From pink noise to rain sounds and ambient loops, sound machines have become one of the most popular sleep aids around. They promise a buffer against disruptive noises and a smoother transition into rest. You may have used one yourself or recommended it to clients who struggle with sleep.
But new research suggests that these devices — especially ones that play continuous broadband noise like pink noise — may not be the sleep solution we thought they were. In fact, some of them may be interfering with the very sleep stages most important for emotional regulation and mental health.
What the Study Found: Pink Noise and Sleep Stages
A team at the University of Pennsylvania Perelman School of Medicine conducted a controlled sleep lab study with healthy adults. Participants spent several nights under different sound conditions, including pink noise alone, environmental noise (like aircraft sounds), a combination of both, and no added sound at all.
Here’s what they discovered:
• Pink noise reduced REM sleep
Rather than protecting sleep, pink noise played throughout the night led to a significant reduction in rapid eye movement (REM) sleep — the stage associated with dreaming, emotional processing, memory consolidation, and cognitive restoration.
• Combined noise made things worse
When pink noise was used alongside intermittent environmental noise (like aircraft sounds), both REM and deep sleep were reduced, and participants spent more time awake at night.
• Earplugs outperformed sound machines
Simple earplugs were more effective than pink noise at preserving both deep sleep and REM sleep in the presence of environmental noise.
Why REM and Deep Sleep Matter for Mental Health
Sleep is not a monolithic state. It consists of stages that serve very different but equally crucial functions:
• Deep sleep (N3)
This stage helps the body recover and regenerate physically. It’s also associated with immune function and metabolic regulation.
• REM sleep
During REM, the brain processes emotional experiences and consolidates memories. This is a critical stage for emotional balance, learning, and mood regulation.
Even losing 15 to 20 minutes of REM or deep sleep per night can add up over time, especially for people already vulnerable to mood disturbances, anxiety, or burnout.
So Why Do Sound Machines Sometimes Backfire?
The logic behind sound machines is intuitive: mask external noise with a consistent, soothing sound to prevent sudden disturbances. But in practice:
Continuous sound — even “soft” noise — can prevent the brain from smoothly transitioning through its natural sleep architecture.
Broadband noise covers a wide range of frequencies, meaning the brain may not truly “tune it out” the way it would with silence or stable environmental sounds.
The impact appears especially pronounced in REM sleep, which is vital for emotional health and daytime functioning.
This doesn’t mean all sound is bad — it means that constant background sound may not be the best strategy for improving sleep quality.
What Actually Helps Your Sleep and Mental Health
If you or your clients rely on sound machines, here are some evidence-based alternatives and adjustments:
• Start with silence or minimal sound
Reducing environmental noise at the source (closing windows, eliminating street noise) often protects sleep better than overlaying it with sound.
• Use earplugs when needed
For many people, simple earplugs improve both deep sleep and REM sleep without introducing additional stimulation.
• Focus on consistent routines
A stable sleep schedule and pre-bed wind-down reduce the overall effort and stress around sleep.
• Treat sleep as a biological process, not just a comfort habit
Protecting the integrity of REM and deep sleep can support emotional regulation, memory consolidation, and long-term resilience — all of which are linked to mental health.
Sound machines aren’t inherently “bad,” and some people do find relief from them. But the assumption that more sound automatically equates to better sleep isn’t supported by this research. If your goal is restorative sleep — the kind that supports mood, cognition, and emotional balance — simplicity may be more powerful than noise.
Sometimes the most effective “sleep aid” is not adding something new, but removing what interrupts the brain’s natural recovery process.
Citation
University of Pennsylvania School of Medicine. “Sound machines might be making your sleep worse.” ScienceDaily, February 4, 2026. Retrieved from https://www.sciencedaily.com/releases/2026/02/260203030529.htm
