February 03, 2026
Polina/Pexels.com
Apps that play broadband noise, such as continuous rainfall or wind sounds, may disrupt restorative REM sleep, Penn Medicine research suggests.
It's common for people to play continuous wave sounds and other gentle nature noises on their phones to lull themselves to sleep. But this type of "pink noise" may actually be backfiring, a new Penn Medicine study suggests.
The Sleep Foundation's definition of pink noise is a bit technical: "noise frequencies that decrease in power with each higher octave to create a lower pitch." But it's often compared to nature sounds like steady rainfall, wind or waves.
Health experts sometimes prescribe pink noise for people who have trouble sleeping or to promote relaxation, because it has been found to be more gentle than white noise, which has a higher pitch and sounds similar to static from an untuned radio or TV.
But researchers from the University of Pennsylvania found pink noise interferes with restorative rapid eye movement (REM) sleep and sleep recovery. Wearing earplugs is a more effective way to block out traffic noise, the study found.
"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 Dr. Mathias Basner, the study's lead author.
For the study, published Monday in the journal Sleep, researchers had 25 adults spend their nights for an entire week in a sleep lab. The participants were not in the habit of using noise to help them sleep and had no sleep disorders.
The researchers exposed the participants to aircraft noise, pink noise, aircraft noise with pink noise and aircraft noise with earplugs. Researchers then used different methods each morning to test the participants' sleep quality, alertness and other health effects.
They found exposure to aircraft noise overnight led to a 23-minute drop in the deepest stage of REM sleep, but wearing earplugs essentially blocked out the air traffic sounds.
Pink noise by itself, equivalent to "moderate rainfall," was linked to a loss of 19 minutes of REM sleep. And pink noise combined with aircraft noise led to "significantly shorter" time spent in deep sleep and REM sleep compared to nights without any type of noise.
Participants also reported that their sleep felt lighter, that they woke up more frequently throughout the night and that their overall quality of sleep was worse when they were exposed to aircraft or pink noise. But using earplugs against pink noise and aircraft noise improved their overall quality of sleep.
The effects of pink noise, white noise and other types of broadband noise — used by 16% of Americans at night — need further study, the researchers concluded.
"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.
