Are Sound Machines Improving Your Sleep or Making It Worse?

• A recent study suggests that pink noise, often used in sound machines, may interfere with REM sleep.
• This interference can interrupt sleep recovery and reduce overall sleep quality.
• The study authors say that using earplugs may be an effective alternative to pink noise.

Pink noise is a constant, soothing sound that contains all the frequencies humans can hear.

It’s often compared to natural sounds, like rain, the rustling of leaves, or a waterfall. People often use pink noise in sound machines or apps to mask other noise, sharpen focus, and promote a deeper sleep.

However, a recent study published in the journal Sleep suggests that using pink noise may disrupt restorative rapid eye movement (REM) sleep and interfere with sleep recovery.

REM sleep is an active stage of sleep that involves high brain activity, vivid dreaming, increased heart rate, and temporary paralysis. A disrupted REM cycle can affect your mental health, your ability to learn, and your memory.

“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,” lead study author Mathias Basner, MD, PhD, professor of psychiatry at the University of Pennsylvania Perelman School of Medicine, said in a press release.

The study observed 25 healthy adults ages 21 to 41. The observations were conducted in a sleep laboratory during 8-hour sleep opportunities over the course of seven consecutive nights.

The study participants reported not having used noise to help them sleep or having a sleep disorder. They slept under various conditions, including:

• exposure to airplane noise
• use of pink noise
• exposure to both airplane noise and pink noise
• exposure to airplane noise while using earplugs

Each morning, participants completed surveys and tests to assess sleep quality, alertness, and other health outcomes.

Exposure to aircraft noise, compared to no noise, was associated with around 23 fewer minutes spent in the deepest stage of sleep. Earplugs helped to prevent this drop in deep sleep to a large extent.

Pink noise alone, at 50 decibels, was associated with a nearly 19-minute decrease in REM sleep. This level of pink noise is often compared to the sound of moderate rainfall.

When pink noise was combined with airplane noise, both REM and deep sleep were disturbed compared to control nights with no noise. Individuals also saw that their time awake was about 15 minutes longer, which was not observed on either the airplane noise or the pink noise-only nights.

“Suppression of N3 (a deeper stage of non-REM sleep) and REM sleep with environmental noise and pink noise, respectively, suggest that both of these decibel ranges can be detrimental to the normal progression of sleep architecture and its restorative function,” said Sarathi Bhattacharyya, MD, pulmonologist, sleep medicine specialist, and medical director of MemorialCare Sleep Disorders Center at Long Beach Medical Center in Long Beach, CA, who was not involved in the study.

The participants also reported that their sleep was lighter, they woke up more frequently, and their overall sleep quality was worse when they were exposed to airplane or pink noise, compared to nights without noise.

The only difference in this was when they used earplugs.

“Earplugs can be appropriate to block out noise in a loud sleep environment, though prolonged use can lead to issues such as earwax impaction,” said Bhattacharyya.

“If there are noise sources under your control or that can be moved, then those should be addressed concurrently to help improve the sleep environment,” he added.

The overall health effects of pink noise and other types of “broadband” sleep aids, such as earplugs, may warrant further study.

The AASM adds that 18% of people use some kind of sound machine or app. Many people use ambient podcasts and white noise YouTube channels while they sleep. Despite the popularity of these types of sleep aids, a 2021 review points out that research on the effects of broadband noise and sleep remains scarce.

“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 in a press release.