The short answer
The World Health Organization's bedroom guideline is 30 dB averaged over the night for steady noise, with single noises kept under 45 dB at their peak (WHO, 1999). Field studies find extra awakenings from single noises starting at about 33 to 38 dB indoors (Basner and McGuire, 2018). Newer WHO night targets of 40 to 45 dB are measured outside the house, where a closed window cut noise by a median of 28 dB in one field study (Locher et al., 2018).
This guide is for: people who want the published night-time noise figures for a bedroom in decibels, and a plain way to tell average sound from peak sound.
Key Takeaways
Three figures carry most of what the published research says about night noise in a bedroom, and two of the three are measured inside the room.
- 30 dB average, 45 dB peak: to avoid sleep disturbance, the WHO's indoor guideline values for bedrooms are 30 dB LAeq for continuous noise and 45 dB LAmax for single sound events (WHO, 1999).
- 33 to 38 dB: a review of road, rail and aircraft studies found extra awakenings begin when single noises peak at 33 to 38 dBA indoors (Basner and McGuire, 2018).
- 40 to 45 dB outside: the WHO's 2009 and 2018 night targets are measured outside the house, not at the pillow (Noise and Health, 2010; WHO compendium, 2022).
What decibel level do health agencies publish for a bedroom at night?
The WHO's bedroom figure is 30 dB averaged over the night and 45 dB for any single noise, and both are measured inside the room.
The figure quoted most often comes from the World Health Organization's Guidelines for Community Noise, published in 1999. It sets 30 dB for the night's average and 45 dB for any single event inside a bedroom (WHO, 1999). The WHO page explains the average figure: measurable effects on sleep start when background noise reaches about 30 dB.
The guideline also covers people who sleep with a window open. Outside the bedroom wall, it gives 45 dB as the night average and 60 dB as the peak (WHO, 1999).
The WHO also allows for sensitive sleepers. Its summary says that for them, a lower limit is preferred (WHO, 1999 summary). That matters if you are checking a room for someone who wakes easily.
| Source | Where it applies | Average or peak | Figure |
|---|---|---|---|
| WHO, 1999 | Inside the bedroom | Average over 8 hours | 30 dB LAeq |
| WHO, 1999 | Inside the bedroom | Single-event peak | 45 dB LAmax |
| WHO, 1999 | Outside the bedroom window | Average, then peak | 45 dB LAeq, 60 dB LAmax |
| WHO 2018 figures, via WHO compendium, 2022 | Outside the house | Night average | Road 45, rail 44, aircraft 40 dB Lnight |
| EPA, 1974; HUD, 24 CFR 51.101 | Inside the home | 24-hour day-night average | 45 dB Ldn |
What is the difference between average and peak noise at night?
An average spreads all the night's sound over eight hours, while a peak is the loudest moment, and a quiet average can hide a waking noise.
Most published limits use one of two measures. Mixing them up is the most common way to misread a bedroom. The average, written LAeq or Lnight, is the steady level that carries as much total sound energy as everything heard over the night. The peak, written LAmax, is the loudest instant of a single noise, such as a door closing or a truck passing.
Two rooms with matching averages can sleep differently. The WHO's night guidelines note that a 40 dB average can describe two different nights, depending on whether the noise comes in bursts or runs steadily (Noise and Health, 2010). A fan that runs all night and a quiet street broken by a few motorbikes might share an average. Only the motorbikes are likely to wake you.
That is why the 1999 guideline pairs its average with a peak. It says guidelines should be written as an average, as a peak, and as the number of noise events (WHO, 1999).
If you log a night with a meter or a phone app, record both the average and the peaks. An average alone will not show the noise that woke you. The noise room check sets out how to take that reading at night.
How quiet is 30 decibels compared with everyday sounds?
Thirty decibels is about a soft whisper heard from 3 feet away, so the WHO bedroom average asks for a room near whisper level all night.
Thirty decibels is quieter than most people picture. A feature in Environmental Health Perspectives puts a soft whisper heard from 3 feet at 30 dBA (Environmental Health Perspectives). So the WHO bedroom average asks for a room whose sound, spread across the whole night, sits near whisper level.
The decibel scale is logarithmic. Each small step on a meter stands for a larger change in sound energy than it looks, so a few decibels at night deserve attention.
Ordinary bedrooms land close to the figure. The EPA estimated that in a typical neighborhood with an outdoor Ldn of 55 dB, the indoor level at night is about 32 dB (EPA, 1974). That puts a quiet residential street within a few decibels of the WHO average before anything inside the room is switched on.
Steady sound you add on purpose counts too. A fan or sound machine raises the average even while it masks the peaks above it. The white noise guide covers how loud to set one so the trade stays worth making.
At what decibel level does a single noise start to wake people?
Field studies find extra awakenings start when a single noise peaks at about 33 to 38 dB indoors, though the odds at that level are small.
Sleep researchers answer this with brain and heart recordings taken during real nights. A review of road, rail and aircraft studies for the WHO found that extra awakenings began when single noises peaked at 33 to 38 dBA, depending on the type of traffic (Basner and McGuire, 2018).
The WHO's night guidelines go lower for smaller reactions. They report that brain-wave arousals and body movements can be seen from peaks as low as 32 dB (Noise and Health, 2010). Those reactions are brief. A sleeper may never remember them in the morning.
This threshold marks the point where some people start to react to a noise. Most people at that level do not, which is why it sits below the published limit.
Read together, the studies place the first reactions to a single noise in the low 30s, under the WHO's 45 dB single-event figure (WHO, 1999). You can treat 45 as the published line and the low 30s as the level where a light sleeper may begin to stir.
Why are many night noise limits measured outside the house?
Newer WHO figures are long-term averages at the outside wall, built for planning roads and airports, so they cannot be checked at your pillow.
The WHO's later guidance changed where it measures. Its 2009 night guidelines set 40 dB Lnight as the target, with 55 dB as an interim target for countries that cannot reach it soon (Noise and Health, 2010). The 2018 guidelines split the figure by source: 45 dB for road traffic, 44 dB for rail and 40 dB for aircraft (WHO compendium, 2022).
The night guidelines define their figure as Lnight outside the building (Night Noise Guidelines abstract). They exist to plan roads and flight paths. So one night with a meter at your bed cannot confirm or break one.
Our count: On November 11, 2026, we read 9 published pages that set a noise figure for homes at night, all from health, environment or housing agencies or archived copies of their guidance. We sorted each page by where its figure applies.
- Inside the bedroom at night: 3 pages. The WHO's 1999 guideline values, its 1999 summary, and its 1995 community noise document as archived by the Noise Pollution Clearinghouse.
- Outside the building only: 3 pages. The PubMed abstract of the WHO's 2009 night guidelines, the WHO compendium chapter on noise, and the European Environment Agency's exposure indicator.
- Only a 24-hour day-night average: 3 pages. The EPA's 1974 Levels Document, HUD's rule at 24 CFR 51.101, and HUD's noise abatement page.
Only 3 of the 9 gave a night figure you could check at the pillow, and all 3 trace back to the WHO's 1999 work.
How much does a closed window lower the noise in a bedroom?
In one field study a closed window cut outdoor noise by a median of 28 dB, a tilted window by 16 dB and an open window by only 10 dB.
The gap between an outdoor figure and your bedroom depends mostly on the window. A field study that recorded sound outside and inside each home found median drops of 10.0 dB with the window open, 15.8 dB tilted and 27.8 dB closed (Locher et al., 2018). Windows without gaskets, the rubber seals around the frame, let through about 2.4 dB more.
The WHO's 1999 figures build in a window too. Its two night averages, 45 dB outside the bedroom window and 30 dB inside, only line up if the window removes the difference (WHO, 1999). The study's median for a tilted window comes close to that gap.
The table subtracts each measured median from the WHO's 45 dB outdoor night average (WHO, 1999). That subtraction is our arithmetic on the study's rounded medians, not a reading from any room.
| Window position | Median reduction, outdoor to indoor (Locher et al., 2018) | A 45 dB night outside (WHO, 1999) becomes about |
|---|---|---|
| Open | 10 dB | 35 dB |
| Tilted (hinged open a few inches at the top) | 16 dB | 29 dB |
| Closed | 28 dB | 17 dB |
Closing the window gets most rooms under the WHO average. It also holds in warm, stale air. The guide to ventilating a bedroom in winter covers that trade-off.
What do United States agencies publish for noise inside a home?
The EPA and HUD both use 45 dB as a 24-hour day-night average indoors, a figure the EPA built around speech and annoyance, not sleep.
Two federal agencies publish indoor noise figures for homes. Both use a 24-hour measure rather than a night-only one. The EPA named 45 dB Ldn indoors and 55 dB outdoors in residential areas as the levels below which speech and other activities go undisturbed (EPA, 1974).
HUD adopted 45 dB too, for housing it funds. It is a HUD goal that the interior auditory environment shall not exceed a day-night average sound level of 45 decibels, and emphasis shall be given to noise sensitive interior spaces such as bedrooms (24 CFR 51.101). Outside, sites whose community noise exposure exceeds a day night average sound level of 65 decibels are considered noise-impacted (HUD Exchange).
It is not a night figure. The day-night average adds 10 dB to sound heard at night and then averages the full 24 hours (EPA, 1974). That penalty makes night noise count for more, yet the result still blends day and night into one number. It also says nothing about peaks, so the WHO pair is the closer guide for sleep.
Which number should you compare a night sound against?
Steady sounds belong against the 30 dB average and sudden ones against the 45 dB peak; outdoor yearly figures are for planning, not rooms.
The published figures only help if you hold each sound against the right one. Steady sounds go against the 30 dB average, sudden ones against the 45 dB peak, and outdoor long-term figures belong to planners. The table below is our reading of common night sounds against those figures. No agency or seller publishes it, and it rests only on the sources cited above.
| Night sound | Behaves as | Figure to compare it with | Our reading |
|---|---|---|---|
| Fan, air conditioner or refrigerator hum | Steady | 30 dB average | Above 30 dB at the pillow all night puts the average past the WHO figure with no single loud moment |
| Sound machine you set yourself | Steady, chosen | 30 dB average | It will usually lift the average; the trade is that fewer peaks stand out above it |
| Car door, motorbike, barking dog | Single events | 45 dB peak, reactions from about 33 dB | Count the peaks over 45 dB; a handful each night matters more than the average |
| Trains or planes overhead | Repeated events | 45 dB peak indoors; 40 to 44 dB Lnight outside for planning (WHO compendium, 2022) | The outdoor figure describes the area; the indoor peak describes your night |
| Traffic on a nearby road | Steady hum with peaks | Both | Check the window first, since open and closed differed by about 18 dB in one study |
If your log shows a low average but repeated peaks, the problem is events rather than background. The fixes differ. Background noise responds to sealing and masking, while peaks respond to distance and the window.
Common questions
Short answers to the questions people often ask about bedroom decibels, each tied back to the published figures used in this guide.
Is 40 dB too loud to sleep?
As a steady all-night average, 40 dB is 10 dB above the WHO's 30 dB bedroom guideline (WHO, 1999). As a single peak it is under the 45 dB event figure, though pooled field studies record some extra awakenings from peaks of 33 to 38 dBA (Basner and McGuire, 2018).
Is 50 dB too loud for a bedroom at night?
Yes, by every figure here. A 50 dB peak is over the WHO's 45 dB single-event value, and a 50 dB average would sit 20 dB past the 30 dB bedroom average (WHO, 1999).
Do the WHO limits apply in the United States?
They are health guidelines, not US law. Federal figures in the United States use the 45 dB day-night average from the EPA and HUD instead (24 CFR 51.101), and that measure has no separate night or peak value.
Does a white noise machine count toward the 30 dB average?
It does. The average covers all sound in the room, chosen or not, so a steady masking sound raises it. Whether that helps depends on how many waking peaks it hides from you.
Why are sleep noise figures written in dBA?
The A in dBA means the reading is weighted toward the pitches people hear best. The unit A-weighted dB (dBA) is used to indicate how humans hear a given sound (Environmental Health Perspectives), so a low rumble reads lower than its raw energy would suggest.
Can a phone app tell me if my bedroom meets these figures?
It can show when the loud moments happen and roughly how loud they are, which is enough to separate steady noise from peaks. Phone microphones are not calibrated instruments, so treat a reading a few decibels either side of 30 or 45 as a near miss rather than a clear pass or fail.
Sources
Night Air's reading for this piece, in the order it is cited, each with the question it helped answer.
- WHO, 1999 (ruidos.org), helped answer “Key Takeaways”; “What decibel level do health agencies publish for a bedroom at night?”; “What is the difference between average and peak noise at night?”; “At what decibel level does a single noise start to wake people?”; “How much does a closed window lower the noise in a bedroom?”; “Common questions”.
- Basner and McGuire, 2018 (pmc.ncbi.nlm.nih.gov), helped answer “Key Takeaways”; “At what decibel level does a single noise start to wake people?”; “Common questions”.
- Locher et al., 2018 (pmc.ncbi.nlm.nih.gov), helped answer “How much does a closed window lower the noise in a bedroom?”.
- Noise and Health, 2010 (journals.lww.com), helped answer “Key Takeaways”; “What is the difference between average and peak noise at night?”; “At what decibel level does a single noise start to wake people?”; “Why are many night noise limits measured outside the house?”.
- WHO compendium, 2022 (cdn.who.int), helped answer “Key Takeaways”; “What decibel level do health agencies publish for a bedroom at night?”; “Why are many night noise limits measured outside the house?”; “Which number should you compare a night sound against?”.
- WHO, 1999 summary (ruidos.org), helped answer “What decibel level do health agencies publish for a bedroom at night?”.
- EPA, 1974 (nonoise.org), helped answer “What decibel level do health agencies publish for a bedroom at night?”; “How quiet is 30 decibels compared with everyday sounds?”; “What do United States agencies publish for noise inside a home?”.
- HUD, 24 CFR 51.101 (law.cornell.edu), helped answer “What decibel level do health agencies publish for a bedroom at night?”; “What do United States agencies publish for noise inside a home?”; “Common questions”.
- Environmental Health Perspectives (ncbi.nlm.nih.gov), helped answer “How quiet is 30 decibels compared with everyday sounds?”; “Common questions”.
- Night Noise Guidelines abstract (wind-watch.org), helped answer “Why are many night noise limits measured outside the house?”.
- HUD Exchange (hudexchange.info), helped answer “What do United States agencies publish for noise inside a home?”.
