Guide · 3 min read
White, pink or brown noise for sleep? What the evidence says
Searches for brown noise have exploded. The science is quieter than the hype. Here's what each colour of noise is, what it can and can't do, and how to use it if you like it.
White, pink and brown noise are steady sounds that differ in how much of their energy sits in low versus high pitches. Brown is the deepest and softest; white is the hissiest.
A 2021 systematic review rated the evidence that continuous noise improves sleep as very low quality, and a 2026 lab study found pink noise reduced REM sleep. Steady sound can help mask disruptive noise in a loud bedroom. If you use it, keep it quiet and put it on a timer. Earplugs are worth trying first.
White vs pink vs brown noise
All three are "broadband" noise: a steady mix of many frequencies at once, like a hiss, a rush or a rumble. The colours describe the balance.
| Noise | What it sounds like | How it's built |
|---|---|---|
| White | A bright hiss, like TV static or a fan on high | Equal energy at every frequency, so the high end stands out |
| Pink | Softer, like steady rain or wind in trees | Energy falls as pitch rises, so it's more balanced to the ear |
| Brown | A deep rumble, like a distant waterfall or the inside of a plane | Energy falls even faster with pitch, leaving mostly low tones |
Many people find brown noise the most pleasant because it has the least hiss. That's a matter of taste, not evidence that it's better for sleep.
What the research actually found
In 2021, sleep researchers at the University of Pennsylvania reviewed 38 studies on continuous noise and sleep. The studies varied a lot, and the results ran in both directions: some found noise helped, some found it disrupted sleep. Using standard grading, they rated the evidence that continuous noise improves sleep as very low quality, and they cautioned that it might also harm sleep and hearing.
In 2026 the same group published a sleep-lab study of 25 healthy adults in the journal SLEEP. Playing pink noise through the night didn't change deep sleep, but it reduced REM sleep by about 19 minutes on average. Disruptive environmental noise, like aircraft, cut deep sleep by about 23 minutes. Simple foam earplugs won back around 72% of that lost deep sleep, with no effect on REM. The study was small, short and in young healthy sleepers, so it isn't the final word, but it's a reason not to treat noise as harmless.
There are almost no good studies of brown noise specifically. Its popularity comes from social media, not sleep labs.
When noise can help
Steady sound is mainly useful as a mask. Sudden noises (a door, a car, a partner's snore) wake you because they stand out against silence. A steady background makes the jumps smaller. That can genuinely help if you live on a busy street, share a room, or work nights and sleep in the day.
It can also become part of a wind-down routine: a familiar sound that signals bedtime. That's a habit effect, and it's real, whatever the colour of the noise.
How to use it safely
- Try earplugs first if noise is waking you. In the 2026 study they protected most of the deep sleep that noise took away, without the REM cost.
- Keep it quiet. Just loud enough to blur other sounds, well below conversation level. Put the speaker across the room, not by your head.
- Use a timer. If it helps you fall asleep, let it fade out after 30 to 60 minutes rather than playing all night.
- Be careful with babies. Infants spend much more of their sleep in REM. Don't run noise machines loud or close to a cot.
- Prefer gentler sounds if you're using it to relax rather than to mask: slow music, rain, or a quiet fan.
The app's sounds are generated on your phone and work offline: rain, ocean, a fan, warm music and brown, pink and soft "green" noise. Every sound has a sleep timer, and we don't claim that any of them changes your brain waves or sleep stages, because the evidence isn't there.
Sources
- Noise as a sleep aid: a systematic review (Riedy, Smith, Rocha & Basner, 2021), Sleep Medicine Reviews
- Pink noise and earplugs under environmental noise: a sleep-lab study (Basner et al., 2026), SLEEP
- Pink noise, a popular sleep aid, could disrupt sleep quality, study suggests, The Detroit News
- White noise (and pink and brown): the science behind the sounds, CNN Health