White noise is also noise. Can it really help you sleep? Many people ignore this premise.

Original by Yu Zhouwei Popular Science China

Have you ever had the following experience:

It is very easy to fall asleep when riding on a train, especially when you hear the clacking sound of the rails.

It is easy to fall asleep with the sound of a black and white TV with no program signal and dots all over the screen;

In the hot summer, spread a cool mat on the ground, listen to the cicadas chirping in the trees outside, and the regular "whoosh" sound of the fan beside you, and you can fall into a nap very "silky"...

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Here is a question: Isn’t it said that sleep requires quietness? Why don’t these “noises” affect sleep, and even make people feel that they sleep better?

In fact, this involves the study of a special kind of noise - white noise.

Can white noise improve sleep?

The name white noise is taken from light. All light visible to humans mixed together is white light. So white noise refers to a kind of noise that contains all the frequencies on the sound spectrum that can be heard by the human ear.

Based on this characteristic, white noise is also called "broadband noise". In the streets and on the Internet, people often compare white noise to the sound of a radio or TV that is full of "dots" when it cannot receive a radio station.

Image source [1] Official website of the American Sleep Foundation (www.sleepfoundation.org)

Can white noise really improve sleep? It depends on the time. You know, after all, white noise is also a kind of "noise". From the perspective of a conducive sleep environment, keeping quiet is still the first choice. The main reason why some people think that white noise is better may be because this regular sound can partially "cover" the "uncertain" noise in the environment.

In the field of white noise and sleep, the earliest searchable randomized controlled trial dates back to 1990. The researchers studied two groups of 20 newborns, aged between 2 and 7 days old. 16 babies (80%) fell asleep within 5 minutes after hearing white noise, while only 5 (25%) in the control group fell asleep spontaneously. The researchers believe that white noise may help mothers soothe babies who are more "difficult to soothe". Of course, the premise is that the child has been full - white noise does not "mask" internal physiological needs.

Interestingly, there was a lack of relevant randomized controlled trials for quite a long time after that. According to the search results in Pubmed, the second clinical study on white noise was published in 2014, 24 years after the last one.

In 2021, researchers at Weill Cornell Medical College conducted a small sample experiment (10 participants, 5 of whom were women) to see if white noise could improve the sleep of people who have trouble sleeping due to environmental noise. The results showed that white noise can improve the sleep of people who have trouble sleeping due to high levels of environmental noise, including sleep latency and wakefulness at night, based on subjective and objective measurements. This means that when environmental noise affects sleep, you can try using white noise devices to "mask" some of the interference.

Can I use a white noise app?

What should I pay attention to when using it?

According to the World Health Organization, nearly 25% of people have their sleep disturbed by environmental noise, and this problem is particularly evident in urban areas. Therefore, for people whose surrounding environment is not very good, you can try playing white noise equipment to play a partial buffering role.

At present, there are many white noise apps in smartphones, and there are also some small boxes that play white noise on the market. You can try them. Here are a few tips during use:

1. Don't play it too loud. Again, white noise is also noise. The purpose of playing it is to cover up the "harsh, irregular" noise from the outside world. If the sound is too loud, it will become a new noise source. What is the specific volume? There is no official data for reference at present. You can try and feel it based on your life experience, for example, refer to the volume of the "whirring" of the fan or the volume of the radio without radio before.

2. With white noise, do some other "bedtime rituals" that can relax you, such as reading, tidying up the bedroom, etc. The purpose of doing this is to further allow you to focus on the specific things you like, rather than "just thinking about sleeping."

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3. You can set a timer for the white noise to play, for example, it will automatically turn off after playing for 1 hour. The reason is the same as before, white noise itself is also a kind of noise, and its main purpose is to "cover up" environmental noise, not to say that it has any magical effect.

If your environment is okay, or although there are some noises, you would not have found them bothersome in the past, but now you feel that they particularly interfere with your sleep, can you use white noise at this time?

My answer is: you can give it a try. If you feel that this kind of empty sound brings you a sense of stability and comfort, then it can improve your sleep to some extent. If you feel that it doesn't work after a few days, don't be obsessed with it. After all, there are many reasons behind poor sleep and many comorbidities. At this time, you can consider seeing a specialist to evaluate the potential causes or triggers together.

References

[1]https://www.sleepfoundation.org/noise-and-sleep/white-noise ↑

[2]Spencer JA, Moran DJ, Lee A, Talbert D. White noise and sleep induction. Arch Dis Child. 1990 Jan;65(1):135-7. doi: 10.1136/adc.65.1.135. PMID: 2405784; PMCID: PMC1792397. ↑

[3]Ebben MR, Yan P, Krieger AC. The effects of white noise on sleep and duration in individuals living in a high noise environment in New York City. Sleep Med. 2021 Jul;83:256-259. doi: 10.1016/j.sleep.2021.03.031. Epub 2021 Apr 6. PMID: 34049045. ↑

[4]Ebben MR, Yan P, Krieger AC. The effects of white noise on sleep and duration in individuals living in a high noise environment in New York City. Sleep Med. 2021 Jul;83:256-259. doi: 10.1016/j.sleep.2021.03.031. Epub 2021 Apr 6. PMID: 34049045. ↑

Planning and production

Author: Yu Zhouwei, attending physician of neurology, author of "Sleep Formula"

Reviewer: Zhao Wei, Chief Physician, Department of Neurology, Tianjin University TEDA Hospital