Noise and sleep: what the research says

Updated 10 November 2026

Modeled estimates for general information only — not measurements, not a guarantee, and not for legal, medical or real-estate decisions.

Published research says traffic noise can affect sleep. A 2018 review of 74 studies, done for the WHO’s noise guidelines, found that road, rail and aircraft noise affects both sleep measured in studies and the sleep disturbance people report (Basner and McGuire, International Journal of Environmental Research and Public Health, 2018). Other research finds that the sleeping brain keeps registering sounds, and that the body can react without waking.

Each finding below names its study and links to it. The numbers describe groups of people in those studies, mostly in Europe. They don’t say what a noise level means for one person, and this page is not medical advice.

Does the brain hear sounds while you sleep?

Your brain keeps listening at night. A review of the research on noise and the heart says we “recognize, evaluate, and react to environmental sounds even while asleep” (Münzel et al., European Heart Journal, 2014, a review). A sound doesn’t have to wake you to have an effect: the body’s reaction is not all or nothing.

Can noise affect you without waking you?

In sleep studies, it can. Your heart rate and blood pressure can rise with noise, without waking you. The same review calls these “vegetative arousals”: short rises in blood pressure and heart rate during sleep (Münzel et al., 2014).

Do you get used to noise at night?

Only partly. You get used to the noise; your body doesn’t, not completely. The same review says getting used to it, which researchers call habituation, is not complete: people kept reacting even after several years, and the heart-rate and blood-pressure reactions adapt much less than waking up does (Münzel et al., 2014).

Does louder noise wake you more often?

In sleep studies, the odds of waking rose by about a third for every 10 dB louder indoor peak of a noise event (Basner and McGuire, International Journal of Environmental Research and Public Health, 2018, a systematic review for the WHO). The pooled odds ratios were 1.35 for aircraft, 1.36 for road and 1.35 for rail noise. A peak is the loudest moment of one passing car, train or plane, measured indoors. It is a different measure from the map’s outdoor averages.

Does a quieter side of the home matter?

In a Danish study of 2.9 million adults, homes with a quieter side were linked with lower depression risk (Kirkegaard et al., The Lancet Regional Health – Europe, 2026, an observational cohort). It is a link, not proof of cause, and the study was in Denmark.

What does the WHO recommend for noise at night?

The WHO’s 2018 noise guidelines for Europe (WHO Regional Office for Europe, 2018) recommend keeping road traffic noise at night below 45 dB (Lnight, an outdoor yearly average). A benchmark for populations, not a safe or unsafe line for one person.

By our model, about 8 in 10 LA County buildings have a wall where road noise at night averages 45 dB or more. It’s a county-wide count by each building’s loudest wall, with road noise only, and not a reading for a single address. Buildings include garages and sheds, so this isn’t a count of homes or people. Our night (10 pm to 7 am) and the WHO’s Lnight (usually 11 pm to 7 am) are close but not the same measure. How we counted, and the limits: How it’s made.

What the Quiet LA map shows at night

Quiet LA is a free map of modeled outdoor noise in Los Angeles County. Look up an address in LA County and see its modeled night level; the Night view covers 10 pm to 7 am. Compare the street side with the back: tap a building to see its loudest and its least exposed wall, or switch to Dots to see each wall. Then look around for the pockets of calm nearby.

Look up an address

This page sums up published research for general information and is not medical advice. The map’s levels are modeled estimates. How they are made: How it’s made and Limits.