Florence Nightingale couldn’t sleep. It was 2 a.m. in the military hospital amid the Crimean War, and the noise never stopped. Buckets clanging, shouting, and machinery grinding drowned out the groans of wounded soldiers.

The famous nurse wasn’t troubled by the chaos of war; rather, by something she observed that her colleagues readily dismissed: Patients engulfed by noise simply couldn’t heal.

“Unnecessary noise is the most cruel absence of care which can be inflicted either on sick or well,” she wrote in her 1859 book, “Notes on Nursing: What It Is, and What It Is Not.”

What Nightingale observed more than 160 years ago is now validated by scientific studies. Research confirms that noise, apart from disturbing the peace, injures the body from top to bottom, even if you don’t consciously hear it.

A Crisis Hiding in Plain Sound

We are immersed in noise.

Noise is defined as unwanted sound that has adverse effects on health. The American Public Health Association describes noise as a major public health hazard, estimating that more than 100 million Americans—with children among the most vulnerable—are at risk.

Noise doesn’t just annoy or cause headaches—it steals years of your life. In 2019, Bruitparif, a French nonprofit organization that monitors noise levels, published a report analyzing “noise maps” in Paris. The analysis concluded that an average resident of any of the loudest parts of Paris and its surrounding suburbs loses “more than three healthy life-years” to various health conditions caused or worsened by everyday noise.

Long-term noise exposure is linked to chronic stress and inflammation, which are further linked to many health conditions, including cardiovascular disease and diabetes, Charlie Roscoe, assistant professor in environmental systems and human health at the OHSU-PSU School of Public Health, told The Epoch Times.

How is it that sound waves can have such dramatic health effects?

The Body That Never Rests

The intensity of sound—or its loudness—is measured in decibels (dB). Zero dB is the lowest and faintest sound that people with healthy hearing can detect, such as a soft whisper in a quiet room or near-silence. As decibel levels increase, sounds become progressively louder and more intense.

To give you an idea, a typical conversation measures around 60 dB, while busy road traffic reaches about 80 dB. As sound levels rise above 110 dB, discomfort begins, and pain occurs above 130 dB. Sustained noise above 70 dB can result in gradual hearing loss, while very loud noise above 120 dB can cause immediate hearing loss, according to a report published in the Journal of Clinical Medicine.

The effect of noise ripples across the body through two pathways: direct and indirect via the stress circuitry.

Hearing Loss

The ears are the gateway through which sound enters the body, and the first to be directly affected.

Physiologically, after the invisible waves of sound hit your eardrums, vibrations are transmitted through the middle-ear bones to the cochlea, the snail-shaped spiral structure in the inner ear, in which are present sensory hair cells. These hair cells convert sound vibrations into electrical signals that the brain interprets as recognizable sounds.

During the process, sound vibrations move and rub the inner hair cells, which naturally subjects them to mechanical shearing. Frequent exposure to intense sound can cause physical damage to the inner ear and lead to a temporary hearing shift, Dr. Chandrakiran Channegowda, professor and head of the ear, nose, and throat (ENT) and head and neck surgery department at M.S. Ramaiah Medical College, India, said.

However, prolonged noise exposure can permanently damage these cells and nerves, leading to irreversible hearing loss, he told The Epoch Times.

Ear pain, intolerance to loud noises, a feeling of dullness or fullness in the ear, and tinnitus (ringing in the ears) are some of the first warning signs of hearing loss.

Surprisingly, even if you get used to noise over time, the assault continues.

Brain Health

Your brain continues to respond to noise automatically. “Harmful effects can occur quietly, without people being consciously aware of them,” Omar Hahad, a senior medical scientist at the University Medical Center of the Johannes Gutenberg-University Mainz, told The Epoch Times.

Persistent sound activates the brain’s alarm system, triggering stress pathways and releasing stress hormones into the bloodstream, harming health.

“Environmental noise is more than just an everyday annoyance. It is a biological stressor,” Hahad, who has studied brain health in the context of noise exposure, said.

In the long run, noise is linked to mental health issues, and even a small change in noise levels matters.

An increase of about 3 dB in residential traffic noise—a small but noticeable shift—is associated with a 22 percent higher odds of anxiety and a 17 percent higher odds of depression. When aircraft noise rises by 10 dB, the risk of depression is increased by 12 percent.

Additionally, long-term exposure to road traffic noise is linked to a higher risk of developing Alzheimer’s disease, with the risk particularly higher for those exposed to louder noise at night.

The risk of stroke, cognitive decline, or dementia makes the issue “particularly urgent” because even modest risk increases can add up to a very large burden at the population level, Hahad said.

Heart Health

Your heart health is equally affected by noise.

In 2023, Roscoe estimated an approximately 4 percent increased risk of cardiovascular disease for each increase of roughly 4 dB in both nighttime and daytime noise.

The research is based on a large, relatively healthy population that participated in the 1980s Nurses’ Health Study, she said, and therefore, the risk may be higher in the total U.S. population because people nowadays experience higher levels of noise and various other stressors.

Additionally, a 2025 meta-analysis published in Environment International examined data from 53 studies across 15 countries and found sufficient evidence that long-term exposure to transportation noise increases the risk of heart disease and heart disease-related deaths.

Reproductive Health

When the levels of stress hormone cortisol remain persistently elevated, it can negatively affect reproductive health by downshifting the sexual hormones.

In a 2024 study, researchers examined the effects of long-term noise exposure on fertility. They found noise was associated with a 14 percent higher risk of an infertility diagnosis in women, and a 6 percent higher risk in men.

Evidence also links residential noise exposure to a decrease in birth weight. With every 6 dB increase in traffic noise, babies are expected to weigh about 19 grams less at birth.

If noise can lead to many health conditions, does it follow that contemporary health care centers are quiet?

Hospital Noise

Nightingale’s complaint still rings familiar in today’s health care wards.

A study of a 1,800-bedded hospital recorded maximum sound levels exceeding 80 dB during the day at locations including the emergency department and the entrance gate. At night, levels exceeded 70 dB at the emergency department, the entrance gate, and even in the advanced cardiac center.

“Most alarmingly, the analysis revealed that the highest sound pressure levels were recorded inside ambulance vans,” Ravindra Khaiwal, the lead author of the study and an expert in environment and public health policy, told The Epoch Times.

Khaiwal, a professor at India’s Postgraduate Institute of Medical Education and Research, said that noise pollution in hospitals is “a serious health concern” and not merely a nuisance.

Patients are not the only ones who pay the price, however. Noise invades our everyday lives, from our health to our wallets. The National Bureau of Economic Research estimated that traffic noise alone imposes an annual economic burden of about $110 billion in the United States.

Turning Down the Noise

There isn’t truly “a single safe threshold” below which noise has no effect, according to Hahad.

Even when people close their eyes while sleeping, their ears are open, keeping their brains and stress systems automatically responding to noise.

Protecting the sleep environment is the most crucial step in preventing noise, Hahad said. He suggests keeping bedrooms quieter, improving insulation, or closing windows. To substantially reduce daily noise dose, choose quieter routes or avoid peak traffic times.

The most effective step is to avoid exposure to loud noise in the first place, Channegowda said. He recommends using ear muffs and earplugs to block sound waves, thereby dampening the direct impact of noise. For people who work in noisy environments, or are even temporarily exposed to loud noise, such as when a subway arrives at the station, there’s drilling at a nearby construction site, or a loud police siren rushes by, try covering your ears.

A nutritious diet goes a long way in preventing hearing loss, Channegowda said. Eating vegetables and fruits rich in vitamin B-complex can help protect your auditory nerve and keep your ears healthy, along with having regular checkups with your ENT.

However, experts hold that noise is a public health problem and that solving it should not fall only on individuals. Society needs to “think more holistically than quick-fix solutions,” Roscoe said. Retrofitting cities to support quieter, calmer, more active lifestyles can deliver major health gains, she said.

It’s clear that more than a century and a half after Nightingale’s experience in the noisy Crimean ward, her standards for sincere care and healing still hold.

Research shows that in moments of silence, the brain shifts into the default mode network, activating areas that support rest, reflection, creativity, and repair. In other words, silence shifts your brain from “doing” things to just “being.”

Perhaps it’s time to start focusing on the role of silence in healing and recovery, because silence heals what noise harms.