Do white, brown and pink noises aid with sleep and concentration?
Listening to coloured noise has often been touted as a sleep aid, to increase productivity and help people relax. We asked an expert to explain how it really affects our brain.
White noise, which is defined as “a heterogeneous mixture of sound waves extending over a wide frequency range”, is a well-known tool to facilitate concentration in offices or help with sleep. Now “brown noise” is popping up on the social media app TikTok, praised by users as a way to focus, especially and allegedly for people suffering from attention deficit disorder (ADHD).
In fact, the hashtag #brownnoise has racked up an impressive 71.1 million views as of August 2022. But is it as effective as people claim?
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White noise, brown noise and pink noise: What’s the difference?
White noise is made up of sound that includes all frequencies that are audible to the human ear, which ranges between 20 hertz and 20,000 hertz. When these frequencies are played at an equal intensity or amplitude, measured in decibels, it produces those “background” sounds; such as TV or radio static, an air conditioner or a whirring fan.
“White noise is a combination of random sounds across all the frequencies we can hear which our brains interpret as static,” explains Dr Leigh van den Heuvel, a psychiatrist and lecturer in the Department of Psychiatry at Stellenbosch University.
Pink noise is similar to white noise, but instead of the higher frequencies it produces more bass and mid-range tones. While white noise “plays” all frequencies equally, pink noise excludes those higher sounds, making it soothing and reminiscent of water falling, waves breaking on the shore or rain on a roof. Listen closely and you will hear pink noise in nature; in the rustle of leaves in the trees, in the wind and in our own heartbeats.
Brown noise goes even deeper, emphasising those bass notes even more and almost completely excluding the high notes. This makes brown noise sound like heavy rain, rumbling thunder or the engines of an aeroplane.
“Pink and brown noise are variations of white noise; in pink noise the volume of high frequency sounds is dampened, producing an effect of a deeper static noise. In brown noise this effect is further enhanced, producing an even lower-pitched sound,” Van den Heuvel says.
(Interestingly, brown noise is not actually named for the colour, like white and pink noise are. Instead, it is named for Scottish scientist Robert Brown, who created a mathematical formula to generate electric sound, which became known as Brown noise.)
What does coloured noise do?
Noise is all around us all the time, and our brains learn to tune things out and tune in to other things.
“When it comes to noise, our attention is directed towards changes in noise, such as a car hooting, a dog barking, or a sudden shrill voice,” says Van den Heuvel.
What coloured noise does is help the brain to tune out those changes and to mask the fluctuations, as the continuous sound makes other noise less apparent and less likely to distract or draw attention, she continues. This may particularly help people who work in loud, busy spaces or who are distracted easily.
“Revolutionised how I study”
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Does listening to coloured noise help with sleep or concentration?
Listening to coloured noise has often been touted as a sleep aid, to increase productivity and help people relax. However, while there is more literature on the effects of white noise, brown noise and pink noise are still being researched, and the jury is still out. Here is what we know so far.
“Noise can be very disruptive, especially for sleep or when we need to concentrate. Coloured noise can potentially assist in lessening the disruptions caused by noise. It is also postulated to have a relaxing effect,” says Van den Heuvel.
“There is increased interest in the potential utility of coloured noise to influence or treat a number of conditions. One of the main areas of interest is to improve sleep or treat insomnia.”
Recently, however, two studies on the effect of coloured noise on sleep found that the evidence that coloured noise improved sleep was inconclusive. A systematic review on the topic in the Journal of Clinical Sleep Medicine found mixed results, and even stated that “there was no strong evidence to support use of auditory stimulation” to improve sleep. The study, published in 2022, found results on both ends of the spectrum, where disrupted sleep from white noise and improved sleep were recorded. The researchers say “the quality of evidence for continuous noise improving sleep was very low, which contradicts its widespread use”. In short, there is not enough evidence to say coloured noise absolutely improves sleep.
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When it comes to attention-deficit/hyperactivity disorder (ADHD), again, the evidence is inconclusive.
Van den Heuvel explains that core to the symptoms of ADHD is a person’s difficulty with paying attention, which makes them more vulnerable to the interruptions caused by noise.
“Some studies suggest that there is promise for coloured noise in improving performance on certain tasks in children with ADHD, but not others. Coloured noise thus shows potential as an add-on intervention in ADHD, but the research evidence remains limited and uncertain.”
“Other areas being investigated include improving cognitive performance in various populations, in correcting balance and preventing falls in the elderly, enhancing efficiency at work, and reducing pain perception during procedures and investigating brain function of, for instance, people with psychotic illnesses,” Van den Heuvel says.
“Although coloured noise shows promise in managing a number of conditions, for most of these the evidence base is insufficient to recommend it.”
Coloured noise: too good to be true?
Van den Heuvel does warn of possible negative effects of listening to white, pink or brown noise, noting that “coloured noise can potentially disrupt cognitive performance and sleep, and cause hearing damage if it is too loud”.
“Furthermore, authors have noted that though coloured noise can seemingly improve tinnitus in the short term, in the long term it can possibly lead to maladaptive rewiring of the brain. This rewiring doesn’t treat the underlying problem but may actually contribute to worsening it and could potentially have negative effects on brain function, such as impairing cognition.”
The risks aren’t too high, she assures, but they are worth being aware of. And if coloured noise helps you sleep or concentrate without adverse effects, then that’s a win – it could change the way you work or study for good. “For individuals who would like to try coloured noise for various indications, the risk of doing so is likely not very high for most, but if the coloured noise does not help or produces side-effects, it is advisable to stop using it. Always make sure the volume of the coloured noise is within safe limits to prevent hearing loss.” DM/ML
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