Naps Can Help Save Positive Memories
More good news about afternoon naps. Researchers at the University of Geneva say that a daytime nap can help your brain solidify positive memories. .
Scientists already knew that sleep strengthens memories, but this new study suggests that it also helps select and retain memories that have a rewarding value.
The research team looked at 31 healthy volunteers and randomly assigned them to either a “sleep” group or a “wake” group. Both groups were asked to look at and remember eight pairs of pictures. They were informed that there would be a higher reward for remembering a specific set of pairs.
For the next phase, both groups had a 90-minute break during which people in the sleep group napped while the others didn't.
After the break, both groups were given memory tests of the picture pairs and were asked to estimate how confident they felt about their memory.
After three months, both groups were given a random test in which they were again asked to remember the same picture pairs and rate their score of confidence.
The results of the initial memory test showed that the napping group performed better overall, but with the more highly rewarded picture pairs, both groups performed equally well. Three months later, however, the sleep group showed better memory performance for the highly rewarded picture pairs than the wake group. Additionally, the sleep group reported higher levels of confidence in answering correctly.
Participants in each group also underwent magnetic resonance imaging (MRI) scans of their brains. The MRIs revealed that the sleep group had more activity in the hippocampus – the area of the brain responsible for forming memories - and also had increased connectivity between the hippocampus and the prefrontal cortex and the striatum – the areas involved in memory consolidation and reward processing.
The results suggest that rewards act as a kind of tag, telling the brain to favor that information over low-reward information, and to turn it into a long-term memory.