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What is brown noise, and why do people sleep with it?

Updated · Written by the Luleep team, based on the sources listed below.

Brown noise is the deepest of the common noise colours: a low, rumbling hum with most of its energy in the bass, like a distant waterfall or the roar inside a plane. Some people find it calmer than white or pink noise because it has almost no hiss. There is very little research on brown noise and sleep specifically, so treat it as a matter of taste — and keep it quiet.

What is brown noise?

Brown noise (also called red or Brownian noise) is random noise whose power drops steeply as the pitch rises — by about 6 decibels for every octave. Its name comes from Brownian motion, the random jiggling of particles described by the botanist Robert Brown, not from the colour.

Compared with its relatives:

  • White noise has equal energy at every frequency and sounds bright and hissy.
  • Pink noise has equal energy per octave and sounds softer, like steady rain.
  • Brown noise leans even further towards the bass: a deep, smooth rumble with very little “shhh”.

Why some people prefer it for sleep

Because high frequencies are what make noise feel sharp, brown noise is often described as warmer and less tiring to listen to for a long time. Its deep tone also overlaps with low sounds in a bedroom — a fridge, traffic rumble, a neighbour's music — so it can make them blend into the background.

The other side: brown noise is weaker at covering high, sudden sounds such as a squeaky door or a barking dog. If those are what wake you, pink or white noise may mask them better. Many people end up with a mix — for example brown noise low underneath, with rain or waves on top.

What the research says

Most studies on noise and sleep use white or broadband noise, and even for those a 2021 systematic review found the evidence of benefit to be of very low quality [1]. Brown noise has hardly been studied on its own. One 2025 lab study compared white, pink and brown noise and found no difference in a physiological marker of arousal (pupil size) between them [2]. In other words, there is no evidence that brown noise is “better for the brain” — but plenty of people simply like how it sounds, which is a fair reason to choose it.

Like any steady sound, it should not be loud. A 2026 sleep-lab study found that continuous pink noise played all night reduced REM sleep [3]; it is sensible to assume the same caution applies to other continuous noise.

How to use brown noise

  • Low and even. Set the volume so that it softens the room's sounds without being the loudest thing you hear.
  • Mind small speakers. Phone speakers reproduce bass poorly, so brown noise may sound thin; turning it up to compensate is not the answer. A small external speaker or a pillow speaker at low volume works better.
  • Combine it. If a single noise feels empty, add a natural sound — see our sleep sounds guide for ideas.
  • Use a timer if you only need help falling asleep.

Questions and answers

What is the difference between brown noise and white noise?

White noise has equal energy at all frequencies and sounds hissy. Brown noise has most of its energy in the low frequencies and sounds like a deep rumble. Brown noise is softer on the ear; white noise covers sharp, high sounds better.

Is brown noise good for sleep?

There is little research on brown noise itself. Some people find its deep tone relaxing and fall asleep more easily with it. If you like it, keep the volume low and consider a timer.

Is it harmful to listen to brown noise all night?

A quiet brown noise is unlikely to harm adults, but continuous noise all night may change sleep, as one 2026 study found for pink noise. A timer and a low volume are a sensible default.

Sources

  1. Riedy SM et al. Noise as a sleep aid: a systematic review. Sleep Medicine Reviews, 2021.
  2. Erfanian M, Chait M et al. Pupil-linked arousal does not differ between ‘white’, ‘pink’ and ‘brown’ noises. International Journal of Psychophysiology, 2025.
  3. Basner M, Smith MG et al. Efficacy of pink noise and earplugs for mitigating the effects of intermittent environmental noise exposure on sleep. Sleep, 2026.

This guide is general information, not medical advice. Luleep is for relaxation and is not a medical device. If you have ongoing trouble sleeping, or are worried about your health, talk to a doctor.