Listening to Certain Sounds Before Sleep Increases Overnight Memory Retention

Over the years, small studies have shown that applying certain sounds can not only improve the quality of your sleep, but increase overnight memory retention.

In a recent study, German researchers recruited 11 subjects to sleep for two nights in a lab that monitored their sleeping patterns. During one night, the researchers played "pink noise" that was synchronized to their brain rhythms. As a control, no sounders were played the other nights, each as the participants were approaching deep sleep.

While the study shows that this didn't cause the participants to experience more deep sleep cycles, the pink noise appeared to prolong deep sleep and to increase the size of the subject's brain waves during that period, as evinced by their EEGs.

Slow brain waves that are known for characterizing deep sleep are implicated in information processing and memory formation that was seen the following morning for the participants. The morning after, their brain waves appeared to have been enhanced and they remembered a higher number of word pairs, according to the study, with an average of 22 as opposed to 13.

These practices were unsuccessfully tried before, using sound stimulation to stimulate sleep waves in participants. However, researchers note that the key is the frequency of sounds in sync with a subject's brain waves. If this technique were to be developed further, it could potentially be used to improve sleep in general, and possibly even to enhance brain activity when we're awake. Some people that this could be used as a way of treating Alzheimer's, fighting depression, easing pain and possibly to boost creativity. 

The study is published in "Auditory Closed-Loop Stimulation of the Sleep Slow Oscillation Enhances Memory" in Neuron.