Most of us are familiar with white noise, the static sound at least one of our friends or family members listens to while they sleep. But many of us don't know that sound comes in different colors—like pink, blue and grey—and each one has its own properties and attracts our senses in a different way.
In recent years pink noise has caught the attention of researchers studying the connection between memory and sleep, with many believing it has the potential to improve our memory by impacting our brain activity while we sleep. And now, a new study published in Frontiers in Neuroscience tested the effect of pink noise on older adults and found that it did, in fact, improve memory—which could have important implications for memory and cognitive function.
Pink noise and slow wave activity for better sleep.
Pink noise—a mix of low and high frequencies—seems to be a particularly special type of noise; it's a slightly softer and more balanced version of white noise (making it less harsh and easier on our ears, which is why it's ideal for sleep) and sounds a lot like the rusting of leaves or the ocean. It's well known that deep sleep (also known as slow wave sleep) is particularly important when it comes to the intersection of sleep, aging, and memory. The purpose of this study was to better understand the link between slow wave sleep and cognitive function by using acoustic stimulation (pink noise) to try to increase slow wave activity (SWA) at intervals throughout the night. In other words: If the participants slept to the sound of pink noise and would it alter their brain activity during sleep and help with memory the next day?
Understanding the connection between sleep and memory.
For this study, thirteen people (ages 60 to 84) were exposed to one night of acoustic stimulation and one night of a sham stimulation. Their slow wave brain activity was recorded during the night and memory was tested before and after sleep. Results showed that acoustic stimulation increase SWA compared to the sham stimulation and overnight improvement in word recall was significantly greater (26 percent greater) with acoustic stimulation compared to the sham. Essentially, by delivering pink noise at the correct time the scientists were able to enhance SWA and sleep-dependent memory storage by 26 percent.
Suffering executive function and memory decline are unwelcome side effects of getting older, and as the 65-plus population continues to grow, understanding the reasons for this cognitive decline—and trying to prevent it—is becoming more and more important. So what does this mean for the younger crowd? While this study was performed in older adults, acoustic stimulation has also been shown to improve the memories of young people. If you're interested in trying out some pink noise, you can listen here. There are also ton of videos on YouTube and even full pink noise albums on iTunes. We think it's worth an experiment!