Millions of people rely on a sleep aid to get their nightly Zs, but research shows that commonly used noise machines do more harm than good.
While many people use the steady hum of pink noise to drown out background noise and facilitate sleep, a study found that adding pink noise to a noisy environment had a counterproductive effect.
Researchers from the University of Pennsylvania Perelman School of Medicine found that healthy adults who listened to pink noise, a deep, steady sound similar to rainfall or a waterfall, lost 19 minutes of sleep in a crucial part of the cycle.
Pink noise, like the very popular white noise, is a type of broadband noise characterized by continuous, uniform, and static-like signals spanning a wide range of audible frequencies.
Most of the 25 adults in the study reported feeling that their sleep was lighter, more frequently interrupted and of poorer overall quality after nights exposed to pink noise. When pink noise was combined with airplane noise, they felt the combination of both was the most disruptive condition of all.
More than 16 percent of Americans – about 53 million people – use noise machines to fall asleep every night, and three million hours of white noise are streamed daily on Spotify alone, with top YouTube noise videos garnering over 700 million views.
Disrupting deep sleep, the period of the sleep cycle in which the brain clears toxins and consolidates memories, as well as REM sleep, the dreaming phase, is associated with higher rates of depression, anxiety, injuries and accidents, Parkinson’s disease and loss of productivity.
Sleep researchers at the University of Pennsylvania found that exposure to airplane noise cost healthy adults roughly 20 minutes of essential REM and Deep sleep per night (stock)
Twenty-five healthy adults ages 21 to 41 participated in a sleep study, published in the journal Sleep, in which they slept in a lab for eight hours a night over seven consecutive nights. None were regular users of sound machines or had sleep disorders.
Researchers tested their sleep under various conditions, including exposure to aircraft noise, pink noise, and a combination of both, as well as aircraft noise while wearing earplugs.
Each morning, participants completed tests and surveys to measure sleep quality, alertness, and health effects.
When exposed to aircraft noise alone, people reported that their sleep felt lighter and more fragmented and they rated their overall sleep quality as worse than on quiet nights.
Pink noise alone similarly led to reports of poorer sleep quality.
Notably, the combination of aircraft and pink noise was judged by participants to be the worst condition.
They felt their sleep was significantly lighter, reported waking up more frequently and gave it the lowest overall quality rating.
Meanwhile, nights with aircraft noise while using earplugs were perceived much more positively. Participants reported that earplugs effectively muffled the disruptive sounds, making their sleep feel deeper, less interrupted and almost as good as a quiet, restful night without background noise.
The impact of different noise conditions on deep (N3) sleep. CTRL (quiet baseline, gray) is compared to EN (aircraft noise, blue), EN+NP40 (aircraft plus pink noise at 40 decibels, pink), EN+PN50 (aircraft plus pink noise at 50 decibels, purple) and EN+EP (aircraft noise with earplugs, green). Aircraft noise significantly reduced deep sleep, an effect worsened when combined with pink noise but prevented by earplugs
The impact of different noise conditions on REM sleep. Pink noise, particularly at 50 decibels (purple), significantly reduced REM sleep, an effect distinct from the deep sleep disruption caused by aircraft noise alone (blue in figure D)
These subjective reports were strongly supported by the objective laboratory data. Exposure to aircraft noise alone reduced deep, restorative sleep by approximately 23 minutes per night.
While pink noise did not significantly impact deep sleep, it had a detrimental effect on dreaming REM sleep, reducing it by nearly 19 minutes.
The combined condition of aircraft noise and pink noise was particularly harmful, significantly reducing both deep and REM sleep while also increasing time awake by 15 minutes. WEARING earplugs, however, proved highly effective at protecting against noise.
It largely prevented the loss of deep sleep caused by aircraft noise, demonstrating that it is the most reliable method for safeguarding sleep against disruptive noise pollution.
Study lead author and sleep expert Dr Mathias Basner said: ‘Overall, our results caution against the use of broadband noise, especially for newborns and toddlers, and indicate that we need more research in vulnerable populations, on long-term use, on the different colors of broadband noise, and on safe broadband noise levels in relation to sleep.’
Bad sleep directly undermines physical health by weakening the immune system and elevating the risk of heart disease, diabetes and obesity.
During deep sleep, the brain clears toxins linked to neurodegenerative diseases like Alzheimer’s. Losing this stage disrupts a vital restorative process.
Mentally, poor sleep impairs cognitive function, hurting memory, focus and judgment, and destabilizes emotional regulation, heightening vulnerability to stress, anxiety and depression.
When sleep is disrupted by environmental factors like noise, the harm is compounded if the intended solution backfires.
This means that in seeking relief, individuals may unknowingly deprive themselves of the very sleep stages most essential for brain restoration and long-term health, turning a common coping strategy into a contributor to potentially deadly health problems.
