A burst of “pink noise” may lead to more restorative sleep

Recent research conducted by MIT researchers indicates that exposure to short bursts of a gentle sound called "pink noise" during sleep may improve the effectiveness of cerebrospinal fluid (CSF) washing away waste products from the brain. This method, which has not been explored before, was found to increase the amplitude of slow electrical waves in the brain, thereby enlarging the CSF waves.

In a study published in Science Translational Medicine, MIT researchers Laura Lewis and Joshua Levitt demonstrated that by delivering these pink noise bursts during the brain's slow wave peaks, CSF flow could be enhanced. The auditory stimulus used was a 50-millisecond burst of pink noise, known for its balanced, gentle sound akin to rainfall or a distant waterfall.

The researchers managed to time the pink noise delivery with the slow wave peaks in the brain, overcoming the challenge of synchronizing the signals from EEG and fMRI scans.

The results of tests on 14 healthy volunteers showed that the pink noise stimulus increased both the amplitude of slow waves and the CSF waves during sleep. This enhancement in CSF flow could potentially boost cognitive function, memory, or even slow down the progression of neurodegenerative diseases such as Alzheimer's, which are partly caused by the accumulation of harmful proteins like amyloid beta.

The research team is now hoping to bring this technology to clinical populations to investigate its effects in these populations. They also aim to explore whether enhancing CSF flow and waste clearance could benefit individuals with Alzheimer's and other diseases characterized by protein accumulation.