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Are sound machines actually good for sleep?

Are those ocean waves or raindrops on the roof actually leading to worse sleep?

With the popularity of white noise machines and apps that play soothing sounds, such as raindrops on a roof and ocean waves, or actual white noise, you might think there’s firm proof that these sound-based sleep aids actually lull one into peaceful slumbers.

But a new review of past studies has found the evidence for that is quite thin. And while these aids might help a person doze off, there’s a hint that the sounds might ruin sleep later in the night if the app or machine isn’t shut off with a timer.

Are there benefits to white noise?

There certainly are plenty of theories to explain why white noise or soothing, low-pitched sounds might improve sleep.

They include:

  • The dull, meaningless sound might have calming properties that lull the brain to sleep.
  • Use of white noise night after night might become part of a person’s sleep ritual and, in a Pavlovian way, the sounds might cue people’s brains to start winding down.
  • The white noise, or other recorded sounds, might drown out annoying noise, such as honking horns or loud music emanating from a neighbor’s apartment, allowing the brain to ignore those irritants.

For the new study, researchers scoured the medical literature for studies that examined the impact of white noise on sleep. In the end, they turned up 38 studies, most quite small, that attempted to address the issue. The studies were all over the map in terms of methodology, too. Some used sleep labs to measure the impact of white noise, while others depended simply on participants’ self-reports on sleep quality.

The dearth of good evidence came as a surprise to study co-author, Dr. Mathias Basner, a professor in the department of psychiatry at the University of Pennsylvania Perelman School of Medicine in Philadelphia.

There was a suggestion in some of the studies that white noise might help a person doze off quicker, but there were also hints that white noise played throughout the night might result in fragmented sleep, Basner said.

Can white noise be harmful?

Why are so many people spending their hard earned dollars on apps and machines to play white noise throughout the night?

Though there isn’t good proof, it’s possible that the machines and apps do work for some people, Basner said. “There simply is not enough research out there, so we can neither conclude they work nor that they are harmful,” he added.

Besides, the white noise may be habit forming in its own way. “Once you have made the machines or apps as part of your sleep ritual, it can be hard changing your routine,” Basner said.

Basner worries that we may one day find that these white noise makers are harming our hearing. Just like our brains need down time, so must our ears, he explained. Until more is known, we should make sure the white noise is turned down as low as possible, he said.

Should kids use white noise?

The studies Basner and his colleagues reviewed included participants who varied widely in age, ranging from newborns to Alzheimer’s patients. Studies in babies suggested that white noise might shorten the time it takes a child to get to sleep.

That doesn’t surprise Dr. Harvey Karp, who has spent a lot of time researching what it takes to get babies to sleep.

“Babies are born with a very special reflex, a calming reflex, that is like an on switch for sleep,” said Karp, author of “The Happiest Baby on the Block.”

Karp’s five-step method for turning on that calming reflex includes using a type of white noise that emphasizes low frequencies.

“For (baby) sleep you want a low-pitched, rumbly white noise like that made by a train or a car,” Karp explained, adding that this kind of white noise will resonate with a baby because it is reminiscent of the sounds heard in the womb.

While babies lose the calming reflex as they get older, the same types of stimuli, such as low-pitched white noise and gentle rocking, still seem to tap into memories of the womb and to help us drop off to sleep even as adults, Karp said. It’s why many of us tend to fall asleep when we’re riding on trains, planes and cars, he added.

The bottom line:

While there's no hard proof that white noise is beneficial to sleep, there also isn't any evidence that it's harmful. So if it helps you doze off faster or stay asleep longer, that may be reason enough to stick with your routine. Though, as Basner noted, you might want to lower the volume.