In a busy world, a good night's sleep has become difficult to come by, leading people to download any of the white noise apps available today. But a new study claims that this method is not as good as it appears to be.

White noise, familiar to most people as the hissing sound that accompanies TV static, actually comes from a variety of natural and man-made sources. In the age of smartphones, this particular noise has found a new use through numerous applications and gadgets that emulate "relaxing sounds," like the whirring of a fan or the humming of an air conditioning unit. One app, the Bedtime Fan for iOS, has enjoyed more than 3 million downloads. For Android users, the White Noise Generator has also crossed the one million download mark.

Lack of Conclusive Evidence

A new study from the School of Medicine at the University of Pennsylvania, conducted a systematic review - covering 38 studies - revolving around the efficacy of using noise to help achieve sleep. Their analysis revealed that though there was documented evidence of continuous noise reducing the time required to put participants to sleep, researchers of this new study found the evidence to be poor, with one study suggesting that noise may actually cause more disrupted sleep.

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The University of Pennsylvania researchers noted the lack of consistency in parameters used in the studies - from the characteristics of the noise, methodologies in measuring the participants' sleep quality, and even intervention measures taken in the reviewed studies.

Using the GRADE criteria - a method for the systematic review of evidence in research studies - researchers claimed that the quality of evidence reviewed was "very low," adding that this actually contradicts the widespread use of noise as a sleeping aid.

"If these apps or devices could only do good things," explained Mathias Basner, an author in the study and a psychiatry professor. "I wouldn't really care. But because there may be negative consequences, I would just be careful."

In a statement to The Guardian, Basner said that he would not "broadly recommend" apps that use this kind of noise, adding that there is no evidence that these actually work.

Let Your Ears Rest Too

One of the concerns Basner explained is the potentially negative effects of not letting humans rest their auditory systems with these apps. He added, however, that these negative effects have not yet been identified, much less tested with a formal study. He explained that exposure to noise makes the inner ear translate sounds into nerve signals to be interpreted by the brain, describing it as an active process. He said that it "generates metabolites, some of which have been shown to be harmful to the inner ear." Basner then recommended giving time to let the auditory system relax and regenerate in preparation for the next waking period.

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Other scientists not involved with the study concur with existing studies on providing continuous noise for sleep. Colin Espie, a sleep medicine professor from the University of Oxford, noted that the notion is a "very limited one conceptually." He explained that the main challenge to achieving sleep is the busy mind, especially for people having difficulty in switching off, mentally.

"White noise is just like any other monotonous stimulation," Espie said, adding that the noise has been tried many times over the years, with the evidence being poor.

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