Pink Noise Disrupts Sleep Instead of Promoting It

By Irene Yeh 

February 13, 2026 | Pink noise, a type of broadband noise that sounds uniform and static-like, is often promoted as a tool for getting a restful night’s sleep. However, a recent study published in Sleep (DOI: 10.1093/sleep/zsag001) suggests that pink noise may have the opposite effect. Specifically, pink noise may negatively impact REM sleep, which can result in long-term neurological damage.  

How Noise Affected Sleep 

To determine pink noise’s effect on sleep quality, a team of researchers from the University of Pennsylvania Perelman School of Medicine had 25 participants partake in a randomized study. The participants were aged 21-41 years old and split into seven groups, each with up to four members. The study was performed over the course of seven nights in a sleep lab. Every morning, the participants filled out surveys, performed cognitive tests, and received cardiovascular measurements before going about their normal daily activities and returning to the lab in the evenings. The participants were also instructed not to nap, exercise, or drink alcohol during the day, as well as not allowed to consume caffeine after 3:00pm. 

There were six conditions that the groups were exposed to each night: control night without any noise exposure; environmental noise; pink noise at 50 decibels; environmental plus pink noise at 40 decibels; environmental plus pink noise at 50 decibels; and environmental plus participants wearing earplugs. The groups experienced every condition on different nights, but neither the participants nor the study staff were made aware of the sequence of noise conditions.  

The results showed that environmental noise only reduced slow-wave sleep and overall sleep depth, as well as increased EEG arousal, indicating greater sleep fragmentation. These results align with previous studies on traffic noises affecting sleep.  

However, perhaps the most prominent finding is pink noise’s effects on sleep. Pink noise at 50 dB did not increase sleep fragmentation or reduce sleep depth, but it reduced REM sleep. The team speculates that pink noise may activate auditory pathways that suppress neurons in the midbrain and hypothalamus, which play an important role in starting and maintaining REM sleep. As such, pink noise may make REM sleep more vulnerable when intermittent noise is present and delays the return of REM sleep even after the noises stop.  

Combining both environmental noise and pink noise resulted in worse sleep quality. Nights with environmental noise and pink noise showed less deep sleep and REM sleep, shorter total sleep time, lower sleep efficiency, and more time awake. Subjective assessments reported worse sleep quality, alertness, and mood, although not worse than with environmental noise alone. 

That said, pink noise did showcase some short-term benefits. When played with environmental noise, it reduced awakenings, brief EEG arousals, and overall sleep fragility with a dose-dependent reduction. However, these benefits were partly offset by increased sleep fragmentation during quiet periods.  

Earplugs were found to be the most effective. Wearing earplugs restored about 17-23 minutes of deep sleep that were lost to environmental noise—roughly a 72% reduction. Sleep structure, sleep quality, mood, and alertness with earplugs did not differ from nights without noise. Previous studies reported mixed results on earplug comfort and willingness to use them, but for this study, the participants generally found the earplugs comfortable and felt they slept better while wearing them. More research will be needed to determine if custom-fit or higher-quality earplugs could increase noise reduction and comfort. 

Limitations of the Study 

The study had a handful of limitations. The researchers initially recruited 27 participants. Two individuals withdrew on nights two and three, respectively, and were not included in the data analysis. One more participant withdrew on night five but was still included in the data analysis. This understandably might have influenced the results of the data analysis, especially because the sample size is quite small. Furthermore, most of the participants were young and healthy, so the findings of this study may not apply to younger, older, or non-healthy populations. Additionally, there were some nights when the noise systems would malfunction. Group 3, for example, had a system malfunction in three out of four subjects during night two, resulting in the research team having to replace night six with another control night. 

REM sleep duration increased over the course of the study. Since three of the six conditions included pink noise and pink noise reduced REM sleep, this increase may reflect a buildup of REM sleep pressure caused by selective REM sleep deprivation. In a different study of male college students, the results reported a rebound of REM sleep after three nights of white noise exposure to 93 A-weight decibels, suggesting REM sleep deprivation during exposure. However, the present study design cannot distinguish between REM sleep deprivation and habituation to pink noise. Further studies need to be conducted to clarify these effects. 

A key limitation of this study is the wide variation of sound exposure, including differences in noise type and sound pressure level for both EN events and broadband noise. EN events were also played at LAS, max levels of 45, 55, and 65 dB, but it is unclear how these findings apply to lower sound levels. Other broadband noises (e.g. white, blue, or brown) differ in their sound energy across the audible spectrum, and it is not feasible to test all combinations. An important step for future long-term field studies is to identify optimal noise color and level that best mitigate EN-related sleep disruption while providing maximum protection at the lowest possible sound level. 

The Crucial Role of REM Sleep 

Though the roles of REM sleep are still not fully understood, it is known to support memory, brain plasticity, and emotional regulation. Poor REM sleep has been linked to mental illnesses, such as depression, PTSD, and anxiety. Additionally, REM sleep behavior disorder is typically a prodromal biomarker for Parkinson’s and dementia with Lewy bodies, possibly due to impaired brain waste clearance.  

REM sleep is especially important for brain development and cortical maturation during the early stages of development. While there is little evidence on the effects of broadband noise on infant brain development, the results of this study indicate that these noises could cause more harm than benefits. The common practice of using broadband noise machines in bedrooms for newborns and toddlers may appear to improve sleep by reducing their naturally fragmented sleep, but this perceived benefit may be disrupting their REM sleep that is crucial to their neurodevelopment. More research needs to be done to fully understand the effects of broadband noise on early brain development in babies and children.