A new study from the University of Pennsylvania Perelman School of Medicine reports that playing pink noise during sleep may reduce restorative REM sleep and interfere with overall sleep recovery. The research, published in the journal Sleep, also found that earplugs are significantly more effective at protecting sleep from traffic noise.
The study observed 25 healthy adults aged 21 to 41 in a sleep laboratory for seven consecutive nights. None of the participants reported using noise to help them sleep or having any diagnosed sleep disorders. Participants experienced different sleeping conditions, including exposure to aircraft noise, pink noise, aircraft noise combined with pink noise, and aircraft noise with earplugs. Each morning, they completed tests and surveys assessing their sleep quality, alertness, and health effects.
The researchers explained the importance of deep (N3) and REM sleep. Deep sleep supports physical restoration and memory consolidation, while REM sleep is crucial for emotional regulation and brain development.
Pink noise is a type of broadband sound spread across various frequencies and sounds static-like. Other types of broadband noises include white, brown, and blue noises; many household appliances also produce similar sounds.
Results showed that exposure to aircraft noise led to about 23 fewer minutes per night in deep N3 sleep compared to quiet nights. Earplugs helped prevent much of this reduction in deep sleep. Pink noise alone at 50 decibels resulted in nearly 19 minutes less REM sleep. When both pink and aircraft noises were present, both deep and REM stages were shorter than on control nights without added sounds; participants also spent an additional 15 minutes awake.
Participants noted lighter overall sleep quality when exposed to either aircraft or pink noises unless they used earplugs.
Researchers said these findings highlight not only the likely effectiveness of earplugs—used by up to 16 percent of Americans—but also the need for more comprehensive studies on pink noise "sleep aids." Millions use broadband sounds every night through apps or online platforms such as Spotify or YouTube for better rest; however, current research on their impact remains limited.
Disruption in REM sleep is commonly linked with conditions like depression, anxiety, and Parkinson’s disease. Study author Mathias Basner pointed out that young children spend more time in REM than adults do: "Basner noted that young children, compared to adults, spend much more time in REM sleep-and thus may be particularly vulnerable to the ill effects of pink noise."
He added: "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."
The study was funded by the U.S. Federal Aviation Administration Office of Environment and Energy through ASCENT.
