White Noise as a Sleep Aid – Summary of the Science Behind Our Concerns

Point 1: The young brain needs, expects, and is focused on auditory variation in the environment to help it build language networks.

Critical periods are windows of time when the brain is especially receptive to outside “experiences” or stimuli that help shape its cognitive structures – what neuroscientists call plasticity. The entire first year of life is a critical period for language when the brain builds its acoustic map, the collection of neuronal connections that process the basic units or phonemes of a child’s native language(s); in English, for instance, the p and b sounds in pad and bad are phonemes.

These phonemes differ from each other by tiny – in the 10s of milliseconds – transitions in sound, so the infant brain must become adept at recognizing and processing those differences quickly and very accurately to acquire language. The very specific, tightly connected acoustic map helps the brain to do that, allowing the child to go on and decode incoming language streams to recognize patterns that makeup words and then attach meanings to those words.

Even past the first year, after the acoustic map has formed, these language networks continue to develop and become more sophisticated and efficient. In some circumstances, connections and networks expand, for instance, to accommodate language development moving from phonetic learning to include more complicated information such as syntax and the association of words with other experiences, such as touch (the apple felt smooth) and sight (the apple was red). In other cases, “pruning” occurs, eliminating connections and neurons that have become redundant or unnecessary (such as those for processing phonemes of another language that are not native to the child).

It all begins, however, with the acoustic map. To form that map, from birth (and even before), the infant brain focuses on sound variations in the environment, salient acoustic cues that are differences in intensity, duration, or pitch, for instance, that are properties of speech sounds and will help it, over time identify the phonemes of its native language, and ultimately build the acoustic maps and other language networks it needs to be an efficient language processor.


Point 2: Even during sleep, the infant brain is listening for that variation.

Sleep is an incredibly important time for brain development, particularly for infants, who may spend 16 to 20 hours in sleep. Indeed, 90% of brain plasticity (the changes in brain structure caused by its responses to external stimuli) occurs during sleep in infants as well as adults, given that some parts of the brain remain active to build, prune, and tune neural networks. In the case of early language networks, the particular brain areas responsible for processing speech and speech-like sounds are actively organizing and are listening for sound transitions in the environment that will help them do just that.


Point 3: White noise has no variation, so it does not provide the auditory cues that support the development of language networks.

White noise is all frequencies at the same intensity, so it lacks variation. Additionally, since it is often used by parents to mask other sounds, it also prevents variation from coming in from other sources. That means that for the length of time a child is exposed to white noise, they are not receiving the acoustic stimuli the brain relies on for early language development.


Point 4: Animal studies show that exposure to white noise impedes or delays development.

Research using rat pups definitively shows that exposure to continuous white noise delayed or impeded auditory tuning and the development of the auditory cortex, the part of the brain responsible for processing sound, including phonemes in human babies, because the brain was not receiving the variable acoustic stimulation that supports that tuning and development. The infant rat is an excellent model for human cortical development, so rats are often used for studies where the use of humans would be impractical or unethical (as would be the case for evaluating the harm of white noise to language development in infants). In the case of these white noise studies, researchers pointed specifically to the very negative implications of white noise for human language development based on the results they saw in rats.


Point 5:  Studies of human infants in suboptimal sound environments that lack or mask relevant sound variation also demonstrate disrupted acoustic cortex mapping.   

Studies on infants in Neonatal Intensive Care Units (NICU) environments that lack or mask auditory cues (both in open rooms where the high noise levels obscured variation and in private rooms where the lack of sound also deprived infants of needed variation) and in other suboptimal auditory environments (orphanages for instance) showed language development delays in affected children that were consistent with the acoustic cortex delays which resulted in animals exposed to white noise.


Point 6: The evidence that white noise supports sleep is weak.

Systematic reviews failed to identify any meaningful sleep benefit from white noise. Given those results, some researchers suggest that the positive effects popularly attributed to white noise by parents might simply reflect using white noise as part of a sleep routine since no intrinsic benefits could be attributed to white noise itself.  In other words, it’s the sleep routine that’s helping the child, not the white noise per se.



During sleep, a high-quality acoustic environment that includes sound variation, especially the salient acoustic cues that help identify language sounds (in combination with extensive exposure to human speech during awake times), provides optimal support for early language development. In contrast, the use of white noise during sleep presents a real risk to that development, with the risk heightened for young children with a family history of language-learning impairment, ADHD, or some types of autism spectrum disorder – all of which are associated with higher rates of language issues.

Additionally, the popular belief that white noise supports sleep better than sleep sounds, such as music or nature sounds, or other varying soundtracks that do not pose a risk to language development, is not well-grounded in the research.

As a result, it makes good sense to switch to a supportive sound environment, whether it is simply the natural nighttime environment or one created by a sound machine or app providing a soundtrack with acoustic variation that doesn’t carry the risks that white noise does. At the very least, parents and caregivers should be provided accurate information about what developmental neuroscience tells us about the crucial need for environmental variation during sleep so they can make an informed decision on behalf of the children in their care.