observed even if the volunteer remained asleep and so was not consciously disturbed.
Noise with the aircraft caused an average increase in systolic blood pressure of 6.2 mmHg and an average increase in diastolic blood pressure of 7.4 mmHg. Similar increases in blood pressure were seen also for other noise sources such as road traffic.
The study showed that the increase in blood pressure was related to the loudness of the noise, so that a greater increase in blood pressure could be seen where the noise level was higher.
For instance, for every 5dB increase in aircraft noise at its loudest point, there was an increase of 0.66 mmHg in systolic blood pressure.
The decibel level, and not the origin of the sound, was responsible for the effect that each noise event had on the volunteers' blood pressure, with similar effects regardless of the type of noise, where the 'loudness' of the noise was the same.
"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," said Dr Lars Jarup, one of the authors of the study from the Department of Epidemiology and Public Health at Imperial College London.
"Our studies show that night-time aircraft noise can affect your blood pressure instantly and increase the risk of hypertension," he added.
The study is published in the European Heart Journal.