Millions of people fall asleep to a hum. A fan, a sound machine, a phone app playing rain or static.
So does white noise help you sleep? The research answer is surprisingly shaky.
It may help when your bedroom is noisy. But the evidence is weak, and one new lab study found a hidden cost.
- A review of 38 studies rated the evidence that steady noise improves sleep as very low quality.
- White noise seemed to help patients sleep in noisy hospital wards.
- A 2026 lab study found pink noise cut REM sleep, while earplugs blocked disruptive noise without that cost.
Does white noise help you sleep?
Maybe, if your problem is noise. There’s no good evidence that it helps people who already sleep in a quiet room.
White noise is a steady hiss that contains all sound frequencies at once. Pink noise is a softer, deeper version, more like steady rain.
The idea is masking. A constant background sound makes sudden noises, like a car door or a snoring partner, less jarring.
That makes sense in theory. But when scientists gathered all the studies, the results were all over the place.
What the research shows
The main review
The most thorough look is a 2021 systematic review in Sleep Medicine Reviews. Researchers at the University of Pennsylvania gathered every study of continuous white noise, or similar broadband noise, and sleep.
They found 38 studies. These measured how fast people fell asleep, how often they woke, how long they slept, and how well they felt they slept.
What it found
The results ranged widely, “with the extremes being that continuous noise improves or disrupts sleep”.
The studies differed in the noise used, how sleep was measured, and what people were compared with. That makes them hard to add up.
Using the standard GRADE system, the reviewers rated the evidence for noise improving sleep as very low. They noted this “contradicts its widespread use”.
They concluded that more research is needed “before promoting continuous noise as a sleep aid”. They warned it may also harm sleep and hearing.
After 38 studies, the evidence that white noise improves sleep is rated very low quality. It may help in noisy settings, but it isn’t a proven sleep aid.
Where white noise seems to help: hospitals
Hospitals are loud. Alarms, staff, machines and other patients make sleep hard.
A 2025 review in Sleep Medicine: X gathered randomised trials of sound machines for adults in hospital. It found seven trials with 496 patients.
Six of the seven used white noise. Together, they suggested masking noise improved sleep efficiency, meaning more of the time in bed was spent asleep.
White noise was well tolerated, and only 8 people stopped because of discomfort. But the studies were too different to combine in a meta-analysis.
| Setting | What the research suggests |
|---|---|
| Noisy hospital wards | White noise seems to improve sleep |
| A normal, quiet bedroom | No good evidence of benefit |
| A bedroom with outside noise | Earplugs worked better in one lab study |
| Infant sleep machines at full volume | Some may be loud enough to harm hearing |
The new twist: pink noise and REM sleep
The lab study
In 2026, a team including two of the review’s authors tested pink noise in a sleep lab. Twenty-five healthy adults spent seven nights there, with their sleep measured by brain monitoring.
On different nights, they slept with bursts of recorded environmental noise, pink noise, earplugs, or combinations. One night was silent for comparison.
What it found
The noise events cut deep sleep. Pink noise on its own cut REM sleep, the stage linked to dreaming, memory and mood.
Adding pink noise on top of the disruptive noise made overall sleep structure worse, not better. People also rated their sleep worse after pink noise nights.
Earplugs, by contrast, blocked nearly all the effects of the disruptive noise. They only started to fail at the loudest level.
The authors said the REM finding cautions “against the widespread and indiscriminate use” of broadband noise.
Why I’m careful with this one
It was a short study in 25 young, healthy adults. Morning thinking tests, heart measures and hearing weren’t affected.
So it doesn’t prove that sleeping with pink noise harms you long term. But it’s a reason not to assume the hum is harmless.
How loud is too loud?
Volume matters. A 2014 study in Pediatrics tested 14 infant sleep machines played at full volume.
At 30 cm, all 14 were louder than 50 dBA, the recommended limit for babies in hospital nurseries. Three topped 85 dBA.
That level, played for more than 8 hours, exceeds workplace noise limits for adults and risks hearing damage. The authors said these machines could harm infant hearing.
| Measure | Result |
|---|---|
| Machines tested | 14 |
| Louder than 50 dBA at 30 cm, at full volume | All 14 |
| Louder than 85 dBA | 3 |
The lesson applies to adults too. Keep any sound machine quiet and well away from your head.
What about sleeping with a fan?
Many people sleep with a fan, partly for the sound and partly for the breeze. Surprisingly, I couldn’t find any good trial that tested fans and sleep.
What we do know is that temperature matters. A review in the Journal of Physiological Anthropology found heat increases wakefulness and reduces deep sleep and REM sleep.
The NHS lists a room that’s too hot or cold, and noise, among the causes of insomnia. So a fan may help if it keeps you cool, but there’s no evidence on fan noise itself.
What earlier research found
Hospital patients
The 2025 hospital review is the strongest evidence that white noise can help. But its trials were small and measured sleep in different ways.
Older adults
A 2026 randomised trial in BMC Geriatrics gave 60 adults aged 65 and over white noise for 30 nights. Their sleep quality scores improved, while the comparison group’s didn’t change.
But both groups got sleep hygiene advice, the trial wasn’t blinded, and sleep was self-reported.
Traffic noise
A small 2026 study in Communications Medicine of 12 people found pink noise softened the effects of traffic noise on sleep. The authors said the results “should be interpreted cautiously”.
How it fits together
Steady noise may help when it’s covering up worse noise. Without that, the benefit is unproven, and there may be costs.
How much should you trust this?
Early. There are hints of benefit in noisy settings, but the evidence is weak and mixed.
What makes it convincing
- A careful systematic review covered 38 studies.
- Several hospital trials point the same way.
- The 2026 lab study measured sleep directly with brain monitoring.
What makes me cautious
- The main review rated the evidence very low quality.
- Studies used different sounds, volumes and measures.
- Most good results come from hospitals, not homes.
- The pink noise study was short and small.
- I couldn’t read the full text of the main review, only its summary.
| The evidence shows | The evidence does not show |
|---|---|
| White noise may help sleep in noisy hospitals | That it helps people in quiet bedrooms |
| Pink noise cut REM sleep in one lab study | That it causes long-term harm |
| Earplugs blocked noise well in the lab | That earplugs suit everyone |
| Some sound machines can get very loud | That normal-volume use damages hearing |
What this means for you
- Fix the noise first. The NHS advice is to make your bedroom dark and quiet, using earplugs if needed.
- Try earplugs before a sound machine. In the 2026 lab study, they protected sleep without cutting REM.
- If you use white noise, keep it low. Place the machine away from your bed, not next to your head.
- Be extra careful with babies. Keep infant sound machines quiet and well away from the cot.
- Keep the room cool. Heat disrupts sleep, so a fan may help for that reason.
- If it works for you and it’s quiet, there’s no need to panic. The evidence of harm is limited too.
The NHS guide to insomnia covers the basics of a good sleep routine. If you’re weighing supplements too, see what the trials found on whether magnesium helps you sleep.
In this video, Medscape looks at the new research on pink noise and sleep:
What we still don’t know
- Does white noise help people at home? Good trials in normal bedrooms are missing.
- Is pink noise really bad for REM sleep? One small study isn’t enough.
- What volume is safe for adults all night? There’s no clear answer yet.
- Do fans help or hurt sleep? No good trials exist.
- What about long-term use? Most studies lasted days or weeks.
My take: fine as a mask, not a miracle
What I like about this research is its honesty. The scientists who studied white noise most closely are the ones urging caution.
I’m less convinced by the idea that everyone should sleep with a hum. The best evidence comes from loud hospital wards, not quiet bedrooms.
If noise keeps you awake, earplugs are worth trying first. If white noise already helps you, keep it soft and away from your head.
Main source: Noise as a sleep aid: A systematic review (Sleep Medicine Reviews, 2021)
Last reviewed: 2026-10-03
Covers: Whether white noise helps you sleep, the evidence from hospitals, the 2026 pink noise study, safe volume and sleeping with a fan
Evidence: Early — very low-quality evidence overall, with some benefit in noisy settings
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