White Noise vs Pink Noise vs Brown Noise for Sleep

If you want a sound to fall asleep to, the color matters less than the volume. White noise has the only controlled trial in this research that showed better sleep. Continuous pink noise has the newest lab evidence against it. Brown noise has no sleep trial at all, only an argument about which frequencies it leaves out.

No study in this research compares the three colors head to head for sleep quality. So the practical answer is to try two or three colors at the lowest volume that covers the noise that wakes you, and keep whichever one you stop noticing.

The rest of this piece explains what separates the three signals, what each study tested, and why most of the good news about pink noise comes from something no sound machine does.

White noise spreads its energy evenly across every frequency you can hear. To the ear that makes it the brightest and hissiest of the three, closer to a fan or static than to rain.

It is also the color with the most direct trial behind it. A randomized trial published in BMC Geriatrics in May 2026 took 60 adults aged 65 and over, all poor sleepers. Both groups got standard sleep hygiene advice. Half also played white noise from a smartphone about 1 meter from the head, for 30 minutes a night over 30 nights, at an estimated 40 to 50 decibels.

Sleep quality was scored on the Pittsburgh Sleep Quality Index, a questionnaire where a lower score means better sleep. The white-noise group improved from 11.5 to 9.2. The control group barely moved, from 11.0 to 10.9. Time to fall asleep dropped by 10 minutes in the white-noise group and by 2 minutes in the controls.

The limits are real. It was 60 people, all over 65, and the sound played for only half an hour rather than all night. WebMD also cites an older study in which 38% of people fell asleep faster with white noise.

Who it suits: someone whose main problem is getting to sleep, who wants a timer-limited sound rather than one running until morning.

Pink noise keeps every frequency but tilts the energy toward the low end, so it sounds softer and deeper, like steady rain. It is the color with the most research, and that research points in two directions.

The cautionary result is the newest. In a study led by Mathias Basner at the University of Pennsylvania and published in Sleep in February 2026, 25 healthy adults aged 21 to 41 slept in a lab for seven nights. None of them normally used sound machines. Continuous pink noise at 50 decibels, about the level of moderate rainfall, cut REM sleep by nearly 19 minutes a night compared with silence. REM is the dreaming stage, which the researchers tie to memory and emotional regulation.

The study was funded to see whether pink noise could mask aircraft noise, and it could not. With aircraft noise plus pink noise, sleepers lost both deep and REM sleep and spent 15 more minutes awake. Earplugs, by contrast, blocked nearly all of the aircraft noise's effect on sleep.

The authors themselves list the limits: a small, young, healthy group, a lab rather than a bedroom, and one week of exposure. A critique from the Noise Foundation blog adds that the study used unfiltered, full-spectrum pink noise, and that people who have fallen asleep to a sound for years may respond differently from first-timers. That second point is an argument, not a finding.

The encouraging pink-noise studies mostly tested something else. A 2017 Northwestern study of 13 older adults found better next-day word recall, but the noise came as brief pulses synced to the sleeper's brain waves. A new MIT and Boston University study, reported by MIT News in September 2026, timed 50-millisecond bursts to the peaks of deep-sleep brain waves in 14 volunteers and boosted the flow of fluid that clears waste from the brain. Continuous or randomly timed pink noise did nothing comparable. Lead researcher Laura Lewis compared it to pushing a swing: the push only works at the right moment.

No home version of that timed technique exists. A sound machine playing pink noise all night is a different intervention, and the lab results do not carry over to it. TIME's review of the field describes the years since the first 2013 study as "mixed results."

Who it suits: someone who finds white noise too harsh and wants something between it and brown. Use it at a low volume and on a timer, not all night.

Brown noise, also called red noise, pushes the low end further still. The result is a rumble, closer to heavy rain on a roof or a rushing river than to a hiss.

No controlled sleep trial of brown noise appears in this research. The case for it rests on one idea from the Noise Foundation blog. Human hearing is most alert in the 1 to 4 kHz range. Pink noise still carries meaningful energy there, while brown noise carries very little. If the harm in the Penn study came from those middle frequencies, a bass-heavy sound might avoid it. Nobody has tested that, and a sleep-lab trial of brown noise against silence is what would settle it.

Who it suits: someone who finds white and pink noise too hissy to ignore, and who accepts that trying it is a personal experiment rather than a proven fix.

Line the studies up and color turns out to be the variable nobody isolated. The white-noise trial that helped played for 30 minutes at an estimated 40 to 50 decibels. The pink-noise trial that hurt ran all night at 50 decibels. The two also differ in age, country, and whether sleepers had trouble to begin with. The gap between them may have little to do with color.

So three things matter more than the label on the button.

How long it plays. The only positive trial used a short dose. The only negative one ran all night. A sleep timer is the cheapest way to stay on the side of the evidence.

How loud it is. Northwestern sleep physician Roneil Malkani advises keeping continuous background noise "just low enough to be audible, but not so high that it would cause arousal." WebMD cites CDC guidance that long exposure above 70 decibels can damage hearing. No study has yet looked at volumes below 40 decibels.

Whether you need it at all. Malkani says the people who benefit most are those sensitive to noise or living somewhere loud. If your problem is waking in the second half of the night rather than street noise, look first at causes like caffeine you think wore off. And if the noise is a real outside intrusion, the Penn study found earplugs did the job pink noise could not.

Since no trial picks a color for you, the useful machine is one that lets you switch colors and turn the volume down in fine steps.

The most rigorous published masking test comes from Reviewed. Its testers played party chatter, construction, barking dogs and crying babies at three volumes in a neighboring room. They then measured how loud each machine's white-noise setting had to be to cover them.

• The Adaptive Sound Sound + Sleep blocked every test noise at every level, with 30 sounds and a mode that adjusts volume to the room.
• The LectroFan matched it, masking all three levels of conversation without reaching unsafe volumes.
• The Snooz rarely needed to go past halfway to cover party noise, dogs or babies.
• The Dreamegg D1, the value pick, masked nearly everything by level 20 of its 32+ volume steps and offers 24 sounds.

Those figures measure masking with white noise only. They do not say how each machine's pink or brown setting sounds. None of the sources here publish masking figures for the Hatch Restore 3, the Magicteam Sound Machine or the Yogasleep Dohm Classic, so they cannot be ranked on the same test.

Whichever you choose, run each color for several nights at the lowest volume that covers your noise. Keep the one you stop hearing.

Start with white noise on a 30-minute timer, at a volume you can barely hear. It is the only color with a controlled trial showing better sleep, and that trial used exactly this pattern.

If the hiss keeps you awake, move to brown noise. It carries the least energy in the frequencies your ear watches most closely, though no one has tested it for sleep.

Be most cautious with all-night pink noise. It is the one color a sleep lab has measured cutting REM sleep. The impressive pink-noise results you may have read about came from timed bursts in a lab, not from anything you can buy.

If the noise you are fighting is loud and outside your control, try earplugs before any color.