Key takeaways
- The World Health Organization’s European office warned in 2009 that aircraft noise at night can push up blood pressure even when it doesn’t wake people1.
- WHO’s 2018 guidelines set night limits for outdoor noise: a yearly average below 45 decibels for road traffic, 44 for rail and 40 for aircraft2.
- Large observational studies tie long-term traffic noise to heart disease, and Europe’s environment agency links transport noise to about 4.6 million people with severe sleep disturbance68.
- A review of 38 studies rated the evidence that steady white noise improves sleep as very low quality, and we found no trial of brown noise at all9.
- Earplugs have low-quality support from hospital studies; if you use a sound machine, keep it quiet, far from the bed and on a timer, especially around babies101213.
In 2019, a University of Pennsylvania team led by sleep researcher Mathias Basner reported on people who slept with heart-rate and movement sensors near Philadelphia International Airport5. The Federal Aviation Administration paid for the work5.
Start with ordinary nights. Brief heart-rate surges of three seconds or more can happen over 80 times a night even with no noise at all5. Your body is busier in the dark than it feels.
Noise adds to that. The louder a plane sounded inside the bedroom, the more likely a sleeper was to wake5.
And waking isn’t the only cost. Back in 2009, WHO’s European office warned that night aircraft noise can raise blood pressure in people who sleep right through it1.
That matters if you live near a highway, a rail line, a flight path or a noisy neighbor. Below, we cover how noise reaches a sleeping body, what the science says about white, pink and brown noise, and which cheap fixes have the best support.
Your brain keeps listening, and your heart answers
Sleep doesn’t switch your ears off. Your brain keeps sorting sounds all night, and some of them jolt you toward lighter sleep.
Researchers measure two kinds of reactions. An arousal is a brief jolt toward lighter sleep, often marked by a quick heart-rate rise. An awakening is a real stretch of wakefulness. Basner’s team counted only awakenings of 15 seconds or longer, because the brief jolts are so common even in silence5.
The body can react even when you don’t wake. In sleep labs, single noise events set off brain-wave reactions and changes in blood pressure and heart rate, Germany’s federal environment agency noted in its 2009 summary of the WHO guidelines4.
Those reactions showed up even in people who had lived with noise for a long time, the agency added, a sign that the body never fully gets used to it4. WHO said early-morning flights do the most to raise heart rate1.
Some people carry more risk. WHO named people with chronic illness, older adults, shift workers and children, plus lower-income families who can’t afford quieter neighborhoods1. And unfamiliar sounds hit harder in a strange room, which our travel article covers as the “first-night effect.”
What WHO counts as too loud at night
In 2009, WHO’s European office set a target: outdoor noise averaging no more than 40 decibels across the night, over a year1. That’s a soft sound. WHO likens it to a quiet street in a residential area1.
For countries that can’t get there soon, WHO offered a stepping-stone of 55 decibels4. It compared long-term exposure above 55 decibels to living by a busy street and said it can trigger high blood pressure and heart attacks1.
The German agency’s summary laid out the levels in between4:
- Below 30 decibels: no substantial effects.
- 30 to 40: body movements, awakenings, self-reported sleep trouble and arousals start to show up, but stay moderate.
- 40 to 55: harm becomes clearly measurable across a population.
- Above 55: the risk to the heart and blood vessels rises.
In 2018, WHO updated its advice by noise source. Each night limit below is a strong recommendation, WHO’s firmest grade2.
| Noise source | WHO night limit (outdoor yearly average) | Strength of recommendation |
|---|---|---|
| Road traffic | Below 45 decibels | Strong |
| Railways | Below 44 decibels | Strong |
| Aircraft | Below 40 decibels | Strong |
| Wind turbines | No night limit; evidence too weak | None made |
Those are outdoor numbers, averaged over a year. Your window changes what reaches your pillow. WHO’s 2018 report puts the gap between outside and inside at about 10 decibels with the window open, 15 when it’s tilted or half-open, and about 25 when it’s closed3.
That sets up a trade-off: a closed window blocks noise but also fresh air. WHO itself warned that soundproofing bedroom windows shouldn’t cost you indoor air quality1. Our article on bedroom ventilation covers how to get both.
Night noise and the heart: a strong link, from observational studies
The noise-heart link is no longer a fringe idea. In a 2024 review in the journal Circulation Research, researchers led by cardiologist Thomas Münzel, with Basner among the coauthors, called the evidence “solid” for ischemic heart disease, heart failure and stroke6.
Their explanation starts in the bedroom. Noisy nights end up shorter and choppier, the authors write, and the body answers with a surge of stress hormones and with oxidative stress, a kind of chemical wear on brain cells and blood vessels6. Over the years, they argue, that wear may impair the lining of the arteries, inflame them and push blood pressure up6.
A 2019 review in the German medical journal Deutsches Ärzteblatt, which Münzel coauthored, put rough numbers on it. The risk of coronary heart disease rose about 6% to 8% for each 10-decibel rise in average traffic noise7. In lab studies, simulated night aircraft noise impaired blood vessel function and raised the stress hormone epinephrine, in healthy adults and in people with heart disease7.
Most of this evidence is observational: researchers track people where they live, rather than assigning noise by chance. That matters because loud roads also carry exhaust. In one Danish study, the link between traffic noise and an irregular heartbeat called atrial fibrillation didn’t hold up apart from traffic air pollution7.
Still, health agencies treat the burden as real. Europe’s environment agency reported in June 2025 that more than 1 in 5 Europeans face harmful transport noise, mostly from roads8. Its report page, which took in corrections to several health estimates on March 27, 2026, ties that noise to about 4.6 million people with severe sleep disturbance and about 73,000 early deaths a year8.
Older WHO estimates for western Europe, from 2011, showed which harm costs the most. Sleep disturbance accounted for about 903,000 healthy years of life lost each year, more than any other noise effect3.
White, pink and brown noise: popular, barely tested
Sound machines, fan apps and streaming tracks promise to cover the bumps in the night. The research is thin.
In 2021, Basner and colleagues reviewed 38 studies of steady white noise or similar broadband sound as a sleep aid9. Results ran from better sleep to worse sleep. The team rated the evidence of benefit as “very low” quality, the lowest grade on the scale it used9.
Basner told a medical news site that most of those studies enrolled 10 or fewer people, with a mix of positive, negative and null results10. He didn’t tell people to quit. His advice was to use the lowest volume that works and, if you only need help falling asleep, to set a timer for about 30 minutes10.
He also asked whether a masking sound could hide a smoke alarm or a crying baby, and whether it might add to hearing loss, an idea he said still needs testing10.
Hospital research points the same way. A 2015 Cochrane review of sleep aids in intensive care units found only low-quality evidence that sound masking slightly improved how patients rated their sleep13.
Pink and brown noise sound deeper than white noise’s hiss, more like steady rain or a distant rumble. Brown noise gets plenty of praise online, but we found no published trial of it as a sleep aid. The 2021 review’s verdict on steady background sound is the best guide available.
Lab devices that time brief sound pulses to deep-sleep brain waves, and a 2026 Penn study of steady pink noise, are covered in our article on sleep stages.
Many natural-health traditions start with a simple rule: remove the cause before you cover the symptom. Noise fits that rule. A louder hiss over a barking dog adds sound to your night, while moving the bed, sealing a gap or wearing earplugs takes sound away. Neither approach has strong evidence yet, but taking sound away sidesteps the open questions Basner raised about adding more10.
Sound machines near a crib can get loud
Parents often use sound machines to settle babies. In a 2014 study in Pediatrics, the American Academy of Pediatrics’ journal, researchers turned 14 infant sleep machines up to their maximum and took readings at three distances11.
Every one was louder than 50 decibels at about a foot away, the ceiling hospitals aim for in newborn nurseries11. Three topped 85 decibels; at that level, eight hours of play would exceed workplace noise limits for adults11.
Distance helped, but not enough. Average maximum levels fell from 79 decibels at a foot to 71 at about 3 feet and 63 at about 6.5 feet, Dr. Louis Bell wrote in an NEJM commentary, and all but one machine still beat the nursery limit at the farther distances12.
The study’s authors gave families simple advice, which Bell called prudent12. Keep the machine as far from the baby as you can, and never inside the crib or on its rail. Use the lowest volume, and run it briefly, until the baby is sleeping soundly. Whether these machines harm babies’ hearing is still unknown, Bell noted12.
For the AAP’s broader safe-sleep rules, see our upcoming articles on mattresses and on sharing a sleeping space.
Earplugs and headphones: the cheap fix and its fine print
Earplugs take sound away instead of adding more. Their best test comes from intensive care units, which are loud around the clock.
The 2015 Cochrane review gathered 30 trials with 1,569 ICU patients13. Only three, all testing earplugs, eye masks or both, had data the reviewers could pool13.
In two of them, with 177 patients combined, plugs and masks went with about 45% fewer cases of delirium, a sudden state of confusion common in the ICU13.
The reviewers rated that evidence low quality, most earplug and mask studies found no benefit on measured sleep, and the trials didn’t clearly report side effects13. Our travel article covers a separate small lab test.
A plug only works if it seals. The National Institute for Occupational Safety and Health (NIOSH), part of CDC, teaches foam-plug users a method it calls roll-pull-hold14:
- Wash your hands, then roll the foam into a slim tube14.
- With your other hand, draw the top of your ear up and back to straighten the canal14.
- Slide the plug in and hold it until the foam swells to fill the canal14.
- Test the seal by cupping your hands over your ears. If sounds get much more muffled, take the plug out and try again14.
Make sure you can still hear your smoke alarm with them in.
Headphones in bed bring a different risk: too much volume, right at your ear, for hours. WHO’s guidelines strongly urge action to keep leisure noise, including sound from personal listening devices, below its guideline levels2. For comparison, the recommended adult workplace limit in the United States and Canada is 85 decibels over eight hours12. Keep sleep audio soft and use a timer10.
Your night noise audit
Before you buy anything, find out what’s waking you. For three nights, jot down any sound you hear as you drift off or when you wake, the time and how you felt the next day. A free sound-meter app can give a rough reading.
Then match each noise to a fix, free ones first.
| Noise | When it tends to hit | Try first | Cost |
|---|---|---|---|
| Street traffic | Rush hours, early morning | Sleep on the quiet side of the home1; move the bed away from the street-side window | Free |
| Aircraft | Early-morning flights, which WHO links to the biggest heart-rate rises1 | Close the window on loud nights3; wear well-fitted earplugs14 | Low |
| Neighbors or hallway | Late evening | Earplugs; a door draft stopper; a rug on hard floors | Low |
| Partner’s snoring | All night | Earplugs; a second room on bad nights; report gasping or choking to a clinician15 | Free to low |
| Fridge, furnace or fan hum | Cycles all night | Close the bedroom door; fix rattles; turn off what you don’t need | Free |
| Phone or smart speaker | Random pings | Do-not-disturb mode; move it out of reach | Free |
| TV or sound machine left on | All night | Set a sleep timer10 | Free |
| Constant outside noise | Every night | Acoustic window upgrades; see our upcoming article on urban sleep | High |
What the evidence supports
| Claim | Evidence level | What the research shows |
|---|---|---|
| Night traffic and aircraft noise disturb sleep | Field and lab studies; WHO issued strong night limits245 | |
| Long-term road traffic noise is linked to more heart disease | Consistent links in many large observational studies and reviews; trials can’t test cause, and air pollution may explain part of some links67 | |
| Steady white noise improves sleep | 38 small, mixed studies rated very low quality910 | |
| Brown noise improves sleep | No published trials found | |
| Sound masking helps hospital patients rate their sleep better | Small improvements, low-quality evidence13 | |
| Earplugs or eye masks lower delirium risk in the ICU | Fewer delirium cases in two pooled studies; measured sleep mostly unchanged13 | |
| Infant sound machines at full volume near a crib stay within nursery noise limits | All 14 machines exceeded 50 decibels at a foot away1112 |
When noise isn’t the whole story
Sometimes quieting the room doesn’t fix the night. MedlinePlus, the National Library of Medicine’s health site, lists signs that may point to a sleep disorder15. Talk with a clinician if you notice any of these:
- You regularly take more than 30 minutes to fall asleep15.
- You often wake several times and struggle to get back to sleep, or wake too early15.
- You often feel sleepy during the day, take frequent naps or doze off at the wrong times15.
- Your bed partner says you snore loudly, snort, gasp or make choking sounds15.
- You have creeping or tingling feelings in your legs or arms that ease when you move or rub them15.
If the noise is a partner’s snoring, that snoring may be a health clue for them. Our upcoming articles on sharing a bed, sleep apnea and medical evaluation cover next steps.
Questions readers ask
Will I get used to the noise?
Partly, maybe. Near the Philadelphia airport, sleepers’ overall sleep fragmentation didn’t differ significantly from that of people in quieter areas, and the authors suggested people may make up for flight wakings between flights5. But sleep labs see heart and blood pressure reactions even in long-time residents of noisy areas4, so sleeping through it doesn’t prove your body has tuned it out.
Is brown noise better than white noise?
No one has tested that, as far as we could find. The 2021 review of steady background sound found only very low-quality evidence of any sleep benefit9. If you like brown noise, keep it soft and on a timer10.
How loud is too loud for a sound machine?
For babies, the 50-decibel hospital nursery limit is a useful ceiling, and most machines tested beat it even at about 6.5 feet1112. For adults, use the lowest volume that masks the sound you’re trying to hide10.
The bottom line
Your ears stand watch all night, and your heart reacts to sounds you never remember. That’s why WHO sets night limits, and why years of traffic noise show up in heart-disease statistics, even though most of that evidence is observational.
The fixes with the best support are the humble ones: sleep away from the noise, close the window when it’s loud, and try a well-fitted pair of earplugs. Sound machines may comfort you, but their evidence is very weak, so keep them low, distant and on a timer, and give babies’ ears extra room.
Related reading
About this article
This article was researched using World Health Organization guidelines, European, German and U.S. government agency materials, a Cochrane review and other peer-reviewed studies, listed below, and was reviewed in October 2026. It is general education, not medical, legal or financial advice..
Sources
- World Health Organization Regional Office for Europe. “One in five Europeans is regularly exposed to sound levels at night that could significantly damage health.” Press release, October 8, 2009 (WHO Europe site copy).
- World Health Organization Regional Office for Europe. “Environmental Noise Guidelines for the European Region: Executive Summary.” WHO, 2018 (WHO Europe site copy).
- World Health Organization Regional Office for Europe. “Environmental Noise Guidelines for the European Region” (full report). WHO, 2018 (copy hosted by Bruitparif). www-preview.bruitparif.fr
- Umweltbundesamt (German Environment Agency). “WHO-Leitlinien für nächtlichen Lärm” (summary of the WHO Night Noise Guidelines for Europe). telegramm: umwelt+gesundheit, Ausgabe 06/2009, October 9, 2009. umweltbundesamt.de
- Basner M, Witte M, McGuire S. “Aircraft Noise Effects on Sleep—Results of a Pilot Study Near Philadelphia International Airport.” International Journal of Environmental Research and Public Health, 2019;16:3178 (U.S. DOT repository copy). rosap.ntl.bts.gov
- Münzel T, Molitor M, Kuntic M, Hahad O, Röösli M, Engelmann N, Basner M, Daiber A, Sørensen M. “Transportation Noise Pollution and Cardiovascular Health.” Circulation Research, 2024;134(9):1113–1135 (Roskilde University research record). forskning.ruc.dk
- Hahad O, Kröller-Schön S, Daiber A, Münzel T. “The Cardiovascular Effects of Noise.” Deutsches Ärzteblatt International, 2019;116:245–250 (author copy). researchgate.net
- European Environment Agency. “Environmental noise in Europe 2025.” EEA Report 05/2025, June 24, 2025 (corrigendum incorporated March 27, 2026). eea.europa.eu
- Riedy SM, Smith MG, Rocha S, Basner M. “Noise as a sleep aid: A systematic review.” Sleep Medicine Reviews, 2021;55:101385 (EM-Consulte abstract). em-consulte.com
- Neurology Learning Network. “Systematic Review Cautions Against Promoting White Noise Machines as a Viable Sleep Aid.” Q&A with Mathias Basner, HMP Global. hmpgloballearningnetwork.com
- Hugh SC, Wolter NE, Propst EJ, Gordon KA, Cushing SL, Papsin BC. “Infant Sleep Machines and Hazardous Sound Pressure Levels.” Pediatrics, 2014;133(4):677–681 (McMaster University record). experts.mcmaster.ca
- Bell LM. Commentary on “Infant Sleep Machines and Hazardous Sound Pressure Levels.” NEJM Clinician (NEJM Journal Watch), 2014. clinician.nejm.org
- Hu RF, Jiang XY, Chen J, et al. “Non-pharmacological interventions for sleep promotion in the intensive care unit.” Cochrane Database of Systematic Reviews, 2015, Issue 10, CD008808 (abstract; edited 2018, conclusions unchanged). cochranelibrary.com
- National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention. “How to Wear Soft Foam Earplugs.” CDC, June 29, 2026. cdc.gov
- MedlinePlus. “Sleep Disorders.” National Library of Medicine, updated December 4, 2025. medlineplus.gov