What’s your favorite bedtime jam? Do you doze off to jazz, a babbling brook, a crackling fire or a whirling fan of white noise? Or maybe you’re a sound aficionado, and have replaced your white noise machine with one that provides the more fashionable pink or brown noise?
Whatever your pleasure, know this: While continuously listening to low decibel calming sounds at night doesn’t appear to be harmful, there also isn’t much science behind how, why — or even if — sound machines help sleep.
“So many people are using it that the public health consequences of this are potentially ‘ginormous,’ yet right now we have little to no research on this,” said Dr. Mathias Basner, a professor in the division of sleep and chronobiology at the University of Pennsylvania School of Medicine, who published a systematic review of research on noise as a sleep aid.
“It’s possible that they could be beneficial for sleep, and it’s also plausible that they could be detrimental for sleep,” Basner said. “The evidence that we have is inconclusive and very low quality at this point.”
Regardless, sleep experts often hear patients vouch for the success of a soft, soothing hum in helping them fall and stay asleep, especially if they are anxious, have insomnia or live in a noisy, urban setting.
“White noise machines work through a process called sound masking or noise masking,” said Michael Grandner, who directs the Sleep and Health Research Program at the University of Arizona College of Medicine
“They create a blanket of sound around you that absorbs other sound waves so that little creaks and cracks and cars driving by don’t quite make it to your brain and you don’t respond to them,” Grandner said.
Another reason white noise or other sounds may induce sleep is that they have become part of your “sleep ritual,” those nighttime habits you do that have trained your brain to rest.
“Teddy bears don’t do anything but they help people sleep, they become a conditioned stimulus,” Grandner said. “Same thing with white noise — if someone turns it on every night, it becomes a bell that you start salivating to, or in this case something they fall asleep to every day.”