White, pink, and brown noise are the same idea with the treble turned down by different amounts — white is bright and hissy, pink is softer, brown is a deep rumble. The honest part most articles skip: there’s little solid evidence that any of them improves sleep. What noise reliably does is mask other sounds. Here’s the real picture, and how to use it without fooling yourself.
What White, Pink, and Brown Noise Actually Are
All three mix many frequencies at once. The only difference is the balance.
- White noise — every frequency at roughly equal power. Sounds like static or an untuned radio. Bright, slightly hissy.
- Pink noise — higher frequencies turned down about 3 dB per octave. Sounds like steady rain. Softer than white.
- Brown noise — highs turned down further, about 6 dB per octave. A deep, low rumble like a waterfall or heavy surf. The warmest of the three.
There’s also blue noise, which boosts the high frequencies instead — bright and harsh, which is why nobody uses it to fall asleep.
That’s the whole science of the names. They describe a frequency curve, not a sleep benefit.
What the Evidence Actually Shows
This is where the marketing and the research part ways.
- “Noise helps you sleep” is weakly supported. A 2021 systematic review in Sleep Medicine Reviews pooled 38 studies and rated the evidence that continuous noise improves sleep as very low quality — with findings ranging from mild benefit to outright disruption. It’s not the slam-dunk sleep aid it’s sold as.
- The famous pink-noise result is narrower than it sounds. A 2017 study did increase deep sleep — but by playing short pink-noise pulses timed to each sleeper’s brain waves with an EEG rig, in a lab, in 13 older adults. That’s closed-loop stimulation, not a rain track on a loop. Streaming continuous pink noise from your phone is a different thing, and the evidence it does the same is thin.
- Noise can cut the other way. A 2023 study linked overnight pink noise at around 50 decibels to roughly 19 minutes less REM sleep. Played loudly all night, sound is also a hearing-exposure question.
- Brown noise is barely studied for sleep at all. Plenty of people like it; there’s little research either way.
None of this means noise is useless. It means the honest claim is smaller than “boosts deep sleep.”
The One Thing Noise Reliably Does: Masking
Here’s the effect that actually holds up. A steady background sound raises the floor so that sudden sounds — a car outside, a door, a snoring partner — don’t stand out sharply enough to wake you. Your brain reacts to abrupt changes in sound, and a constant hum smooths those changes over.
That’s why noise often helps light sleepers and people in noisy environments, and does little for someone in an already-quiet room. If your nights break up because of something disrupting you — noise, a partner, snoring — masking is a reasonable thing to try. If the disruption is internal, noise won’t fix it.
Snollo is a sleep tracking app for iPhone and Apple Watch. It includes a sound library with white, pink, brown, and blue noise you can layer into custom mixes, records audio overnight to detect snoring and noises that disrupt your rest, and reads sleep stages and heart rate from Apple Health. Your sleep data stays on your device and in your own iCloud. Snollo does not diagnose or treat any medical condition.
How to Use It Sensibly
- Pick by preference, not by color claims. If brown feels calming and white feels harsh, that preference matters more than any chart.
- Keep the volume low — just enough to cover disruptions. Louder isn’t better, and all-night loud sound carries a hearing and possibly a REM cost.
- Judge it by your own sleep. This is the part you can actually measure. Try a color for a few nights, then check whether your night had fewer disruptions — not whether a study said it should.
That last point is where tracking earns its keep. Snollo’s sound library — white, pink, brown, and blue noise, plus rain and ambient mixes you can layer and fade out on a sleep timer — is part of Snollo Premium. But the app is free to download, and it records your night and scores it on the free tier. So you can run your own test: play a sound one week, skip it the next, and see whether your disruptions and sleep score actually changed. Your data beats a headline.
To try it, download Snollo from the App Store and let tonight be the first night of your own experiment.