White noise for sleep: what the studies say and how to use it with a baby

White noise does not cure anything, and it does not put anyone to sleep on its own. It is a steady sound that covers the odd noises from the house and the street. Some people and some babies find it easier to drop off with it; others do not. Below: what each kind of noise is, what the studies measured (with a link to each), what they do not show, and how to use it sensibly, especially with a baby.

This article is for information only and does not replace advice from your GP, health visitor or paediatrician. If you or your baby regularly struggle to sleep, talk to them.

White, pink and brown

All three are continuous noises. The difference is how they spread their energy between low and high frequencies. This is how Harvard Health Publishing (2025) describes them:

Rain, a fan or the sea are not white noise in the strict sense, but they are also steady sounds covering many frequencies at once. The review cited below groups exactly that: “continuous white noise or similar broadband noise”.

Which one to choose is a matter of taste. If white sounds too hissy, try pink or brown.

Why a steady sound can help

It hides sudden changes

What wakes you is not only how loud something is but the jump between the background and the noise. In a sleep-lab study with healthy volunteers (Stanchina and colleagues, 2005), four people slept with recordings of intensive-care-unit noise. Arousals rose from 13.3 an hour on the quiet night to 48.4 with the ICU noise. When white noise was added to the same ICU noise, they stayed at 15.7. The authors put it down to white noise narrowing the gap between background and peaks.

It is a tiny study, with adults, in a lab. But it explains the mechanism well: against a steady background, the door, the motorbike or the lift stand out less.

Newborns: a small trial from 1990

The most cited study on babies is by Spencer and colleagues, published in 1990 in Archives of Disease in Childhood. Forty newborns aged 2 to 7 days were randomly split into two groups of 20. With white noise, 16 (80%) fell asleep within five minutes. In the group without it, 5 (25%) did. The authors put it cautiously: white noise may help mothers settle difficult babies.

That is 40 babies in their first week of life, in a study more than thirty years old. It says nothing about older babies or about using it every night for months.

What the most thorough review found

In 2021 a team at the University of Pennsylvania reviewed 38 articles on continuous noise and sleep (Riedy and colleagues, Sleep Medicine Reviews). The findings ran from one extreme to the other: in some studies noise improved sleep, in others it disrupted it. Using the GRADE criteria, they rated the quality of evidence that continuous noise improves sleep as very low, and warned that it may also affect sleep and hearing.

In short: white noise can help some people fall asleep, especially when there is noise to cover. It is not a treatment and it does not work for everyone.

As part of a routine

A routine that is the same every night is well supported. In a trial with 405 mothers and their children aged 7 to 36 months (Mindell and colleagues, 2009), a routine of bath, massage and quiet time, with cuddles or a lullaby, cut how long the children took to fall asleep and how often they woke at night within two weeks.

There was no white noise in that routine. If you use it, it can be the last step, always the same. What we have not found is a study that measures, on its own, whether the sound works as a sleep cue.

What about sound for deep sleep?

You may have read that certain sounds boost deep sleep. Those studies do not play a continuous noise: they play short sounds timed in real time to the brain’s slow waves (Ngo and colleagues, 2013). The Riedy review left them out for exactly that reason. A speaker or an app that plays non-stop does not do the same thing.

With a baby: quiet, away and not all night

In 2014 a team at the Hospital for Sick Children in Toronto measured 14 infant sleep machines at maximum volume (Hugh and colleagues, Pediatrics):

• At 30 cm, all of them went above 50 dBA, the noise limit recommended for infants in hospital nurseries.
• Three went above 85 dBA. More than 8 hours at that level exceeds the workplace noise limits for adults.
• Even at about 2 metres, all but one could exceed 50 dBA (NPR).

The study measured what the machines can produce, not how families use them. Nor is it known whether babies exposed to them are harmed, because no large studies have checked (NPR). Phones were not measured, but the advice applies to any speaker.

This is what the study’s authors and the American Academy of Pediatrics (AAP) advise:

1. Away. As far from the baby’s head as possible (AAP, HealthyChildren.org). Never in the cot or on the rail (NPR). With a phone: on a chest of drawers or a shelf across the room.
2. Quiet. Keep the volume low (NPR). Start at the lowest setting and turn it up only as far as you need to cover the background noise.
3. Short. A little while, not all night, say the authors; “for a short time only”, says the AAP. The practical way is a timer that switches it off once the baby is asleep.

White noise does not replace any of your health visitor’s or paediatrician’s safe-sleep advice.

For adults: a timer or until morning

For adults, Harvard Health advises a volume no louder than a background conversation, the device in a corner of the bedroom and, ideally, a timer so it plays while you fall asleep rather than all night. The Riedy review notes that noise can also affect sleep and hearing.

Two ways to use the timer:

• For a while. Set it to how long you usually take to fall asleep, with some margin. If the sound fades out at the end, there is no sudden cut.
• Until a set time. If your street gets noisy before dawn, with the bin lorry or the first bus, you can leave it on until 7:00, say, and let it switch off by itself. If you do, keep it quiet.

With a baby, stick to the short timer from the section above.

Nanu, our white noise app

At X MAXIMUS LABS we make Nanu, a white noise app for iPhone, made for babies and for adults:

• 21 sounds created on the iPhone itself, looping without a seam: white, pink and brown noise; shush, heartbeat, womb, hair dryer, vacuum and music box; rain, ocean, stream, wind, campfire and crickets; fan, airplane, night train, car ride, washing machine and deep rumble.
• A timer from 15 minutes to 10 hours, or until a set time, with a gentle fade-out from 10 seconds to 10 minutes.
• Keeps playing with the screen off, with controls on the lock screen. Works with Bluetooth and AirPlay speakers, Siri and Shortcuts.
• Mixes of up to four sounds, each with its own volume.
• No ads, no account and no tracking.

Free: every sound, for up to 30 minutes at a time, with 15- and 30-minute timers. Nanu Plus adds all-night playback, longer timers, stopping at a set time, and mixes. It comes as a monthly or yearly subscription (the yearly plan starts with 3 free nights) or a one-time purchase; the App Store shows the price in your currency.

Nanu is not a medical device and does not replace your doctor or health visitor, and none of the studies in this article tested it.

Nanu on the App Store · Questions: info@xmax.es · Privacy

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Sources:

• Spencer, J. A., Moran, D. J., Lee, A. and Talbert, D. (1990). ‘White noise and sleep induction’. Archives of Disease in Childhood, 65(1), 135–137. PMC1792397
• Hugh, S. C., Wolter, N. E., Propst, E. J., Gordon, K. A., Cushing, S. L. and Papsin, B. C. (2014). ‘Infant sleep machines and hazardous sound pressure levels’. Pediatrics, 133(4), 677–681. PubMed 24590753
• Hobson, K. (3 March 2014). ‘Noise machines to help babies sleep can raise quite a din’. NPR. npr.org
• American Academy of Pediatrics (2023). ‘How Noise Affects Children’. HealthyChildren.org. healthychildren.org
• Riedy, S. M., Smith, M. G., Rocha, S. and Basner, M. (2021). ‘Noise as a sleep aid: A systematic review’. Sleep Medicine Reviews, 55, 101385. PubMed 33007706
• Stanchina, M. L., Abu-Hijleh, M., Chaudhry, B. K., Carlisle, C. C. and Millman, R. P. (2005). ‘The influence of white noise on sleep in subjects exposed to ICU noise’. Sleep Medicine, 6(5), 423–428. PubMed 16139772
• Mindell, J. A., Telofski, L. S., Wiegand, B. and Kurtz, E. S. (2009). ‘A nightly bedtime routine: impact on sleep in young children and maternal mood’. Sleep, 32(5), 599–606. PMC2675894
• Ngo, H. V., Martinetz, T., Born, J. and Mölle, M. (2013). ‘Auditory closed-loop stimulation of the sleep slow oscillation enhances memory’. Neuron, 78(3), 545–553. PubMed 23583623
• Catanese, L. (31 March 2025). ‘Can white noise really help you sleep better?’. Harvard Health Publishing. health.harvard.edu