Our Brains Chose Rewarded Experiences to Replay in Sleep

A new study shows that human brains, when choosing the experiences to “replay” during sleep in the process of creating memories, select rewarded life experiences over others. 

Memory consolidation or the transformation of an experience into a long-lasting memory is one of the most important processes that take place during sleep, specifically, during the slow-wave sleep phase (SWS). Memory consolidation helps us learn new things and acquire new skills.

But before an experience gets transformed into a memory, it needs to get selected. In that way, useful information is preserved, while the experiences our brains judge to be useless are forgotten. The only question is: How does the human brain make the difference between these two?

A research team at the University of Geneva in Switzerland led by Virginie Sterpenich conducted a study to find this out. 

In the study, the participants were required to play two video games that activated different regions of their brain. Then, their brain activity was measured during sleep with functional MRI.   

Results showed that our brains are more inclined to replay and process such life experiences that led to a reward (winning at a complex game) than those with a negative outcome. 

Scientists believe that this happens because of the evolutionary advantage we get when remembering these. Rewarded experiences are those in which we satisfied some of our physiological or psychological needs. So, because these memories might serve our survival in the future, they get prioritized.

In the study, rewarded experiences would reemerge in participants’ MRI spontaneously during sleep and were associated with a better performance the next day. 

Also, researchers concluded that these memory-producing replays could be induced by external triggers, stimuli like smells, or music during NREM sleep. This is why using quality essential oils will not only help you fall asleep but can also facilitate the creation of memories.