New research from the University of Pennsylvania suggests that widely used pink noise machines, marketed as sleep aids, may actually reduce restorative sleep, particularly REM sleep. While many rely on these devices to mask disruptive sounds, the study reveals they can be counterproductive, with earplugs proving a more effective solution for blocking out noise.
The Unexpected Impact on REM Sleep
Researchers monitored 25 healthy adults in a controlled sleep lab, exposing them to various conditions: aircraft noise, pink noise alone, combined noise, and noise while wearing earplugs. The findings were striking. Pink noise significantly reduced REM sleep, the critical stage linked to dreaming, memory consolidation, and emotional processing.
Lead author Mathias Basner, a professor of psychiatry, explained the surprise: “Both the unexpectedly strong reduction in REM sleep from pink noise and the good efficacy of earplugs were somewhat surprising to us.” Participants using pink noise spent more time awake, took longer to fall back asleep, and experienced less time in REM sleep. This matters because REM sleep is increasingly understood as vital for brain health; disruptions may even contribute to neurodegenerative diseases like Parkinson’s.
Why This Matters: Noise and Sleep Science
The popularity of pink noise machines is puzzling given the lack of robust scientific backing. For years, Basner has studied the harmful effects of external noise on sleep. To discover that millions voluntarily introduce another noise source into their bedrooms is a paradox.
Pink noise differs from white noise by reducing higher frequencies, creating a smoother sound often compared to rainfall or waves. However, the study demonstrates that even this “gentler” alternative can interfere with natural sleep cycles.
Caution for Parents: The Risk to Developing Brains
The effects may be especially concerning for children. Infants spend roughly 50% of their sleep in REM, compared to 20% for adults. Suppressing this stage during development could have long-term consequences. Researchers caution against indiscriminate use of broadband noise in nurseries and toddlers’ rooms.
The Bottom Line: Earplugs May Be Better
The study highlights a simple, overlooked solution: earplugs. They proved far more effective at blocking out noise without disrupting sleep quality.
Basner acknowledges the study’s limitations, noting that long-term effects remain unknown. However, the immediate takeaway is clear: if you struggle to sleep, consider earplugs first. And if you use a sound machine, keep the volume low—experts recommend around 50 decibels for children and 60 for adults. The current trend of adding noise to solve noise problems may be doing more harm than good.
