White, pink and brown noise for sleep: what the research says (2026 update)
- Steady sound masks sudden noise, which is why many people fall asleep more easily with a fan on.
- Evidence that it improves sleep overall is weak, and a 2026 Penn sleep-lab trial found all-night pink noise at 40 to 50 dBA reduced REM sleep in people not used to it.
- Earplugs beat noise for blocking traffic and aircraft noise in that trial.
- Practical takeaway: keep the volume low, keep the speaker away from your head, and use a sleep timer so the sound stops after you fall asleep.
I make a box fan sound app, so I have an obvious interest in this topic. That's exactly why this page sticks to what studies actually found, including the findings that don't flatter sleep sounds. Every study is linked at the end so you can check it yourself.
The big 2026 study: pink noise, traffic noise and earplugs
In February 2026, researchers at the University of Pennsylvania Perelman School of Medicine published one of the most careful tests of sleep sounds so far in the journal SLEEP. Twenty-five healthy adults aged 21 to 41 spent seven nights in a sleep lab with full sleep monitoring. On different nights they slept in quiet, with recorded traffic and aircraft noise, with continuous pink noise, with both, and with foam earplugs.
- Traffic and aircraft noise cut deep (N3) sleep by about 23 minutes per night.
- Pink noise on its own reduced REM sleep by about 19 minutes per night at the louder setting, and the effect grew with volume.
- Pink noise added to traffic noise did not rescue sleep. Deep sleep and REM were both shorter and people spent about 15 more minutes awake.
- Foam earplugs restored most of the deep sleep lost to traffic noise, and most sleep measures looked close to quiet nights.
- People felt their sleep was lighter and worse with noise, but morning test scores did not change significantly.
What this study does not tell us
- It excluded people who already sleep with sound, so it can't say how long-time fan sleepers are affected.
- It ran for one week in young, healthy adults, at two volumes of one sound (pink noise). It did not test fan recordings, brown noise or quieter levels.
- The authors themselves called for more research on long-term use, other noise colors and safe levels.
All the key studies at a glance
Basner et al., SLEEP (University of Pennsylvania)
Tested: 25 healthy adults, 7 nights in a sleep lab. Compared quiet nights, traffic/aircraft noise, continuous pink noise at 40 and 50 dBA, both together, and foam earplugs.
Found: Pink noise alone reduced REM sleep by about 19 minutes per night (louder level). Traffic noise cut deep sleep by about 23 minutes. Pink noise on top of traffic noise made overall sleep worse, not better. Earplugs restored most of the lost deep sleep.
Wunderlin et al., Frontiers in Sleep
Tested: 16 older adults. Very short pink-noise pulses played in time with deep-sleep brain waves, over three nights.
Found: Boosted deep-sleep brain activity; memory gains appeared after several nights but did not last at follow-up. This is a lab technique, not all-night sound.
Capezuti et al., Journal of Clinical Sleep Medicine
Tested: Systematic review of 34 studies on white noise, pink noise and mixed sound.
Found: About half the studies reported better sleep, more often with pink noise than white noise, but evidence was low quality and not strong overall. No harms reported from short-term use.
Riedy et al., Sleep Medicine Reviews
Tested: Systematic review of 38 studies on continuous noise as a sleep aid.
Found: Evidence that continuous noise improves sleep was rated very low quality. Some studies found faster sleep onset; at least one found more disrupted sleep.
Hugh et al., Pediatrics
Tested: 14 infant sleep sound machines measured at full volume, 30 to 200 cm away.
Found: All could exceed 50 dB; three exceeded 85 dB at 30 cm (crib-rail distance). Authors urged low volume and short use.
Coleman-Phox et al., Archives of Pediatrics & Adolescent Medicine
Tested: 185 infants who died of SIDS compared with 312 controls (interview-based).
Found: Fan use in the room was associated with 72% lower SIDS risk. The proposed reason is air circulation, not sound, and it is an association, not proof.
Why a steady sound still helps many people fall asleep
Most awakenings from noise come from changes in sound, like a door slam, a passing car or a voice, rather than from the overall loudness. A steady background sound makes those changes smaller relative to the background, so they are less likely to stand out. That masking effect is real, and it is why so many people, including the writer of this page, keep a fan running even in winter.
The research above suggests the trade-off: the masking helps most while you are falling asleep, while all-night sound at a meaningful volume may cost some REM sleep. REM sleep is concentrated in the second half of the night, which is a reason to let the sound fade out once you are asleep.
How to use sleep sounds sensibly, based on the research
- Use the lowest volume that works. In the Penn trial, the REM effect grew from 40 to 50 dBA. 50 dBA is roughly a quiet conversation; aim well below what you would talk over.
- Keep the speaker away from your head. Put your phone on a nightstand or across the room, not on your pillow.
- Use a sleep timer. Let the sound cover the time it takes you to fall asleep, then fade out. In Box Fan Sleep, the 15 and 30 minute timers are free and fade out gradually.
- For outside noise, try earplugs. They outperformed pink noise against traffic noise. Some people combine soft earplugs with a quiet fan sound while falling asleep.
- Prefer what feels comfortable. There is no evidence that one noise color is best for everyone. Many people find brown or a low fan tone less harsh than white noise.
- Be extra careful with babies. See below.
Where Box Fan Sleep fits
Box Fan Sleep is built for people who already like falling asleep to a fan. Based on the research above, here is how to set it up:
- Pick the tone you find calmest. Brown and pink are softer than white.
- Set your phone volume low and put the phone a few feet away.
- Start a 15 or 30 minute timer so the sound fades once you're asleep.
Box Fan Sleep is not a medical device and doesn't treat any sleep disorder. If you regularly struggle to sleep, talk to a doctor; cognitive behavioral therapy for insomnia (CBT-I) has much stronger evidence than any sound.
Frequently asked questions
Is it bad to sleep with pink noise or white noise all night?
A 2026 sleep-lab trial from the University of Pennsylvania found that pink noise played all night at 40 to 50 dBA reduced REM sleep in healthy young adults who did not normally sleep with sound, by about 19 minutes per night at the louder level. It was a short study in 25 people, so it does not settle the question, but it is a good reason to keep the volume low and to use a sleep timer rather than playing sound all night.
Do earplugs or white noise work better against traffic noise?
In the same 2026 trial, foam earplugs protected deep sleep against simulated traffic and aircraft noise much better than pink noise did, bringing most sleep measures close to quiet nights. If outside noise is your main problem and you can sleep with earplugs, they are worth trying first.
Does pink noise improve memory during sleep?
Only in a specific lab setup. Studies that play very short pulses of pink noise timed to deep-sleep brain waves have found improvements in deep-sleep activity and, in some studies, memory. That technique uses EEG equipment and is not the same as playing a continuous sound all night.
Is white noise safe for babies?
Use caution. The American Academy of Pediatrics recommends keeping sound for infants below 50 dB, the machine at least two feet from the crib, and turning it off once the baby is asleep. Researchers behind the 2026 Penn trial also cautioned against broadband noise for newborns and toddlers, because REM sleep matters for brain development, though they did not test children.
Why do people sleep better with a fan on, then?
Steady sound makes sudden noises stand out less, which is why it can help when you are falling asleep in a noisy place, and many people find a familiar sound comforting. The 2026 trial excluded people who already sleep with sound, so it does not tell us how long-time fan sleepers are affected.
Sources
- Basner M, Smith MG, Cordoza M, et al. Efficacy of pink noise and earplugs as countermeasures against environmental noise-induced sleep disruption. SLEEP. 2026. doi:10.1093/sleep/zsag001. Press summary: ScienceDaily.
- Garcia Molina G. Protecting sleep in a noisy world (editorial). SLEEP. 2026;49(5):zsag032. academic.oup.com
- Wunderlin M, Zeller CJ, Wicki K, Nissen C, Züst MA. Acoustic stimulation during slow wave sleep shows delayed effects on memory performance in older adults. Frontiers in Sleep. 2024;2:1294957. doi:10.3389/frsle.2023.1294957
- Capezuti E, Pain K, Alamag E, Chen X, Philibert V, Krieger AC. Systematic review: auditory stimulation and sleep. J Clin Sleep Med. 2022;18(6):1697–1709. doi:10.5664/jcsm.9860
- Riedy SM, Smith MG, Rocha S, Basner M. Noise as a sleep aid: a systematic review. Sleep Med Rev. 2021;55:101385. doi:10.1016/j.smrv.2020.101385
- Hugh SC, et al. Infant sleep machines and hazardous sound pressure levels. Pediatrics. 2014. Summary: Science News.
- Coleman-Phox K, Odouli R, Li DK. Use of a fan during sleep and the risk of sudden infant death syndrome. Arch Pediatr Adolesc Med. 2008;162(10):963–968. Summary: ScienceDaily.
- Infant sound machine guidance (AAP recommendations): Children's National Hospital.
A fan sound, used sensibly
Low volume, a fade-out timer, and the tone you find calmest. Free on iPhone and iPad.