Many people use sound machines or apps that play pink noise to help them sleep better. But new research from the University of Pennsylvania suggests that pink noise may actually reduce important sleep stages—especially REM sleep—and may not be as safe as once thought. On the other hand, using earplugs to block out noise seems to protect sleep better.
The study was published in the journal SLEEP and challenges the growing trend of using ambient sounds like pink noise to fall asleep.
The lead author, Dr. Mathias Basner, explained that REM sleep is very important for memory, emotional balance, and brain development. Reducing REM sleep, especially in children who spend more time in it than adults, could be harmful.
In the study, researchers observed 25 healthy adults aged 21 to 41 for seven nights in a sleep lab. The participants had no history of sleep problems and didn’t usually use noise to help them sleep.
Each night, they were exposed to different sound conditions, including aircraft noise, pink noise, both combined, and no noise at all. They also tried sleeping with earplugs while exposed to aircraft noise.
Every morning, participants took tests and answered questions about how well they slept and how alert they felt. The results showed that aircraft noise reduced the deepest stage of sleep (called N3) by about 23 minutes. However, wearing earplugs helped protect against this loss.
Pink noise alone—played at a volume similar to gentle rain—reduced REM sleep by almost 19 minutes. When pink noise and aircraft noise were played together, both deep sleep and REM sleep were reduced, and participants spent 15 extra minutes awake during the night.
People also said their sleep felt lighter, and they woke up more often. But when they used earplugs, they slept better, even with aircraft noise.
Pink noise is a type of broadband noise. It sounds like soft static and includes sounds spread across many different frequencies. Other types of broadband noise include white noise, brown noise, and even natural sounds like ocean waves or rainfall.
These sounds are popular in apps, podcasts, and YouTube videos. For example, white noise and ambient sound content make up millions of listening hours each day, yet there is not enough research on how these sounds actually affect sleep.
One of the main concerns is that REM sleep is often disrupted in people with mental health issues like depression and anxiety. Since young children spend more time in REM sleep than adults, they may be even more at risk. Despite this, many parents place white noise machines near their babies or toddlers, hoping to help them sleep better.
Dr. Basner emphasized the need for more research, especially in vulnerable groups like young children. He said we need to understand the long-term effects of different types of broadband noise, what noise levels are safe, and whether these sounds are helpful or harmful.
The key takeaway is that while pink noise might help some people fall asleep, it could also interfere with the quality of sleep—especially the important REM stage. If you’re trying to block out unwanted noise, earplugs might be a safer and more effective choice.
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