Think pink for better sleep and extra brain benefits.
While research is mixed about the benefits of background noise during sleep, many have added apps and ambient sound machines to nighttime routines for reduced clamor and improved rest.
And our brains could see a big benefit with sound machines — and one type of static noise in particular — helping give our noggins a good cleaning out.
Throughout the day, our brains accumulate waste and toxins (like lactic acid and worn-out proteins) that can be harmful if left to build up.
However, the brain’s glymphatic system uses waves of cerebrospinal fluid (CSF) to flush out waste, a process that conveniently happens during deep, non-REM sleep.
Without this “clean-up,” waste and toxins can trigger inflammation, disrupt communication between brain cells and eventually lead to neuron damage.
A recent study from MIT has found that tiny bursts of “pink noise” during sleep can increase the amplitude of slow electrical waves, which strengthens CSF waves.
Like white noise, pink noise is a steady background noise, often similar to ambient noise.
Pink noise, however, uses deeper sounds and lower frequencies to create a more even, flat sound, like steady rain or a distant waterfall.
The team behind the study wanted to explore the relationship between brain waves and CSF flow, and determine if manipulating the brain waves could enhance cerebrospinal fluid flow.
Earlier research has shown that auditory stimuli played at the peak of slow waves that occur during deep sleep can deepen CSF waves.
“Similar to a child on a swing, if you push them when they’re at the right moment in their movement, you can make that swing go farther,” senior study author Laura Lewis said in a press release. “The challenge is: How do you find just the right time?”
Testing 14 healthy participants, researchers delivered a 50-millisecond burst of pink noise at the slow wave peaks.
While the burst of noise wasn’t loud enough to wake the participants, it did increase the amplitude of both the slow electrical waves and the CSF waves during sleep.
Researchers also discovered that the slow waves stimulated blood vessels to constrict and widen, acting as a pump to drive out CSF from the brain.
Over time, the buildup of waste and toxins has been linked to cognitive decline, memory loss and neurodegenerative diseases such as Alzheimer’s.
The research team is hopeful that the findings of this study lead to more studies on increased CSF flow for improved sleep.
There’s also the potential to look further into how these brain waves play a role in the removal of waste from the brains of those with Alzheimer’s and other diseases characterized by the buildup of harmful proteins.
“Now that we can enhance CSF flow during sleep in healthy adults, we’re really excited to bring this technology to clinical populations to see what effects we can have,” Lewis said.
The study’s lead author, Joshua Levitt, has also started a company that hopes to develop a wearable device that would increase CSF flow by delivering an auditory stimulus at the right time.
