White noise for sleep, study and a quieter room

What is white noise?

White noise is a random sound whose power is spread evenly across all frequencies: every band of equal width in hertz carries the same power. The band from 40 to 60 Hz holds as much energy as the band from 400 to 420 Hz. The name comes from a loose analogy with white light, which contains all visible colours.

Even energy per hertz does not sound even to the ear. We hear pitch in octaves, and each octave is twice as wide as the one below it. The octave from 5,000 to 10,000 Hz is 5,000 Hz wide, the octave from 50 to 100 Hz only 50 Hz wide, so in white noise the upper one carries a hundred times more power. That is why white noise sounds bright and hissy, like static between radio stations or air escaping from a tyre.

The other noise colours tilt this balance: pink noise gives every octave the same power, brown noise loses even more at the top. This page is about white noise and steady noise in general, because most sleep research used white or similar broadband sound.

How does white noise work? Masking explained

White noise works by auditory masking: a steady sound raises the threshold at which other sounds can be heard. It is one of the oldest findings of the psychology of hearing, described in Harvey Fletcher's paper on auditory patterns (1940) and in standard textbooks such as Brian Moore's An Introduction to the Psychology of Hearing. Masking is strongest when the two sounds share frequencies, which is why a broad noise that covers the whole range masks such a wide variety of sounds.

For sleep, the key question is what actually wakes you. A small sleep-lab study in the United States (Stanchina and colleagues, 2005) played recorded intensive-care-unit noise to sleeping volunteers. Arousals per hour went from 13.3 on a quiet baseline night to 48.4 with the hospital noise. With the same hospital noise plus white noise they fell to 15.7, close to the quiet night.

The explanation was in the numbers. Arousals depended on the change in sound from the background to the peak, about 17.5 dB in both noisy conditions, not on how loud the peak was. White noise raised the background, so the same alarms and voices produced a smaller jump. The study was very small, with four or five people, but it shows the mechanism clearly: steady noise does not remove the disturbing sound, it reduces the contrast.

This also explains the limits: a sound much louder than the noise, or far below it in pitch, still gets through, and the noise itself adds sound to the room, which matters for volume.

Does white noise help you sleep? What the studies found

White noise helps sleep most clearly in noisy surroundings; in a quiet bedroom the evidence is weak. The broadest summary is a systematic review in Sleep Medicine Reviews (Riedy, Smith, Rocha and Basner, 2021). It found 38 studies of continuous white or similar broadband noise. Results ranged from better sleep to worse, and the studies differed widely in noise type, measurement and controls. Using the GRADE criteria, the authors rated the quality of evidence that continuous noise improves sleep as very low, which, as they note, contradicts its widespread use.

The individual studies with positive results mostly come from wards, clinics and loud cities:

Read together, these studies say something specific: steady noise helped where something else was waking people, such as monitors, staff or traffic. The one lab study with healthy people showed faster sleep onset, not a deeper or longer night. All were small, and several had no proper control group.

Is white noise bad for sleep? When it is not worth it

White noise is not worth playing all night in a bedroom that is already quiet, and there is some evidence that constant noise can make sleep worse. The authors of the 2021 systematic review warn that continuous noise may also negatively affect sleep and hearing and ask for studies with objective sleep measures before it is promoted as a sleep aid.

The most careful recent study points the same way. In a sleep laboratory (Basner and colleagues, 2026), 25 adults spent seven nights each with full sleep recording. Steady pink noise on its own shortened REM sleep, and earplugs protected sleep from traffic-type noise far better than added noise did. That study is described in detail on the pink noise page; its lesson for white noise is simple: if you want less noise, reducing it beats covering it.

So for a noisy bedroom: reduce the source if you can (window, door, heavier curtains), try earplugs, and use steady noise when those do not work for you, at the lowest level that covers the disturbing sounds.

How loud should white noise be for sleep?

White noise for sleep should be only as loud as it takes to cover the sounds that disturb you, and in a bedroom that means well below conversation level. The World Health Organization's Guidelines for Community Noise (1999) recommend that continuous noise inside a bedroom stay below 30 dB LAeq and that single noise events not exceed 45 dB LAmax; measurable effects on sleep start from about 30 dB.

Studies that found a benefit used modest levels too: 46 dB in the Messineo lab study, 50–60 dB on the cardiac ward, where the ward itself was loud. The more the surroundings are quiet, the less noise you need, because masking depends on the jump between background and peak.

Eight hours of sound every night adds up to 56 hours a week, more than the 40 hours behind the WHO limit, so a sleep sound should sit far below 80 dB. A practical test: you should be able to talk quietly over it. For babies, see the page about white noise for babies.

Should you play white noise all night or use a timer?

Use a timer if your problem is falling asleep, and play it through the night only if noise wakes you later. The evidence splits the same way. The clearest lab result, from Messineo 2017, was a shorter time to fall asleep, which needs sound only at the start. The studies on wards and in New York bedrooms measured night waking caused by noise during the night, and there the sound has to be present when the noise happens.

If you do play it all night, three habits keep the dose low. Put the speaker away from your head, at the other side of the room or at least on a far shelf, not on the pillow. Prefer a speaker to earphones, because the sound level at the eardrum falls quickly with distance. Keep the volume at the lowest level that still covers the peaks.

No studies have followed the hearing of adults who used white noise every night for years. That is not proof of harm, but it is a reason to keep the level low.

White noise machine, app or a free white noise generator

A white noise machine, a phone app, a fan and a free online generator all produce steady broadband sound; they differ in sound, control and what comes with them.

The mixer on this page makes every sound in your browser, nothing is recorded or streamed. It has seven noise colours (white, pink, brown, green, grey, blue, violet) and seven nature sounds (rain, thunder, ocean, wind, stream, fire, fan), each with its own volume, ready mixes for sleep, a baby, focus, meditation, a rainy night, a fan and deep brown noise, and a timer from 15 minutes to 8 hours that fades the sound out over the last minute.

People search for white noise 10 hours because they want a sound that lasts until morning. A generator needs no long file: it produces the noise as it plays, so the length is set by the timer.

Does white noise help you study or focus?

White noise helps some people concentrate and hinders others, and the dividing line in the research is ADHD. A Swedish study (Söderlund, Sikström and Smart, 2007) gave children memory tasks with and without white noise. Children with ADHD remembered more with the noise; the control children remembered less.

A meta-analysis in the Journal of the American Academy of Child and Adolescent Psychiatry (Nigg and colleagues, 2024) confirmed the pattern. In 13 studies with 335 children and college-age young adults with ADHD or ADHD symptoms, white and pink noise gave a small but significant benefit on lab attention tasks (effect size g = 0.249). In 11 studies of people without ADHD the effect was negative (g = −0.212). The results were consistent across studies, with no sign of publication bias.

The Swedish authors explain the split with the moderate brain arousal model: some noise helps a system with low dopamine through stochastic resonance, and the ideal amount depends on the person. For studying, that suggests a simple experiment: work on the same kind of task for a few days with quiet noise and a few days without, and compare. Without attention difficulties, the average result favours quiet. No study has tested brown noise for focus; see the brown noise page.

White noise for tinnitus: does it help?

White noise does not cure tinnitus, but many people find that background sound makes it easier to live with. The American clinical practice guideline on tinnitus (Tunkel and colleagues, 2014, American Academy of Otolaryngology–Head and Neck Surgery) grades sound therapy as an option: doctors may recommend it for persistent, bothersome tinnitus. Two things have stronger recommendations: a hearing-aid evaluation when there is hearing loss, and cognitive behavioural therapy. The same guideline recommends against drugs, supplements such as Ginkgo biloba, melatonin or zinc, and transcranial magnetic stimulation for routine treatment.

A Cochrane review (Sereda and colleagues, 2018) of 8 trials with 590 people found that users of every device improved over time, but no trial compared a device with no device in a usable way, so there is no proof that sound therapy beats a waiting list, a placebo or education alone. The evidence quality was low.

If tinnitus bothers you, the guideline's stronger steps come first: a hearing check and, if needed, cognitive behavioural therapy. For everyday use, keep the noise soft: the aim is a background that takes the edge off the silence, not a sound that competes with the tinnitus at high volume.

White noise or pink, brown or green noise: which to choose

Choose the colour you find pleasant at a low volume, because no study has compared the colours head to head for sleep. The practical difference is where the energy sits: white noise is the brightest and covers high, hissing sounds well; pink noise gives every octave equal power; brown noise is a deep rumble that covers low sounds better; green noise is a marketing name for pink-like noise centred around 500 Hz. Each has its own page, and rain, ocean and fan sounds have theirs.

A simple way to decide: play each colour for a minute at the same low volume, lying down, and keep the one you stop noticing first. The side-by-side chart of all the colours is on the page about the colors of noise.