Sleep, once considered the time for restoration and recuperation, is under assault from noise pollution. New research has revealed that any 'noise event' above 35 decibels causes an increase in blood pressure, even when the person is asleep.
Five thousand volunteers living near major European airports had their blood pressure remotely monitored every 15 minutes while they slept. The results revealed that an increase in aircraft noise of 10 decibels increased the risk of high blood pressure by 14 per cent in both men and women. For every 5 decibels above the threshold of 35 decibels, blood pressure increased by 0.66 mmHg (blood pressure is measured in millimetres (mm) of mercury (Hg)).
Dr Lars Jarup Noise pollution has been linked with heart attack and strokes because it keeps the body in a state of alert and causes chronic stress. Noise pollution from traffic or even a partner snoring can have the same effect.
Dr Lars Jarup, a lead researcher from Imperial College London, UK, stated:
"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."
Previous research by the team has shown that people who have been living for at least five years near an international airport, under a flight path, have an increased risk of high blood pressure.
"our studies show that night-time aircraft noise can affect blood pressure instantly . . this is surprising, since such an immediate effect from noise events has never been shown", said Jarup.
Noise pollution is a significant stressor for many people. The World Health Organisation (WHO) estimates that long-term exposure to traffic noise could account for around 3 per cent of deaths from heart disease and strokes. Even when we sleep our bodies continue to react to sound and this increases the levels of stress hormones.
Dr Rokho Kim, of the WHO/Euro Centre for Environment & Health, has related sleep disturbance with an increase in the number of accidents. Sleeping fewer than 5 hours per night increases the risk of accident 4.5 times. Kim also attributes aircraft noise to impairments in reading comprehension and recognition memory.
Although the WHO have yet to agree on the precise levels of chronic exposure to noise with cardiovascular problems, the levels currently suggested point to a night-time level of 50 decibels and a daytime exposure above 60 decibels. In Europe, cities with populations over 250,000 will soon be required to produce noise maps revealing the places where noise is greatest.