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

For years, I’ve been a loyal sleep-sounds person. Rainstorms, ocean waves, the steady hum of pink noise, I’ve rotated through all of it. For probably a decade, I rarely fell asleep without some kind of background sound playing. It felt soothing, like a cue to my brain that it was time to power down.

And I’m clearly not alone. Millions of people rely on white or pink noise apps, fans, or sound machines every night. But a new controlled sleep-lab study suggests the story may be more complicated.

To really test whether sound machines help or hurt, researchers brought 25 healthy young adults into a sleep lab for seven separate nights. Each night came with a different sound setup.

Some nights included intermittent environmental noise, such as traffic passing by, an alarm going off, or a crying baby. Other nights, participants heard pink noise on its own. Some nights combined environmental noise with pink noise. Others paired environmental noise with simple foam earplugs. And one night? Quiet, as a control.

Throughout it all, researchers closely monitored sleep stages, nighttime awakenings, and overall sleep architecture using full polysomnography. In the morning, participants took cognitive tests and filled out surveys about their mood and alertness.

First, the predictable part. Intermittent environmental noise reduced deep sleep (also known as slow-wave or N3 sleep). That lines up with decades of research showing that sudden sounds fragment sleep and make it harder for the brain to stay in its most restorative state.

But here’s where it gets interesting.

Pink noise, commonly marketed as a sleep aid, didn’t meaningfully disrupt deep sleep. Instead, it reduced REM sleep. On average, participants lost about 19 minutes of REM sleep on pink noise nights compared to quiet control nights.

When pink noise was layered on top of intermittent environmental noise, sleep structure worsened further. Total sleep time dropped, sleep efficiency declined, and awakenings increased.

So while pink noise did slightly reduce some noise-related fragmentation, it also introduced its own shift in sleep architecture. In other words, it didn’t fully cancel out the problem, and in some cases, it added a new variable.

Interestingly, participants didn’t always feel dramatically worse after pink noise alone. But objectively, their sleep stages had changed.

In contrast, earplugs performed surprisingly well.

Simple foam earplugs mitigated nearly all of the negative effects of environmental noise on sleep, except at the very highest sound levels tested. Deep sleep was largely restored. REM sleep remained stable.

Participants also generally found the earplugs comfortable and reported sleeping well while wearing them.

Morning cognitive testing didn’t reveal dramatic next-day differences between conditions. But it’s important to note this was a short-term study, and even on noisier nights, participants were still averaging just over seven hours of sleep. Over longer stretches of time, small changes in sleep architecture could add up in more meaningful ways.

Not necessarily. Context matters.

Personally, this research made me reconsider my own habit. I’ve started experimenting with quieter nights and, occasionally, earplugs instead of looping rain sounds.

Sleep is incredibly dynamic. The brain doesn’t just “turn off” at night; it cycles through carefully orchestrated stages that each serve a purpose. When we intervene, even with something as seemingly gentle as pink noise, it’s worth understanding what might shift under the surface.