White Noise for Babies

Does white noise actually help?

Yes, for a specific reason: it masks sudden changes in sound. A baby surfacing between sleep cycles is easily woken by a door, a sibling, or a car outside. Continuous sound raises the floor so those transients do not stand out. It is not sedating — it removes the thing that was waking your baby.

There is also a familiarity argument: the womb is a loud environment, roughly comparable to a running shower, so continuous low-frequency sound is not novel to a newborn. Evidence for white noise as a sleep intervention is modest but generally positive, with a frequently cited small 1990 study finding that most newborns fell asleep faster with continuous sound.

It is most useful if you live somewhere noisy, have older children, or your baby is in the 4 month sleep regression, where between-cycle wakings are the core problem.

Safe use: the three numbers

1. Below 50 dBA as measured at the baby’s head. This is the level the AAP has referenced for infant sleep environments — about the volume of a quiet conversation or a running fridge.
2. At least 2 metres (7 feet) from the crib. Never attached to the cot, never inside it. Sound intensity drops sharply with distance, so moving the machine across the room does most of the work.
3. Not at maximum volume. Most machines are dangerous at full volume. Set it once, at a level where you can comfortably talk over it in the room, and leave it.

A free sound-level meter app on your phone, held where your baby’s head is, gets you close enough. Phone apps are not calibrated instruments, but they will reliably tell you whether you are at 45 dB or 75 dB.

White, pink or brown?

• White noise has equal energy at every frequency, which makes it sound hissy and bright — like radio static.
• Pink noise reduces energy as frequency rises, so it sounds fuller and softer — steady rain, or wind in trees. Many people find it less fatiguing.
• Brown noise rolls off further and sounds deeper, like a distant waterfall.

There is no strong evidence that one outperforms the others for infant sleep. Lower-frequency sound (pink or brown) is generally more pleasant at low volumes and masks household noise adequately. Pick one and keep it consistent.

How to use it well

• Run it continuously through the sleep, rather than on a timer. If it switches off mid-sleep, the sudden silence is itself a change that can wake a baby — which defeats the purpose.
• Use it for naps too if daytime is noisy. Consistency helps it work as a cue.
• Keep it steady. Avoid sounds with melodies, waves, heartbeats or other variation — variation is exactly what you are trying to mask.
• Do not use headphones or in-crib speakers. Distance is a core part of the safety margin.

The reasonable objections

Dependency. Real, but mild and easy to unwind: reduce the volume gradually over one to two weeks. It is a far less demanding association than being rocked or fed to sleep. A machine that runs all night without anyone getting up is not much of a problem.

Language and hearing development. Concerns have been raised that constant background noise could affect auditory development, mostly extrapolated from animal studies using continuous high-level noise. At the volumes and durations recommended here — below 50 dBA, for sleep only — there is no evidence of harm. Do not run it through the day during awake time; babies need speech and quiet to learn from.

When to stop

There is no fixed age. Many families use it through toddlerhood, and plenty of adults use it themselves. If you want to phase it out, drop the volume by a small amount every few nights over a couple of weeks. The change is usually unremarkable if you do it gradually.

If white noise is not moving the needle, the cause is more often the schedule than the environment — check wake windows and room darkness first. And make sure the sleep space itself follows safe sleep guidelines: a machine must never sit in or on the cot.

Sources

• Hugh SC, Wolter NE, Propst EJ, Gordon KA, Cushing SL, Papsin BC, Infant sleep machines and hazardous sound pressure levels, Pediatrics (2014).
• Spencer JA, Moran DJ, Lee A, Talbert D, White noise and sleep induction, Archives of Disease in Childhood (1990).
• American Academy of Pediatrics guidance on noise exposure in infant sleep environments.

Common questions