White, pink and brown noise: what’s the difference, and do they help you sleep?
“Coloured” noise is everywhere in sleep apps and sound machines. The colours describe something real: how a sound’s energy is spread from low to high pitches. Whether any of them helps you sleep is a different question, and the honest answer is less certain than the marketing suggests. Here’s what the colours mean and what the research says, including a careful 2026 study with an unexpected result.
What the colours mean
| Noise | How energy is spread | What it sounds like |
|---|---|---|
| White | Equal energy at every frequency | A bright, even hiss, like an untuned radio or TV. High pitches stand out because there are more of them. |
| Pink | Energy falls by 3 decibels per octave as pitch rises, so each octave has equal energy | Softer and fuller, like steady rain or a waterfall |
| Brown (also called red or Brownian) | Energy falls by 6 decibels per octave | A deep rumble, like distant thunder, heavy surf or the inside of an airplane cabin |
The name “brown” comes from Brownian motion, the random movement of particles, not from the colour. Many everyday sounds sit between these: a fan is close to pink or brown, depending on the fan.
Why people use noise for sleep
There are three common ideas about how it might help:
- Masking. What wakes you is often the jump in loudness when a sudden sound breaks the silence. A steady background makes that jump smaller.
- A sleep cue. Hearing the same sound every night can become part of your routine, like turning off the lights.
- Lulling. Some people simply find a steady sound calming, or find silence uncomfortable.
What the research says
The evidence is weaker and more mixed than most apps suggest.
- A 2021 systematic review of 38 studies of continuous noise as a sleep aid, published in Sleep Medicine Reviews, found the overall quality of evidence was very low. The studies were small and too different from one another to support a firm conclusion.
- A 2022 systematic review in the Journal of Clinical Sleep Medicine looked at 34 studies. About a third of the white noise studies and most of the pink noise studies reported some improvement in sleep, and none reported harm from short-term use. But the authors also found no strong evidence overall.
- Laboratory studies of pink noise found it could deepen slow-wave sleep in some people. Many of those studies timed short bursts of sound to match the sleeper’s brain waves, which is not what a sleep app does when it plays noise all night.
- A careful 2026 study published in Sleep put 25 healthy young adults in a sleep laboratory for seven nights. Foam earplugs protected deep sleep from traffic and other disruptive noises well. Pink noise did not: used to mask the disruptive noise, it made sleep worse overall, and on its own it reduced REM sleep by about 18 minutes compared with a quiet night. The study was small and short, and it’s possible the brain adapts over longer use, but it’s a clear reason not to assume noise is automatically good for sleep.
So should you use it?
If you sleep well in silence, there’s no evidence you need noise. If a steady sound helps you relax or blocks a noise you can’t control, it’s reasonable to use, with a few precautions:
- Keep it quiet. Just loud enough to soften background sounds, well below conversation level. Some devices and apps can play noise loud enough to be a hearing risk over a whole night.
- Put the source away from your head. Across the room rather than on the pillow.
- Try a timer. If noise helps you fall asleep, letting it fade out after you’re asleep avoids exposing you to it all night.
- Consider earplugs if your problem is outside noise. In the 2026 study, they worked better than pink noise. They aren’t for everyone, and they can block sounds you need to hear, like a baby or an alarm.
- Be extra careful with babies. Keep any sound machine well away from the crib and at a low volume.
- See a doctor if you have trouble sleeping most nights. Ongoing insomnia has effective treatments, and noise isn’t one of them.
Which colour, if any?
There’s no strong evidence that one colour is better for sleep than another. In practice it’s a matter of comfort: many people find white noise harsh and prefer the softer sound of pink noise, or the deeper rumble of brown noise. Natural sounds with a steady texture, such as rain, are close to pink noise and work the same way. Sounds with sudden changes, such as thunderclaps or birdsong, are more likely to disturb you.
Our Sleep Buddy app lets you try white, pink and brown noise, rain and other steady sounds at low volume, with a timer that fades the sound out after you fall asleep.
Sources
- Riedy SM, Smith MG, Rocha S, Basner M. Noise as a sleep aid: a systematic review. Sleep Medicine Reviews, 2021.
- Capezuti E, et al. Systematic review: auditory stimulation and sleep. Journal of Clinical Sleep Medicine, 2022.
- Laboratory study of pink noise and earplugs against environmental noise during sleep. Sleep, 2026.
- McGill Office for Science and Society, White noise may worsen sleep, 2026.
This guide is general information, not medical advice. If poor sleep is affecting your health, mood or daily life, talk to your doctor.