You’ve heard of white noise, but wait till you hear its cousin.
A new study published in Frontiers in Human Neuroscience found that older adults can achieve deeper sleep and stronger memories by listening to ‘pink noise’ – a sound characterized by a mixture of high and low frequencies said to be more balanced and natural than white noise.
Previous studies have found that playing pink noise during sleep enhances the memory of younger adults.
“We wanted to see if it would work in older people, too,” said author Dr. Phyllis Zee of Northwestern University Feinberg School of Medicine, adding that older folks tend to get less slow-wave sleep that can negatively impact memory.
Researchers had 13 adults over 60 spend two nights in a sleep lab. On both nights, participants took a memory test, went to sleep with headphones and an electrode cap, and completed the same memory test in the morning.
One night, headphone-wearing participants were played a series of short bursts of pink noise during deep sleep, timed in such a way that kept the brain from adapting to them or ignoring them.
“The noise is fairly pleasant; it kind of resembles a rush of water,” says Zee. “It’s just noticeable enough that the brain realizes it’s there, but not enough to disturb sleep.”
The sounds were spaced out to match their slow-wave oscillations. No sounds were played for the participants during the other night.
Researchers then examined all participants’ sleep waves and found that the slow-wave oscillations increased on the nights when pink noise was played. In the morning, those who had listened to pink noise performed three times better on memory tests than they had the other night. On the nights without pink noise, memory recall didn’t improve as much.
While Northwestern has a patent pending on the new technology and one of the study authors plans to market it commercially, Zee said further research is needed to confirm the findings and show that pink noise holds long-term benefits.
Zee said as far as they know at this point is that pink noise’s effectiveness is all about the timing.
“The effect here, at least for memory, is quite related to the ability of the sound stimulus to enhance slow-wave sleep,” she said.
“That’s very much tied to what part of the slow wave the stimulus is hitting on.”
The researchers hope to eventually develop an official (and affordable) pink noise device that people can use at home. In the meantime, Zee said there are other soothing sounds with numerous benefits available via apps and gadgets. Music, nature sounds and white (or even pink) noise apps can help improve sleep.
Check out an example of pink noise (and try not to fall into a deep slumber) below: