“Do you hear that?” asked Mathias Basner, MD, PhD, who then let a few moments pass. “Do you know what that is?”

He paused again.

“Silence. The sound of silence.”

Basner posed the rhetorical question at his TEDMED talk, the health and medicine offshoot of the TED conference series, last year in Palm Springs, Calif., to break the ice. But he was also trying to make a point.

Silence is a rare commodity these days, he continued, because society has only gotten louder. There are more cities housing more people, more buildings rising in skylines, and more trains, cars, and airplanes zipping around than ever before, amping up the decibels in communities around the globe.

“And we're all paying a price for it in terms of our health,” said Basner, an associate professor of Sleep and Chronobiology in Psychiatry at Penn. “A surprisingly big price, as it turns out.”

Loud noises can damage hearing, but there are lesser-known and equally dangerous impacts on the rest of the body.

People respond to unwanted sounds by excreting stress hormones like adrenaline and cortisol that can increase blood sugar and pressure and heart rate. Experience too much of it over extended periods of time and it increases the risk of cardiovascular disease and heart attacks, among other health issues, epidemiological studies and experts have suggested.

Sleep disturbance—the focus of Basner’s research—is another underrecognized consequence of excessive noise. 

During sleep, people’s eyes stay shut, but their ears are open, and their brain is listening, monitoring for threats in the environment. They’re exposed. A honk from a car or an airplane swooshing by could wake a person up without them even knowing it and interrupt a good rest several times during the night. That, just like a sleep disorder, can cause problems in the future. Disruptions in sleep from noise have been tied to cardiovascular problems, mood disorders, cognitive decline, lower productivity, and an overall reduced quality of life.

“We are in a vulnerable phase when we are sleeping,” he said. “We are not really aware of ourselves and our surroundings, so we are an easy prey.”

Noisy Nights

The effect of noise is one of the three pillars of Basner’s research, and the relationship between transportation noise and sleep has been central to that work since his career began at the German Aerospace Center in the late 1990s.

Basner’s first study looked at aircraft noise emanating from the Cologne Airport, a busy freight hub at night, and the impact it was having on the people living nearby. The team used data from a combination of sleep lab and field studies with nearly 200 adults to determine the probability of awakenings from the aircraft noise, which were later used to establish newer noise criteria for several airports. But they also found that people’s cortisol levels were being affected. The louder it got, the higher they shot up.

By the mid-2000s, Basner and his colleagues had expanded their work to include the impact of car and railway traffic noise on sleep—and it revealed a few surprises. While surveys typically point to aircraft as the most annoying to residents, that’s not what appears to cause the most disruptions in their sleep.

In a study in the journal Sleep in 2011, the researchers reported that road and rail traffic noise led to stronger disruptions of sleep than airplanes, even though people still reported to be most annoyed by aircraft noise in the morning. Many times, research participants felt like they had slept like a baby, unaware of being woken up multiple times by the noise events.

“We know that there are differences in how people perceive noise or how annoyed they are by the different noises, so we wanted to see if we could also observe these differences in their reactions while sleeping,” Basner said. “And we found that…at the same noise level, people react to aircraft noise to a much lesser degree.”

This was recently confirmed in meta-analysis published earlier this year from Basner and his colleagues in the International Journal of Environmental Research and Public Health.

“This is why we are very much in favor of also considering physiological criteria to determine how a specific noise source affects sleep,” Basner said.

Rethinking Noise Standards

Today in the United States, there are no federal noise standards.

State and local governments are primarily responsible for any regulations, outside of noise pertaining to road, railways, and airports, which fall to the Federal Aviation Administration (FAA) and Federal Highway Administration (FHA). Those regulations have historically been guided by noise modeling programs, environmental impact statements, and annoyance surveys.

For years, though, noise experts, researchers and residents affected by noise have been pushing for the federal government and its agencies to establish new criteria and consider more research data to develop them.

The other side of the pond has been more progressive about this. Basner’s first sleep study was sanctioned by the DLR-Institute of Aerospace Medicine in Germany to develop recommendations for revised protections against excessive noise in the German Aircraft Noise Protection Act. Data from that five-year study was later used to establish noise criteria for an expansion of the Leipzig/Halle airport. It’s these type of studies that can help redefine appropriate sound levels, as well as inform insulation efforts to muffle noise.

In another sign of supporting change, in the European Union’s Environment Action Program, the EU committed to significantly decrease noise pollution, moving closer to levels recommended by the WHO by 2020.

The United States was actually one of the first nations to appreciate the impact of noise pollution. It passed the Noise Control Act of 1972 and opened the Office of Noise Abatement and Control to study noise, but in the early 1980s that office and funding was eliminated, so efforts dried up.

It wasn’t until relatively recently America started focusing again more closely on noise research, said Basner, who is currently funded by the FAA to study noise effects on sleep at airports across the country. He and other researchers are working to better understand the impact of noise on health and sleep for the purposes of potentially revising noise criteria to ensure the levels are protective enough.

“I’m hopeful the awareness of noise as a public health problem is increasing,” Basner said. “And that agencies like the National Institutes of Health will fund more noise effects research to inform better standards, regulations, and policies to make safer environments.”

Try This at Home

In the meantime, Basner said people can take their own steps to reduce exposure to noise.

If a place is too loud, say something. Move a bedroom to a quieter part of the house, if possible. When looking to buy or rent, visit the place at different hours of the day and listen. Wear noise-canceling headphones.

Make low noise a priority, he said.

“In general, seek out quiet spaces, especially on the weekend or when you're on vacation,” Basner said during his TEDMED talk that day. “Allow your system to wind down.”