Updated
White noise and other steady sounds can help some people fall asleep by covering up the noises that wake them, such as traffic, a snoring partner, or a neighbor's door. The evidence that it improves sleep for everyone is weak, so think of it as a tool for a noisy room rather than a sleep treatment. If you use it, keep the volume low, keep the source away from your head, and choose a sound you find easy to ignore.
Pink and brown noise are variations that put more weight on low frequencies, so they sound deeper and softer than the hiss of white noise. Many people find them more pleasant. None of the three has been shown to beat the others for sleep, so the right choice is the one you can stop noticing.
What white, pink, and brown noise are
All three are steady, random sounds with no rhythm or melody. The difference is how the energy is spread between high and low pitches.
- White noise has equal energy across all frequencies. To the ear it sounds bright and hissy, like an untuned radio or a shower running hard.
- Pink noise has less energy in the high frequencies, so it sounds fuller and softer. People compare it to steady rain or wind in trees.
- Brown noise, sometimes called red noise, drops off even more steeply at the top end. It is a deep rumble, closer to a distant waterfall or the inside of an airplane cabin.
Fan sounds, rain, ocean waves, and train hum are everyday cousins of these. They are not perfectly steady, but they do the same basic job.
Why steady sound can help
The idea behind white noise is masking. You are rarely woken by sound alone. You are woken by a change in sound, such as a car door after a quiet street or a dog barking into silence. A steady background raises the baseline, so those sudden changes stand out less.
That is why sleep sounds help most in rooms with unpredictable noise: city apartments, shared bedrooms, hotels, and trains. In a room that is already quiet, they have much less to do.
What the research actually shows
The research is thinner than the popularity of white noise suggests.
In 2021, Samantha Riedy and colleagues published a systematic review in Sleep Medicine Reviews that looked at 38 studies of continuous noise and sleep. Using the standard GRADE criteria, they rated the quality of evidence that continuous noise improves sleep as very low. Results ranged from improved to more disrupted sleep, and the studies varied widely in the sounds they used, how they measured sleep, and who took part.
You may also have seen headlines linking pink noise to deeper sleep or better memory. Those mostly come from lab studies, such as a 2013 study by Ngo and colleagues in the journal Neuron, where short bursts of sound were timed precisely to a sleeper's brain waves using live recordings. A track playing on a loop all night is a different thing, and those results do not carry over to it.
The fair reading: steady sound is a reasonable thing to try if noise is what keeps you up, it seems harmless for most adults at sensible volumes, and it is not something to expect a big change from if your room is already quiet.
How to use sleep sounds well
Keep the volume low. Set it just loud enough to blur the noises you want to cover, and no louder. If you have to raise your voice to talk over it, it is too loud. Very loud sound for hours is a hearing concern, not just a sleep one.
Put the source away from your head. A phone or speaker on the far side of the room or the end of the bed is better than one next to your pillow. Sound drops quickly with distance.
Pick a sound you stop hearing. Some people find white noise grating and brown noise soothing, others the opposite. Try each for a few nights. Avoid sounds with sudden events, such as a single thunderclap or a bird call, if they tend to wake you.
Choose between a timer and all night. If you only struggle to fall asleep, a timer of 30 to 60 minutes may be all you need. If your trouble is being woken in the small hours, sound that runs through the night makes more sense. Either is fine. What matters is what the sound is covering.
Be careful with headphones and earbuds. Sleeping in earbuds can be uncomfortable, and the volume sits right in your ear. If you use them, keep the level very low. Also note that if earbuds or a Bluetooth speaker are still connected in the morning, your alarm may play there instead of the phone. See why your alarm plays through AirPods.
Keep your alarm loud enough to cut through. A sound that masks traffic can also mask a quiet alarm. If you leave sleep sounds running all night, make sure your alarm volume is set well above them, or that the sound stops before the alarm.
A note on babies
Sound machines are popular for infants, and here volume and distance matter even more. A 2014 study in Pediatrics by Hugh and colleagues tested 14 infant sleep machines at maximum volume. At 30 centimeters every one of them was louder than 50 A weighted decibels, the recommended noise limit for hospital nurseries, and three produced more than 85 decibels, a level that would exceed adult workplace limits over an eight hour shift. The study measured maximum output, not how parents actually use the machines, but the lesson is simple: keep the machine across the room from the crib and the volume low, and ask your pediatrician if you have questions.
When sound is not the answer
If you sleep badly in a quiet room, or wake most nights for reasons that have nothing to do with noise, a sound machine is unlikely to change much. Long stretches of poor sleep are worth raising with a doctor. Earplugs are also worth a try for noise problems, since they lower sound rather than adding more.
Sleep sounds in Snora
Snora has 14 sleep sounds, including White noise, Pink noise, Brown noise, Fan, Rain, Ocean, Stream, Distant thunder, and Train hum, and they keep playing with the screen off. All 14 are free, as are alarms and sleep tracking, and you do not need an account.
FAQ
Does white noise help you sleep?
It can help some people, mainly by masking sudden noises in a noisy room. A 2021 systematic review of 38 studies rated the evidence that continuous noise improves sleep as very low quality, with mixed results. It is worth trying if noise wakes you, but it is not a proven sleep aid for everyone.
What is the difference between white, pink, and brown noise?
White noise has equal energy at all frequencies and sounds bright and hissy. Pink noise has less high frequency energy and sounds like steady rain. Brown noise drops off even more at the top and sounds like a low rumble. Research has not shown one to be better for sleep, so pick the one you find easiest to ignore.
Is it bad to sleep with white noise all night?
For most adults it is fine at a low volume with the source a little way from your head. Keep it just loud enough to cover background noise. If you only have trouble falling asleep, a timer may be enough. Make sure your morning alarm is loud enough to be heard over it.
How loud should white noise be for sleep?
As quiet as you can set it while still covering the noise that bothers you. A good test is that you can talk over it in a normal speaking voice. For babies, keep the machine across the room and the volume low, since a 2014 Pediatrics study found infant sleep machines at maximum volume were louder than hospital nursery limits.