Is White Noise Harmful or Helpful for Sleep?
Does white noise actually improve sleep? And how does it impact hearing and brain development?
Source: Pexels/Karolina Grabowska
White noise during sleep has somehow become a very controversial topic. On one hand, many parents are advised that “white noise” is essential for helping their children to sleep and are compelled to buy expensive “white noise machines” for their babies and toddlers. Yet, on the other hand, there are claims on social media and blogs that white noise may hurt children’s hearing or even negatively impact their brain development. There are also claims that white noise can become a “sleep crutch” meaning once you start using it your child will become dependent on white noise to fall asleep.
So does research find that white noise helps children to fall and stay asleep? And are there any harmful effects of blasting white noise during all of your child’s sleeping hours? You can read the full newsletter or listen to the newsletter by clicking the button below!
What Is White Noise?
White noise is often recommended to help children sleep and/or block out sounds that might wake a child (traffic noise, barking dogs, etc). An expensive white noise machine seems to be on every baby registry list and there are countless white noise apps on the market which claim to improve sleep.
White noise is the term commonly used to describe any continuous sound emitted from white noise machines, fans, static, or even natural sounds (like rain or waves in the ocean). Yet, according to the scientific definition, “white noise” is actually a very particular sound— one that contains all sound frequencies that the human ear can hear played simultaneously at equal intensities.
What we think of as “white noise” may actually be “pink noise,” “brown noise,” or some other combination of sound frequencies and intensities. “Pink noise” is similar to white noise in that it includes all sound frequencies but it involves the lower frequencies being played a little bit louder than the higher frequencies. “Brown noise” contains all frequencies but plays the lower frequencies louder and the higher frequencies quieter than white noise. See here to listen to the differences between white noise, pink noise, and brown noise.
Does White Noise Actually Improve Sleep?
A recent systematic review concluded that there is very weak evidence supporting the use of white noise in improving sleep despite its widespread use. Researchers have found that white noise tends to reduce the time it takes to fall asleep (referred to as sleep onset latency) and night awakenings (referred to as fragmented sleep) but most results were not significant (likely due to small sample sizes).
Several small studies have found that white noise may help some babies to fall asleep. One randomized controlled trial (translation: the “gold standard” of research studies) involving only 40 newborns found that 80% of the infants fell asleep in the white noise group while only 25% did in the control group. Another study in adults found that white noise has a positive impact on falling asleep but does not have any significant impact on total sleep time or sleep quality throughout the night. However, one small study in adults found that white noise actually reduced sleep quality.
White noise may also help to block out other noises in the environment that might disturb sleep. One study found less sleep fragmentation when healthy adults listened to white noise while a recording of noises from the intensive care unit were played, suggesting that white noise may help to block out normal hospital sounds. Another study examined people living in New York City who complained about too much environmental noise and they found that using a white noise machine reduced the time it took them to fall asleep and increased the time they slept before their first awakening.
White noise may also act as “stimulus control” meaning that it serves as a cue that it is time to sleep. If you consistently play white noise when your child is about to fall asleep or sleeping, your child will begin to associate it with sleep and ultimately it can signal to their body that it is time to fall asleep. Although there is no research specifically on white noise as a sleep cue, there is some evidence that other stimulus control techniques may improve sleep.
White noise may also be soothing for infants. Research finds that white noise may reduce pain during vaccination in premature infants. Another study found that white noise may be more effective than lullabies at reducing infants’ heart rates and breathing rates during painful procedures. Finally, a study involving 40 one-month-old infants found that white noise may help to soothe babies with colic better than the control condition, which was swinging the babies.
Is White Noise Harmful for Hearing?
According to standards for hospital nurseries, noise levels should not exceed 50 decibels for infants. The National Institute for Occupational Safety and Health recommends that noise not exceed 85 decibels for adults. Therefore to be safe, white noise should probably not exceed 50 decibels for infants and children and should not exceed 85 decibels for adults.
One study assessed 14 white noise machines on the market for infants. They found that all of the devices exceeded noise level recommendations when placed less than three feet from the infant’s ears at maximum volume. However, when placed across the room, most white noise machines did not exceed noise recommendations. Another study found that no popular white noise machines or apps were too loud at any distance (even inside the crib) when used at the minimum volume setting.
Does White Noise Impact Brain Development?
Research with animals suggests that prolonged exposure to white noise may impact brain development. However, this study involved 24 hours of continuous exposure to white noise and no other sounds. More importantly, there is no evidence in humans that prolonged exposure to white noise has a negative impact.
A small study of infants in the NICU found differences in brain activity for infants when exposed to white noise versus music for one hour, yet they found no differences in brain activity between music and the typical sounds of the NICU. There is also evidence that infants have a different brain response than adults to white noise. Yet, it remains unclear what these brain activation differences really mean in terms of future brain development. Until we have further research, brain activation differences are simply differences and we have no way of knowing whether they might have a positive, negative, or negligible impact on future brain development.
There is also some evidence that white noise has a positive impact on brain functioning, at least in adults and children. In adults, white noise improves memory and learning. Research also finds that white noise may also improve memory performance in children with ADHD.
What about Brown Noise, Pink Noise, Lullabies, Etc.?
As mentioned above, many white noise machines and apps actually do not emit white noise but pink noise, brown noise, and other combinations of frequencies and intensities of sounds. Some white noise machines will also play soothing music or natural sounds (raindrops, waves, etc). There is very little research differentiating these different types of noises.
Research in adults found that pink noise during sleep may change brain activity in a way that results in less disrupted sleep and enhanced memory consolidation. For this reason, pink noise has been proposed as a potential treatment for individuals with sleep problems or older adults with memory difficulties. Pink noise has also been found to improve executive function when used during a difficult task. However, there are very few studies on this topic and more research is definitely needed before concluding that pink noise is beneficial.
Unfortunately, there is also very limited research on brown noise, red noise, violet noise or other noises which vary based on the intensities of different sound frequencies. Yet, despite the lack of research on this topic, brown noise is very hot on TikTok (with 115 million views for the hashtag #brownnoise with many people claiming it quiets their brain).
What about listening to music or lullabies? A randomized controlled trial in premature infants found that lullabies improve sleep quality and lower heart rates in infants. Even unfamiliar lullabies seem to have a calming impact on babies. Research also finds that music (click here to hear what they listened to in this study) improves sleep quality in adults. Another study in fifth graders found that listening to music at bedtime was associated with better sleep quality.
Overall Translation: How Do I Apply This Research?
Research provides some limited evidence that white noise may help sleep. However, there is no evidence that white noise is necessary to help babies or children to sleep or that it will solve all sleeping problems. There is also no evidence that white noise causes any harm when played at a reasonable volume. Pink noise or music may also help with sleep.
Overall, the research suggests the following:
Don’t feel like you need to use white noise if you don’t want to or don’t think it is necessary. Research does not clearly show that children need white noise to fall asleep or stay asleep so only use it if you find it helps your child or blocks out other noises that could potentially disrupt sleep.
You should also not worry about any long-term negative impacts of white noise (as long as the volume is kept at a safe level). We have no evidence that white noise causes any harm to infants or children.
If you choose to use white noise, use an app (such as NIOSH Sound Level Meter App) to make sure that the noise is not too loud. Place your phone in the crib (or wherever your baby sleeps) when your baby is not sleeping and find the right volume level that is less than 50 decibels. The American Academy of Pediatrics also advises that the white noise machine is at least 6.5 feet away from the crib.
If you don’t like the idea of white noise playing all night long, play it only when your child falls asleep or have the volume gradually decrease over the course of the night (you can use a “smart” white noise machine such as the Hatch nightlight).
Instead of white noise, try pink noise or music/lullabies which research also suggests may help with sleep.
All Parenting Translator newsletters are reviewed by experts in the topic to make sure that they are as helpful and as accurate for parents as possible. Today’s newsletter was reviewed by Shelby Harris, PsyD, DBSM. Dr. Shelby Harris is a clinical psychologist and sleep specialist in private practice in NY. She is board certified in Behavioral Sleep Medicine and treats a wide variety of sleep, anxiety and depression issues using evidence-based, non-medication treatments. Her self-help book, The Women’s Guide to Overcoming Insomnia was published in 2019 by W.W. Norton Books. Dr. Harris holds an academic appointment as Clinical Associate Professor at the Einstein College of Medicine in Neurology and Psychiatry. Before going into private practice, she was the longstanding director of the Behavioral Sleep Medicine Program at Montefiore Medical Center in NYC. Dr. Harris has been an invited columnist for the New York Times “Consults Blog,” and is frequently in the media, including the New Yorker, Washington Post, Today Show, and Good Morning America. Dr. Harris can be found on Instagram at @SleepDocShelby where she provides evidence-based information about sleep wellness and sleep disorders.
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Welcome to the Parenting Translator newsletter! I am Dr. Cara Goodwin, a licensed psychologist with a PhD in child psychology and mother to three children (currently an almost-2-year-old, 4-year-old, and 6-year-old). I specialize in taking all of the research that is out there related to parenting and child development and turning it into information that is accurate, relevant, and useful for parents! I recently turned these efforts into a non-profit organization since I believe that all parents deserve access to unbiased and free information. This means that I am only here to help YOU as a parent so please send along any feedback, topic suggestions, or questions that you have! You can also find me on Instagram @parentingtranslator, on TikTok @parentingtranslator, and my website (www.parentingtranslator.com).
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Thank you for sharing this research as I know it is a question being brought to child care classrooms and homes across the country. The recommendations you share make it easy for parents and providers to put the information to use immediately.