A small sleep-lab study from the University of Pennsylvania reports that continuous “pink noise” played overnight reduced participants’ REM sleep, while earplugs helped blunt deep-sleep losses linked to intermittent aircraft noise. The findings add to a limited evidence base about the long-term effects of broadband “sleep sounds,” and the researchers urge caution—particularly for young children.
A sleep-laboratory study from the University of Pennsylvania Perelman School of Medicine, published in the journal Sleep, tested whether continuous “pink noise” or earplugs could mitigate the effects of intermittent environmental noise during sleep.
Researchers monitored 25 healthy adults ages 21 to 41 over seven consecutive nights, with eight-hour sleep opportunities each night. Participants reported no sleep disorders and said they did not typically use sound to help them sleep.
Across different nights, participants were exposed to several conditions: aircraft noise, pink noise alone, aircraft noise combined with pink noise, and aircraft noise while wearing earplugs.
Compared with noise-free control nights, aircraft noise was associated with about 23 fewer minutes per night in N3 sleep, the deepest stage of non-REM sleep. The researchers said earplugs largely prevented that deep-sleep reduction.
The study also found that pink noise played at 50 decibels—a level the researchers compared to moderate rainfall—was associated with a nearly 19-minute decrease in REM sleep when played on its own.
When pink noise was combined with aircraft noise, both deep sleep and REM sleep were shorter than on control nights, and participants spent about 15 additional minutes awake during the night—an increase the researchers said was not seen with aircraft noise alone or pink noise alone.
Participants also reported that their sleep felt lighter, that they woke more often, and that their overall sleep quality was worse on nights with aircraft noise or pink noise—effects the researchers said were largely absent when earplugs were used.
“REM sleep is important for memory consolidation, emotional regulation and brain development, so our findings suggest that playing pink noise and other types of broadband noise during sleep could be harmful—especially for children whose brains are still developing and who spend much more time in REM sleep than adults,” said study lead author Mathias Basner, MD, PhD, a professor of Sleep and Chronobiology in Psychiatry at Penn.
The researchers pointed to the widespread popularity of “sleep sounds.” They cited platform metrics indicating that white noise and ambient podcasts account for about three million hours of daily listening on Spotify, and that the top five YouTube videos returned for the search term “white noise” have together accumulated more than 700 million views. They also said up to 16% of Americans use earplugs to help them sleep.
Basner said the team’s results support earplugs as a practical way to reduce the sleep-disrupting effects of intermittent environmental noise, while underscoring the need for more data on broadband noise used as a sleep aid.
“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,” Basner said.
Penn said the research was funded by the U.S. Federal Aviation Administration (FAA) Office of Environment and Energy through the FAA’s ASCENT program.
