Noise is a part of everyday life, but too much noise can have a negative impact on your health, leading to an increased risk of hypertension, stroke, heart attack, and more.

Noise may be an 'unrecognized health threat'

According to the New York Times, loud noises, including passing trains, busy city streets, and airplanes flying overhead, are "a largely unrecognized health threat" that can increase the risk of several health conditions.

When you hear a loud or unpleasant noise, the sound is relayed to the amygdala, a part of the brain that is triggered by stress. Over time, if the amygdala is chronically overactivated by noise, it can cause the endocrine system to overreact, leading to too much cortisol, adrenaline, and other chemicals in the body.

The sympathetic nervous system may also become hyperactivated. This leads to a faster heart rate, higher blood pressure, and increased production of inflammatory cells. These changes can then cause hypertension, inflammation, and plaque buildup in the arteries, which then increase the risk of heart disease, heart attacks, and stroke.

In a study of hundreds of patients at Massachusetts General Hospital, researchers found that those who lived in places with high levels of transportation noise were more likely to have a highly activated amygdala, arterial inflammation, and experience a major cardiac event in five years.

In addition, another study found that being exposed to higher levels of aircraft noise in the two hours before a nighttime death was associated with heart-related mortality.

Millions of people live in places that are too loud

According to the World Health Organization (WHO), average road traffic noise that is over 53 decibels (dB) or average aircraft noise that is above roughly 45 dB have been associated with negative health effects. At night, WHO recommends less than 40 dB of noise to avoid adverse effects and less than 30 dB for high-quality sleep.

In the United States, data from the Department of Transportation shows that almost a third of the population, or around 95 million people, live in areas that have noise levels of at least 45 dB.

Even lower levels of noise can be detrimental. For example, a study that followed over 4 million people for more than 10 years found that, starting from 35 dB, the risk of dying from cardiovascular disease increased by 2.9% for every 10 dB increase in road traffic noise.

Aside from the volume of a sound, fluctuations in noise levels can also have a negative impact on health and may be more detrimental that continuous loud noise — even if the average decibel levels are similar.

Loud noises that only occur periodically, such as the passing of a train, often lead to higher degrees of "noise intermittency," or the extent that certain sounds can be distinguished from background noise. And according to a Swiss study, higher degrees of noise intermittency were associated with heart disease, heart attacks, heart failure, and strokes.

How to protect yourself from noise

In general, "noise cannot be addressed fully between a patient and a doctor," the Times writes. "Protection requires changes in local, state and federal policy." However, health experts say that there are still some ways to protect yourself from too much loud noise, including:

• Replacing any old windows with double-pane glass
• Applying foam insulation to noisy rooms, such as laundry rooms
• Sleeping in rooms as far away from the road as possible to reduce nighttime noise
• Investing in heavy window drapes and thick rugs to reduce potential vibration
• Wearing earplugs when necessary

(Baumgaertner et al., New York Times, 6/9; Baumgaertner, New York Times, 6/9)