Your Sound Machine Might Be Sabotaging Your Sleep—Here's What New Research Found

Pink noise—the popular sound machine staple that mimics rainfall—may actually be harming your sleep instead of helping it. A new study from the University of Pennsylvania Perelman School of Medicine found that listening to pink noise at bedtime could disrupt REM sleep (the stage where dreams occur) and reduce overall sleep recovery, even though many parents and adults use sound machines with good intentions. The research suggests that earplugs may be a more effective solution for blocking disruptive environmental noise like traffic or aircraft sounds.

What Does Pink Noise Actually Do to Your Sleep?

Researchers at Penn Medicine conducted an eight-night sleep lab study with 25 healthy adults between ages 21 and 41 to measure how different types of noise affected their rest. The participants were exposed to various sound conditions, including aircraft noise alone, pink noise alone, a combination of both, and aircraft noise with earplugs. Each morning, they completed tests and surveys to assess sleep quality, alertness, and overall health effects.

The findings were striking. Pink noise at 50 decibels—which sounds similar to moderate rainfall—was associated with almost a 19-minute decrease in REM sleep compared to nights with no noise. When aircraft noise and pink noise were combined, participants experienced significantly shorter periods of both REM and deep sleep, plus they spent about 15 minutes longer awake during the night. Participants also reported that their sleep felt "lighter," the overall quality was worse, and they woke up more frequently when exposed to these noise conditions.

Why Does This Matter for Your Brain?

REM sleep isn't just about dreaming—it's critical for essential brain functions. "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," explained Dr. Mathias Basner, professor of sleep and chronobiology in psychiatry at Penn Medicine. REM sleep is important for memory consolidation, emotional regulation, and brain development, making it particularly concerning when sound machines reduce this stage.

Deep sleep and REM sleep work together to ensure you wake up feeling restored. Deep sleep handles physical restoration, memory consolidation, and clearing toxins from the brain, while REM sleep manages emotional processing and learning. When pink noise disrupts REM sleep, you're essentially sacrificing one of these critical restorative processes.

What About Other Types of Noise Machines?

Not all sound machines work the same way. Sleep experts recognize important differences between popular noise types:

• White Noise: Produces equal energy across all frequencies and sounds like harsh radio static, potentially creating a different impact on sleep than pink noise.
• Brown Noise: Emphasizes lower frequencies, resulting in a deep, bass-heavy rumble similar to distant thunder or a heavy waterfall.
• Pink Noise: Has more energy at lower frequencies than white noise but not as deep as brown noise, creating a "perceptually balanced" sound like steady rainfall or wind.

"While pink noise might mask external disruptions, it introduces a constant stimulus that the brain still has to process," said Dr. William Lu, a San Francisco sleep expert and medical director of Dreem Health. "The most concerning finding is that we may be unknowingly sacrificing segments of our REM sleep."

When Might Pink Noise Actually Help?

The research isn't entirely negative about pink noise. Dr. Basner noted that pink noise did have some positive effects in specific situations. "If low amounts of deep sleep and sleep fragmentations are someone's main sleep issues, pink noise could be overall beneficial for them," he explained. This means that for people whose primary sleep problem is fragmented deep sleep caused by intermittent environmental noise, pink noise might provide a net benefit by masking those disruptions, even if it slightly reduces REM sleep.

However, for most people without specific sleep fragmentation issues, the research suggests a different approach is better.

What's the Better Alternative?

The study found that earplugs were significantly more effective at blocking out traffic noise during sleep while preserving sleep quality. When participants used earplugs during aircraft noise exposure, they prevented the decline in deep sleep "to a large extent" compared to nights without protection. Earplugs improved sleep quality among study participants without introducing the constant auditory stimulus that pink noise creates.

Based on this research, sleep experts are reconsidering sound machines as a first-line sleep solution. The key takeaway is that while the intention behind using sound machines—especially for infants and toddlers—comes from a good place, the actual impact on sleep architecture may be counterproductive for most people. If you're struggling with noise disruptions, earplugs or addressing the noise source directly may be more effective strategies than adding another sound to the mix.