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Playing sounds synchronized to the rhythm of brain oscillations during sleep can significantly improve memory, according to a new small study.

Researchers explain that slow oscillations in the brain that occurs during slow-wave sleep are critical for retaining memories.  The study found that playing sounds matched to the rhythm of the slow brain oscillations of sleeping subjects enhanced these brain waves and improved their memory.

Based on the latest findings published in the journal Neuron, researchers say sound stimulation can be used as an easy and noninvasive way to improve sleep and enhance memory

"The beauty lies in the simplicity to apply auditory stimulation at low intensities-an approach that is both practical and ethical, if compared for example with electrical stimulation-and therefore portrays a straightforward tool for clinical settings to enhance sleep rhythms," researcher Dr. Jan Born, of the University of Tübingen, in Germany, said in a statement.

Researchers conducted their tests on 11 participants on different nights.  On some nights participants were exposed to sound stimulations and on others sham stimulations.

The findings revealed that when participants were exposed to sound stimulations that matched their brain's slow oscillation rhythm, they were significantly better at remembering word associations they learned the night before. However, researchers found that sound stimulations that did not match the brain's slow oscillation rhythm had no effect on memory.

"Importantly, the sound stimulation is effective only when the sounds occur in synchrony with the ongoing slow oscillation rhythm during deep sleep," Born said.

"We presented the acoustic stimuli whenever a slow oscillation 'up state' was upcoming, and in this way we were able to strengthen the slow oscillation, showing higher amplitude and occurring for longer periods," Born explained.

Besides giving people a memory boost, researchers believe sound stimulation could also help improve sleep and attention.

"Moreover, it might be even used to enhance other brain rhythms with obvious functional significance-like rhythms that occur during wakefulness and are involved in the regulation of attention," Born added.