Medically reviewed by Dr Chris Dickson, MBBS, MRCGP. Last reviewed 29 September 2026.
White noise machines can make some ambient sounds less noticeable when outside noise is disturbing you. They do not silence the environment: a loud or sudden sound may still wake you. The evidence that white noise improves sleep more generally is mixed, and there isn't a strong case for everyone to leave a machine running all night. Your bedroom, the volume, the duration of exposure and what's keeping you awake all matter.12
If a white noise machine already helps you, that experience counts.
What does a white noise machine do?
A car passing a quiet bedroom creates a sudden change in sound. Add a steady background hiss, and the car may stand out less. That's sound masking: the traffic still reaches the room, but the difference between the background and the disturbance is smaller. It does not stop you hearing the room, and it cannot guarantee that an alerting sound will go unnoticed.
This gives white noise a practical job. If you sleep beside a busy road, share a wall with late-night television or work shifts while the rest of the house is awake, masking can make your surroundings easier to sleep in.
It also explains why results vary. A machine has less obvious work to do in a bedroom that's already quiet. And adding sound changes the sleeping environment in its own right, which researchers need to measure alongside any benefit from masking.1
White, pink and brown noise
These names describe how sound energy is distributed across frequencies. White noise has equal energy per unit of frequency across its range, producing the familiar hiss. Pink noise gives relatively more weight to lower frequencies; brown noise shifts the balance further towards a low rumble.
Products often put these sounds beside rain, waves and fans under one “sleep sounds” menu. A preference for one sound tells you what you find comfortable. It doesn't tell you which will improve your sleep.
Our guide to the science and history of sound therapy explains the wider uses of sound. Here, the question is what a machine playing continuous noise can do at bedtime.
Does white noise help you sleep?
A small study found benefits in noisy bedrooms
In 2021, researchers studied 10 adults in New York City who reported trouble sleeping because of environmental noise. Participants spent a week sleeping normally, a week using a white noise machine and another week without it.2
With white noise, participants reported falling asleep faster, and wrist-based monitoring recorded less time awake after they first fell asleep. The study supports trying masking when noise is the problem, although 10 people and a week of use tell us little about long-term effects or people sleeping in quiet rooms.
The reviews found an uncertain evidence base
A 2021 systematic review by Riedy and colleagues examined 38 articles on continuous white noise or similar broadband sound. Results varied considerably, with some studies finding better sleep and others finding disruption. The reviewers rated the evidence that continuous noise improves sleep as very low quality.1
A separate review published in the Journal of Clinical Sleep Medicine in 2022 examined 34 studies of white noise, pink noise and mixed audio. It found some encouraging results, but weaknesses in study design and inconsistent methods made firm conclusions difficult. Only one included study directly compared white and pink noise.3
Someone sleeping through hospital alarms has a different problem from someone lying awake in a quiet home. Falling asleep faster, waking less often and feeling more rested are also separate outcomes.
A larger trial included white and pink noise
The 2026 USleep randomised controlled trial assigned 495 working adults to four app-based groups for four weeks. Its Sleep Sounds library included white and pink noise alongside music and nature sounds. Every group improved, but Sleep Sounds showed no statistically significant advantage over the digital control on reported sleep disturbance.13
The trial assessed access to a mixed sound library. It didn't isolate white or pink noise, test a dedicated bedside machine or compare either with SleepEngine™. We explain the findings in our article on sleep-sound apps.
A newer pink-noise study adds caution
In a 2026 laboratory study, 25 healthy adults spent seven nights under different sound conditions. Researchers tested environmental noise, continuous pink noise at 40 or 50 dBA, earplugs and combinations of these, recording sleep with polysomnography.4
Pink noise reduced REM sleep compared with the quiet control night. Adding it to environmental noise worsened overall sleep structure despite some improvements in specific measures of disruption. Earplugs protected sleep more effectively in that experiment.
This was an adult study of particular sound levels over a short period. It doesn't tell us what every household machine does or what happens to babies exposed to sound. It does give us a reason to question automatic, all-night use of broadband noise.
Is pink noise better for sleep than white noise?
There isn't enough reliable comparative evidence to name a winner for everyday use.3
Some promising pink-noise research uses carefully timed pulses. In a 2017 study of 13 older adults, researchers monitored brain activity and timed sound to the participants' slow brainwaves. They recorded increased slow-wave activity and better overnight word-pair recall.5
The timing was part of the intervention. An ordinary speaker playing a continuous pink-noise track doesn't reproduce that experiment. The same care applies to claims about brown noise: a deeper sound can be pleasant without having demonstrated a greater sleep benefit.
Volume, babies and everyday use
Can white noise damage your hearing?
Sound can damage hearing if the exposure is loud enough or lasts long enough. The US National Institute on Deafness and Other Communication Disorders explains that risk depends on sound level, duration and distance from the source. Longer or repeated exposure increases the total dose, so a sound that is not immediately uncomfortable should not automatically be treated as suitable for continuous nightly use.6
Keep any masking sound as quiet as you can while still finding it useful. Don't keep turning it up to compete with a disturbance that would be better addressed at its source. What counts is the sound reaching your ears where you sleep. The percentage on the volume control won't tell you that.
What about white noise for babies?
Adult sleep research and occupational noise limits cannot establish what is safe for an infant. In a 2014 study, researchers tested 14 infant sleep machines at their maximum settings and found that some could produce levels above adult occupational exposure limits. That was a measurement of machine output, rather than a study showing hearing damage in babies, and adult workplace limits should not be interpreted as infant safety thresholds.7
The American Academy of Pediatrics advises placing a machine as far from the baby as possible, choosing the lowest volume and limiting how long it runs. Its parent guidance also recommends short use and distance from the baby's head. Ask your child's clinician if you're unsure about your setup.89
Can you become dependent on white noise?
The studies discussed here don't settle whether years of nightly use make it harder to sleep without sound. They're too varied and generally too short to answer that question.13
If you prefer a familiar sound at bedtime, consider whether it continues to help and whether you can sleep comfortably when travelling without it. Feeling reassured by a routine isn't, by itself, a medical dependence.
Does it help tinnitus?
The NHS says gentle background sound can distract from tinnitus and advises seeing a GP when tinnitus is persistent, worsening or affecting sleep. An audiologist can help you choose an appropriate approach. A white noise machine isn't a treatment for the underlying cause.10
How is SleepEngine™ different from white noise?
We make SleepEngine™ POD. Its audio uses a programmed sequence of low-frequency soundwaves, and the POD plays it from under your pillow, behind it or on your bedside table.
Barely audible and working passively while you sleep, the soundwaves guide your brain through the sequence of healthy sleep cycles, improving sleep quality.
SleepEngine™ can also play repetitive nature soundscapes, such as ocean waves. These are separate from SleepEngine™ Sounds, the programmed soundwaves. Their role in the product design is to provide a familiar, repetitive background so the programmed sound is less likely to attract conscious attention. They aren't the active SleepEngine™ mechanism.
SleepEngine™ doesn't measure your brainwaves or adjust its output in response to EEG. Its studies measured reported sleep outcomes. They didn't measure brainwave entrainment, and the timed pink-noise research above isn't evidence for SleepEngine™.
Two independently run clinical studies. 94% slept better.*
*Based on two independently run clinical studies (n=53 total). “Sleep better” refers to participants' self-reported improvement during the study period when used as instructed. Individual results may vary.
Thirty-six adults with insomnia symptoms kept nightly sleep diaries for three weeks, in a study run by CMR, an independent research company. On the first night they slept 4.2 hours on average. By night 21 that was 6.8 hours, they were waking 1.2 times a night instead of 2.7, and their average sleep efficiency had gone from 59% to 87%.
In the more recent study, participants' scores improved over twelve weeks of nightly use, and the improvement in sleep quality still held eight weeks after participants stopped using the device. Sleep quality was measured with the Pittsburgh Sleep Quality Index, a validated measure of sleep quality.11
We recommend continued use.
Those results don't show SleepEngine™ works better than a white noise machine: neither study made that direct comparison. They give you a separate body of evidence to consider alongside how the sound is delivered and what you want it to do.
Read more about SleepEngine™ technology, or compare the practical differences between sleep earbuds, headbands and wearable-free devices.
Should you buy a white noise machine?
If outside noise is keeping you awake, a basic white noise machine or a fan may be enough. Start by reducing the disturbance where possible, then see whether quiet masking makes a noticeable difference to your sleep and how you feel the next day.
If your room is already quiet, the research gives you little reason to assume that adding continuous noise will improve it. Persistent difficulty sleeping deserves attention to its cause. The NHS recommends seeing a GP when sleep problems have continued for months or make daily life hard to manage; cognitive behavioural therapy may be offered.12
For an adult considering programmed sleep audio without anything to wear, see where to buy SleepEngine™ POD.
Frequently asked questions
Do white noise machines actually work?
They can mask disruptive sounds, and a small study found sleep benefits in adults with noisy bedrooms. Broader reviews found uncertain evidence for improving sleep across different settings. The benefit depends partly on what is disturbing you.123
Is it bad to sleep with white noise every night?
Research hasn't established a universal benefit or the long-term effects of nightly use. Hearing risk depends on sound level, duration and distance, so prolonged exposure deserves care even when the sound does not feel immediately loud. If it isn't helping, there's little reason to add sound to your bedroom.16
Is white noise safe for babies?
Safety depends on the exposure. The American Academy of Pediatrics recommends distance from the baby, low volume and limited use. Evidence and exposure limits developed for adults cannot be assumed to establish safety for infants.89
Can I use a fan instead?
A fan can supply steady background sound for masking. Whether it helps will depend on the disturbance, the sound it makes and your comfort. You don't need a dedicated white noise machine just to create background sound.
Sources
- Riedy SM et al. “Noise as a sleep aid: a systematic review.” Sleep Medicine Reviews, 2021;55:101385
- Ebben MR, Yan P, Krieger AC. “The effects of white noise on sleep and duration in individuals living in a high noise environment in New York City.” Sleep Medicine, 2021;83:256–259
- Systematic review: auditory stimulation and sleep. Journal of Clinical Sleep Medicine, 2022;18(6):1697–1709
- Basner M et al. “Efficacy of pink noise and earplugs for mitigating the effects of intermittent environmental noise exposure on sleep.” Sleep, 2026;zsag001 (open manuscript)
- Papalambros NA et al. “Acoustic enhancement of sleep slow oscillations and concomitant memory improvement in older adults.” Frontiers in Human Neuroscience, 2017;11:109
- US National Institute on Deafness and Other Communication Disorders. Noise-induced hearing loss
- Hugh SC et al. “Infant sleep machines and hazardous sound pressure levels.” Pediatrics, 2014;133(4):677–681
- American Academy of Pediatrics. “Preventing excessive noise exposure in infants, children, and adolescents.” Policy statement. Pediatrics, 2023;152(5):e2023063752
- American Academy of Pediatrics, 2023. How noise affects children
- NHS. Tinnitus
- Cambridge Sleep Sciences: Creative Medical Research, Sounding Out the Sleep Infuser, 2016, company-held report; Sackier, Guest and Dsouza, “Audio neuromodulation to treat adult insomnia: an observational study”, 2025. Company report of the second study
- NHS. Insomnia
- Vazzaz J et al. “USleep: efficacy of app-based audio interventions to improve sleep disturbance in working adults, a multi-arm randomized controlled trial.” Sleep, 2026;49(9):zsag154
