Among emerging trends to improve sleep is the idea to generate neutral noise as a way to drown out distracting noises or fill gaps in the silence. For some, too much silence can be just as disturbing as car alarms or traffic. Due to the rise in both technology and sleep issues, "white noise" sound machines, apps and streaming playlists have become a necessity for many to get some good shuteye.
According to a recent market analysis, the global white noise machine market size is expected to reach $1.9 billion by 2028. A white noise machine is usually a must-have item on baby registries, as it's recommended by many infant sleep consultants to help babies sleep. Some articles proclaim white noise will give you the "best sleep ever." However, the opposite may be true.
While it's true that white noise can mask background noise — which logically seems like an advantage for restful snoozing — there is a rise in research and scientists showing that white noise could potentially be negatively affecting human brain development, especially in infancy.
White noise contains all frequencies across the spectrum of audible sound to the human ear, just like how white light contains all colors in the color spectrum. Also known as "broadband sound," white noise plays all audible frequencies at the same intensity, which is measured in decibels. White noise sounds like a "shh" sound in the form of radio static or the hum of an air conditioner. Some of the most viewed videos on YouTube are hours and hours of nothing but gauzy, soft sound.
Hundreds of millions of people have tuned into these vanilla vibrations, but while it seems harmless, neuroscientist April Benasich says early in life, it could be keeping the infant brain from doing its job to be able to decipher between sounds, which ultimately helps them develop language skills later in life.
"The infant brain is exquisitely sensitive to acoustic cues in the environment, these tiny changes in sound that occur in the 10s of milliseconds. That helps it to focus on phonemes, which is the smallest unit of language, and promote the creation of the neuronal connections that helped to process those phonemes automatically," Benasich told Salon. "This automatic processing is what allows a child to decode the rapid sounds of the incoming language stream, so they can identify phonemes, words made from phonemes, and then associate actions, objects and sensations with those words as they get older."
Benasich said exposure to these relevant acoustic cues is "essential" to language development, especially during sleep, which is a very active period of brain development for infants.
"White noise, there's no variation there, and so you're masking the sounds that the developing brain needs to listen to during that time period early on," she said. "And that's why white noise is definitely not what you should be using for your baby."
There are other types of noise based on the frequencies that are emphasized. For example, pink noise has reduced higher frequencies, which can resemble noises like rainfall or a waterfall. Brown noise focuses on low-frequency sound that creates wind-like sounds. However, Benasich said the "color" isn't the point — they're all happening at the same intensity, hence masking out variations that the infant brain craves to decode sounds.
However, it's true that there has been research touting the so-called benefits of white noise. In one study published in the journal Sleep Medicine, 10 people living in New York City found that white noise helped mask environmental noise. Another study published in the journal Frontiers in Neurology in 2017 found that white noise decreased the time it took for 18 people between turning their lights and falling into stage 2 sleep by 38 percent. Aside from sleep, some research has suggested that white noise could be a "therapeutic option" for children with ADHD by improving focus on tasks. In a small study from University of Southern California researchers, for people who don't have ADHD, there still could be cognitive benefits from quiet levels of white noise.
In a systematic review Mathias Basner, a professor of psychiatry at the University of Pennsylvania School of Medicine, identified 38 studies that have investigated noise as a sleep aid. While there was evidence that white noise reduced the amount of time people fell asleep, Basner and his co-authors concluded that the quality of these studies was low and that there is no evidence to suggest that there are actually benefits to using white noise. His results were published in Sleep Medicine Reviews in 2020.
"There were like one or two studies that used the gold standard for measuring sleep — polysomnography — and one study found that actually introducing the white noise in the bedroom was disturbing sleep more," Basner told Salon. "There's really not much out there, so there's no way to conclude that it's either good or bad for your sleep. We really just need more research and also more rigorous research."
Basner said he agrees there are potential negative effects of using white noise while you sleep for a number of reasons. First, he said that if a sound is being played back constantly it could negatively affect sleep. Then there's the idea that the brain is recuperating while we sleep.
"The idea is that the auditory system also needs to recuperate and the best time to do that is during the night because sound levels are typically lower," Basner said. "So, introducing a noise source in the bedroom basically means that the auditory system is constantly processing those noise events or those sounds."
He added that it could have consequences "noise-induced hearing loss in the long run," too. In addition to being dangerous: what if it masks the noise of a fire alarm or a child crying?
As for infants and toddlers, Basner said we need more data, especially in regards to long-term exposure. Fortunately, he and his colleagues are working on a study to try and answer some of these questions. In the meantime, he doesn't think it's a good idea to do white noise or any color of noise.
"They're all broadband noise," Basner said. "in my field, sleep research, we wouldn't be able to say whether one is better, better or worse than the other because there's literally nothing out there."
