Could Sound Machines Hurt Your Sleep? A New Study Raises Questions

Reported by MindBodyGreen.

The sleep-sounds habit feels almost universal at this point — rain apps, white noise machines, the fan on high, whatever it takes to drown out the world. Millions of people swear by it. But a new controlled sleep-lab study is complicating the story, and the findings are worth sitting with, according to MindBodyGreen.

Researchers brought 25 healthy adults into a sleep lab for seven separate nights, each night featuring a different audio condition: environmental noise alone (think traffic, alarms, a crying baby), pink noise alone, the two combined, foam earplugs paired with environmental noise, or silence as a control. Sleep architecture was tracked via full polysomnography, and participants completed cognitive assessments and mood surveys each morning. The results confirmed what we already know — intermittent environmental noise chips away at deep, slow-wave sleep. But the pink noise finding? That's the plot twist.

Pink Noise Has a REM Problem

Pink noise didn't significantly disrupt deep sleep the way sudden environmental sounds did. Instead, it quietly eroded REM — participants lost an average of 19 minutes of REM sleep on pink noise nights compared to silent control nights. That's not a trivial number. REM sleep drives memory consolidation, emotional regulation, brain plasticity, and neurodevelopment. When pink noise was layered on top of environmental noise, things got worse: total sleep time dropped, efficiency declined, and nighttime awakenings increased. Subjectively, participants didn't always feel worse. But their sleep stages told a different story.

Foam earplugs, on the other hand, quietly outperformed. They preserved both deep sleep and REM in nearly all noise conditions tested, except at the highest sound levels. Participants found them comfortable and reported sleeping well. The morning cognitive tests didn't show dramatic differences between conditions — but this was a short-term study, and researchers note that even subtle architectural shifts in sleep can compound meaningfully over time. There's also a specific flag for parents: given REM's outsized role in early brain development, the researchers suggest caution around nightly sound machines for infants and toddlers until longer-term data exists.

None of this means you need to immediately retire your sound machine. If you live on a noisy block or share walls with unpredictable neighbors, some masking is better than lying there stewing. But if your goal is actually protecting your sleep — not just making it feel more tolerable — physical sound reduction appears to be the stronger strategy. Start with earplugs, better window insulation, or addressing the noise source directly. If you do use sound, keep the volume low. The research is a useful reminder that the brain doesn't just switch off at night; it moves through carefully sequenced stages that all serve a purpose, and what feels soothing on the surface can still create shifts underneath.

Masking noise and eliminating its impact on your sleep are two very different things — and your REM cycle knows the difference.

Read the original at MindBodyGreen.