White noise machines have earned a devoted following well beyond nurseries, and a growing body of clinical research on adults specifically helps clarify when sound masking genuinely earns its spot on a nightstand.
What a Recent Systematic Review Found
A 2025 systematic review screening nearly 2,000 studies identified seven randomized controlled trials involving 496 hospitalized adults across the United States, India, Iran, China and South Korea, concluding that white noise and similar masking sounds improved sleep efficiency with good tolerability across the reviewed studies. Only 8 participants across all combined studies discontinued use due to discomfort, suggesting the intervention carries genuinely minimal downside for most people.
Why Environmental Noise Matters More Than It Seems
Research measuring hospital noise levels found sound regularly exceeded 45 decibels throughout the day and even reached 51 decibels at 4am, both above World Health Organization recommendations, with noise spikes over 85 decibels occurring multiple times overnight. A separate survey found 78.6% of surveyed patients reported sleep disturbances, with more than half attributing the disruption specifically to environmental noise, a pattern that extends well beyond hospital settings into any home located near traffic, shared walls or street noise.
How White Noise Actually Helps
White noise works by raising the auditory threshold needed to notice sudden environmental sounds, effectively masking sharp, unpredictable noises that would otherwise trigger a brief awakening or arousal. One controlled trial found that exposure to 40 to 50 decibel white noise for one hour before and during early sleep significantly improved sleep quality compared with a control group that received an unchanged, quiet environment.
Where the Evidence Gets More Mixed
A broader meta-analysis spanning infants, adults and older adults found that while white noise generally helps people fall asleep more quickly, the overall quality of evidence remains relatively modest and effects vary considerably between individuals, meaning results that work well for one person may do little for another. This variability is worth setting realistic expectations around rather than treating white noise as a universal fix.
Getting the Most From a Sound Machine
- Keep volume in the 40 to 50 decibel range, roughly the loudness of a quiet conversation, rather than maxing out the device
- Position the machine at a consistent distance from the bed each night, since inconsistent placement changes the effective volume reaching your ears
- Try different sound profiles, since pink noise and other masking sounds beyond pure white noise have shown comparable benefits in various studies
- Give any new sound machine several nights of consistent use before judging its effectiveness, since individual adaptation varies
The takeaway: White noise machines carry genuine, if modest and individually variable, research support for improving sleep by masking disruptive environmental sound, making them a low risk tool worth trying for anyone sleeping in a noisy environment.