White noise is alleged to mask disruptive noises in one’s bedroom environment and is used as a non-pharmacological approach for promoting sleep and improving sleep quality.
In the systematic review, published in the journal Sleep Medicine Reviews, Mathias Basner, a professor of psychiatry at the University of Pennsylvania School of Medicine, along with colleagues Samantha M. Riedy, Michael G. Smith and Sarah Rocha, analyzed the scientific literature and identified 38 studies about continuous white noise as a sleep aid.
Their findings on the topic were mixed. The researchers identified some evidence among the selected studies of continuous noise helping people fall asleep more quickly, but most of that evidence was of low quality. Furthermore, at least one study found that such noise might actually disrupt sleep.
In their review, the researchers noted that “the quality of evidence for continuous noise improving sleep was very low, which contradicts its widespread use.”
“If these apps or devices could only do good things, I wouldn’t really care. But because there may be negative consequences, I would just be careful,” Basner told The Guardian. “I wouldn’t broadly recommend them, because there is no evidence that they are actually working.”
Although there have not been tests on the subject, Basner is also concerned about the potential effects of not allowing such noise systems to switch off overnight.
“Whenever we’re exposed to sounds and noise, the inner ear is translating that into nerve signals that are then interpreted by the brain,” he stated. “It is an active process, which generates metabolites, some of which have been shown to be harmful to the inner ear. You probably want to have a period where the auditory system can wind down, regenerate and prepare for the next wake period.”
The clinical review noted that “additional research with objective sleep measures and detailed descriptions of noise exposure is needed before promoting continuous noise as a sleep aid, especially since it may also negatively affect sleep and hearing."