How Loud Is Too Loud at Night? Noise and Sleep
The short answer: a quiet bedroom is around 30 dB, and steady noise above about 45 dB is where sleep starts to suffer. WHO's night limit for road traffic outside a bedroom is 45 dB Lnight; for aircraft noise it is 40.
The numbers that matter at night
Night noise is judged against much lower numbers than daytime noise, because sleep is the point. WHO's 2018 environmental noise guidelines recommend these night limits, measured outside the bedroom:
| Source | Lnight | Day-evening-night (Lden) |
|---|---|---|
| Road traffic | 45 dB | 53 dB |
| Railway | 44 dB | 54 dB |
| Aircraft | 40 dB | 45 dB |
| Wind turbines | 45 dB | 45 dB |
Those are outdoor levels. A closed window takes maybe 20–30 dB off typical traffic noise depending on the window, so being under the outdoor limit does not guarantee a quiet room. For the room itself, older WHO guidance is more useful to a household: about 30 dB for good sleep, with single loud events kept under roughly 45 dB.
What different levels feel like at night
| Level | Sounds like | What it does |
|---|---|---|
| 30 dB | Quiet bedroom, soft whisper | Where most people sleep best |
| 40 dB | Quiet library, fridge hum in the next room | About the top of a comfortable room |
| 45 dB | Steady road traffic heard from indoors | WHO Lnight limit for road traffic outside the bedroom |
| 50 dB | Normal conversation, a fan on high | Enough to lighten sleep for many people |
| 55–60 dB | A television in the next room | Wakes light sleepers, fragments deep sleep |
| 70 dB+ | Vacuum cleaner, loud music through a wall | Clearly disruptive even for heavy sleepers |
The jump from 45 to 55 dB looks tiny and is not: 10 dB is ten times the sound energy. That is why a television through a wall is a completely different problem from a fridge humming, even though both are "just background noise" in conversation.
Why you can sleep through it and still feel terrible
Sleep is not a switch. Noise pushes you out of deep sleep and into lighter stages, and it does that without a full awakening you would remember. Heart rate and stress hormones rise with each event. Over a night of on-and-off noise, you can log eight hours, remember none of the interruptions, and still wake up flat.
This is the part people underestimate when they say they have "got used to it". Habituation changes how much you notice the noise. It does not stop the body responding to it.
Measure the right thing
If you are going to do anything about it — a complaint, a conversation with a neighbor, a new window — measure properly first:
- At the bed, at ear height. That is what you actually sleep in. Not the doorway, not the middle of the room.
- Take a quiet baseline. A few minutes with nothing happening gives you the number to compare against. Without it, "it was 48 dB" means nothing.
- Note times and duration, not just the peak. A 30-second door slam and 90 minutes of bass are different problems with different fixes.
- Repeat on several nights. One bad night is not a pattern; four is.
The free decibel meter keeps the live level, the average and the peak on screen, which is enough to write a log. It does not record audio. A phone reading is a rough number, so if the noise turns into a formal complaint, read what a phone reading is worth before you put the figure in a letter.
What actually reduces night noise
In rough order of effect per euro, based on where the sound is getting in:
- Close the gap, not the wall. Draught strips around the window and door frame, a seal on the letterbox, and a chimney balloon cut more noise than thick curtains.
- Move the bed off the shared wall. Even a metre helps, and a headboard against an internal wall helps more.
- Fix the window before the room. Secondary glazing is usually the cheapest big step for traffic noise. Acoustic foam on the wall does very little for noise coming through a window.
- Earplugs for steady noise. They take the edge off a fan, traffic or a hum. They do much less for bass, footsteps and structure-borne sound, and the NRR on the box is optimistic — expect about half in real ears.
- Be careful with white noise. A fan or a noise app can mask a fridge hum, and it also adds sound. Keep it low and away from the head.
If the source is a neighbor, the practical route is a log and a calm conversation, then the landlord or local authority. How to measure noise from neighbors covers how to build that log so it is actually useful.
Questions
- How loud is too loud at night?
- WHO's 2018 guidelines recommend keeping road traffic noise outside a bedroom below an Lnight of 45 dB to protect sleep, and aircraft noise below 40 dB. For the room itself, older WHO guidance puts a comfortable bedroom at about 30 dB. In plain terms: a quiet room is close to a whisper, and steady noise above a quiet conversation level is enough to disturb sleep.
- Can noise wake me up without me noticing?
- Yes. Noise during sleep does not have to wake you fully to do damage to sleep quality: it can push you into lighter sleep and raise heart rate and stress hormones without you remembering anything in the morning. That is why "I slept through it" and "I feel wrecked" can both be true.
- What is Lnight?
- Lnight is the average noise level over the night period, usually 23:00 to 07:00, used in environmental noise rules. It is not a peak. A single door slam can be far above Lnight and still matter, which is why peak levels get their own limit in some rules.
- Do earplugs actually fix night noise?
- They help a lot with steady noise and less than the box claims. The NRR number on earplugs overstates real-world reduction; expect roughly half of it once they are actually in your ears. If the noise is bass-heavy, from footsteps or from the structure itself, earplugs do much less.
- Should I measure at the bed or at the wall?
- At the bed, at the height of your ears, is what you actually experience. The wall is where you find out where the noise is coming in. Measure both if you are building a case: the bed reading for the effect, the wall reading for the source.