More than a quarter of Americans have trouble falling asleep or staying asleep, and over two-thirds struggle with sleep at least once a week. For these people, listening to white noise can help.
However, a different device has arrived on the scene that may be even more effective than white noise devices. Not only does it increase the time spent in deep sleep, it dramatically improves memory and may even stave off dementia.
Move over white noise, pink noise is here.
Like white noise, pink noise consists of all the various frequencies that humans can hear, from 20 hertz to 20,000 hertz.
But unlike white noise, where the energy is distributed equally across the sound spectrum, pink noise is more intense at lower frequencies.
Pink noise is found plentifully in nature, such as the sound of falling rain, rustling leaves or gentle ocean waves. White noise, on the other hand, is the crackling radio or television static you hear when the device is tuned to an unused channel. It can help you fall asleep faster by drowning out loud sounds that stimulate the brain and keep you awake.
Relieves Stress, Deepens Sleep
Pink noise’s effects on sleep weren’t known until the early 1990s, when Japanese researchers carried out several studies. These showed pink noise can induce and deepen sleep. The scientists suggested pink noise might be useful for people who suffer insomnia caused by work-related stress.
Almost 20 years passed before researchers from China picked up the gauntlet, comparing the effect of pink noise against no noise in 40 subjects. They found steady pink noise reduced brain wave complexity, induced more stable sleep and improved sleep quality.
Several other studies showed pulses of pink noise improved memory in young adults. This led neurologists from the Feinberg School of Medicine, Northwestern University, Chicago, to wonder whether the same benefit would occur in older adults.
Triples Ability to Recall Words
One of the reasons older folks are at greater risk of memory impairment is because they tend to get less deep sleep, or slow wave sleep.
This is the deepest phase of non-rapid eye movement (NREM) sleep, where dreaming occurs. It’s also important for memory consolidation. Pink noise is believed to be more valuable in inducing this form of sleep, and therefore, beneficial to memory.
To test this, in 2017, the Feinberg team enrolled 13 volunteers aged 60 and older to receive one night of acoustic stimulation and one night of sham stimulation (or no stimulation). Before each session they took memory tests and then again, the following morning.
The findings were dramatic. Compared to sham, pink noise tripled the ability to recall words.
Senior author, professor Phyllis Zee, said, “This is an innovative, simple and safe non-medication approach that may help improve brain health. This is a potential tool for enhancing memory in older populations and attenuating normal age-related memory decline.”
Improves Memory in the Cognitively Impaired
Two years later the Feinberg team followed this up with a study in nine people with the average age 72, who suffered from mild cognitive impairment. It was similar to the first experiment except that it took place over two nights one week apart.
The researchers found that acoustic stimulation increased slow wave activity within the brain by at least ten percent compared to sham—or no— stimulation.
Some participants experienced a sizable 40 percent increase in slow wave activity from pink noise and recalled nine more words in the word test. Others experienced a 20 percent increase in slow wave activity and recalled two more words in the word test.
Prof. Zee’s colleague, RonellMalkani, explained, “Our findings suggest slow-wave or deep sleep is a viable and potentially important therapeutic target in people with mild cognitive impairment. The results deepen our understanding of the importance of sleep in memory, even when there’s memory loss.
“These results suggest that improving sleep is a promising novel approach to stave off dementia.
“As a potential treatment, this would be something people could do every night.”
Should You Use Pink Noise?
The studies of pink noise to date are very small and the findings need to be confirmed in larger, longer and more robust trials.
What’s more, these scientists used a new scientific pink noise device. It read an individual’s brain waves in real time and locked in the gentle sound stimulation during a precise moment of neuron communication during deep sleep, which varies for each person.
Scientists hope to make this new technology available for home use, but they’re not ready to roll it out just yet.
Even so, for those who suffer with sleep problems it may be worth listening to ordinary pink noise at bedtime. Various sound machines, streaming services and smartphone apps that play pink noise are available.