A new study has found that certain sounds in your sleep can enhance memories when you wake up.

While such as ginko biloba may help with improving memory, a study from Northwestern University indicates that even though the participants were in a deep sleep, they were able to hear sounds that enhanced their memory when they awoke.

The study played 25 different sounds while the participants slept, including a cat meowing and a tea kettle whistle.

Previously, the participants were asked to drag matching objects across a computer screen as a way of spatial learning. It was found the participants were more accurate in the exercise their nap with the sounds.

Researchers believe that this study may be key in determining how sleep affects memory retention.

“We are beginning to see that deep sleep actually is a key time for memory processing,” said senior author Ken Paller.

Paller added that this study will open the door to many questions and that further research is needed to understand how memory process during the sleep stage.