Researchers have uncovered the critical role of sleep in consolidating memories of complex events. The study by the LMU's Institute of Medical Psychology focused on the effect of sleep on memory of intricate associations within events.
Dr. Nicolas Lutz, lead author of the study published in the journal Proceedings of the National Academy of Sciences (PNAS), emphasised the significance of sleep in completing memories of whole events.
Participants who had learned events with complex associations were observed under two conditions: spending the night in a sleep laboratory or staying up all night. The subsequent night was spent at home to facilitate recovery before testing the participants on their ability to recall different associations between elements of the learned events.
"We were able to demonstrate that sleep specifically consolidates weak associations and strengthens new associations between elements that were not directly connected with each other during learning. Moreover, the ability to remember multiple elements of an event together, after having been presented with just a single cue, was improved after sleep compared to the condition in which the participants had stayed awake," said Nicolas Lutz.
The study also monitored the brain activity of the participants during sleep, revealing that the improvement in memory performance is connected with sleep spindles, bursts of neural oscillatory activity during sleep associated with the active consolidation of memory contents.
"This finding suggests that sleep spindles play an important role in the consolidation of complex associations, which underlie the completion of memories of whole events," said Professor Luciana Besedovsky, lead researcher of the study.
Overall, the study's findings shed light on the importance of sleep in completing partial information and processing complex events in the brain. Lutz and Besedovsky highlighted the identified effects of sleep on memory as an important adaptation of the human brain, helping individuals draw a more coherent picture of their environment and make more comprehensive predictions of future events.
"And so our results reveal a new function by which sleep can offer an evolutionary advantage," reckoned Luciana Besedovsky. "Furthermore, they open up new perspectives on how we store and access information about complex multielement events."