Sleep helps consolidate our memory of complex associations, thereby supporting the ability to complete memories of entire events.

Researchers have known for some time that sleep strengthens our memories of facts and events. However, research to date has focused primarily on simple associations — that is, connections between elements, such as those we make when learning new words. “But in real life, events typically consist of multiple components — for example, a place, people, and objects — that are linked together in the brain,” says LMU’s Institute of Medical Psychology. Dr. Nicholas Lutz explains. These associations may vary in strength and some elements may be indirectly related to each other. “Thanks to the neural connections that underlie these associations, a single word is often all one needs to recall not just individual aspects of an event, but multiple aspects at once.” This process, known as pattern completion, is a fundamental feature of episodic memory. Lutz is the lead author of a study recently published in the journal Proceedings of the National Academy of Sciences (PNAS).who investigated the effect of sleep on memory for such complex events.

After study participants learned events with complex associations, in one condition they spent the night in a sleep laboratory, where they were allowed to sleep normally, while in another condition, they had to stay up all night. In both conditions, participants were allowed to spend the following night at home to recover. They were then tested on how well they could recall the various associations between the elements of the learned events. “We were able to show that sleep specifically strengthens weak associations and strengthens new associations between elements that were not directly connected to each other during learning. Q, after sleep this improved compared to the condition in which the participants remained awake,” summarizes Nicholas Lutz. This shows the importance of sleep for the completion of partial information and the processing of complex events in the brain.

By monitoring the brain activity of study participants during sleep, the study authors were also able to show that improvements in memory performance were associated with so-called sleep spindles – bursts of neural oscillatory activity during sleep. which active consolidation of memory contents. This occurs through reactivation of underlying neural structures during sleep. “This finding suggests that sleep spindles play an important role in the consolidation of complex associations, which lead to the completion of memories of entire events,” says the study’s lead researcher, Professor Luciana Besedowski.

According to Lutz and Besedovsky, the identified effects of sleep on memory can be seen as an important adaptation of the human brain, as it helps people to draw a more coherent picture of their environment, which in turn leads to the future. can make more comprehensive predictions about celebrations. “And so our results reveal a new function through which sleep may offer an evolutionary advantage,” says Luciana Besedowski. “Furthermore, they open up new perspectives on how we store and access information about complex multi-element events.”