"Sleeping on it" may have new meaning if researchers from the University of Exeter (in the United Kingdom) and the Basque Centre for Cognition, Brain and Language (in Spain) are right. These researchers, whose study was published in Cortex and reported in Bioscience Technology, say that sleeping keeps memories from being forgotten and makes them easier to recall (http://www.biosciencetechnology.com/news/2015/07/sleep-makes-our-memories-more-accessible-study-shows?et_cid=4695720&et_rid=45505806&location=top).
Although the connection between sleep and memory is not clear, scientists are studying the way in which sleep benefits the brain and individual neurons, as well as sleep's function in learning and creative insight. They also want to understand the impact of chronic sleep loss on memory and to help the body and mind recover from sleep loss (http://www.brainfacts.org/sensing-thinking-behaving/sleep/articles/2015/the-secret-to-memory-a-good-nights-sleep/).
The new research concludes that after sleep, people are more likely to recall facts that they could not remember when still awake. In two situations where study subjects did not remember information during a period of 12 hours of wakefulness, a night's sleep enabled them to access memory traces that "had been too weak to be retrieved," the article explains. The research followed memories for "novel, made-up words" learned either before a night's sleep, or an equivalent period of being awake. Researchers requested that study subjects recall words right after exposure and then again after a period of sleep or being awake. The major distinction was between word memories that subjects could remember "at both the immediate test and the 12-hour retest, and those not remembered at test, but eventually remembered at retest." Sleep helped participants to retrieve memories more than it prevented memory loss.
According to Nicolas Dumay, an experimental psychologist at the University of Exeter and an honorary Staff Scientist at the Basque Centre for Cognition, Brain and Language (BCBL), "Sleep almost doubles our chances of remembering previously unrecalled material. The post-sleep boost in memory accessibility may indicate that some memories are sharpened overnight. This supports the notion that, while asleep, we actively rehearse information flagged as important. More research is needed into the functional significance of this rehearsal and whether, for instance, it allows memories to be accessible in a wider range of contexts, hence making them more useful."
Sleep's beneficial impact on memory is well documented, and the act of sleeping helps us to remember the things that we did, or heard, the previous day. The researchers want to explore the idea that memories could also be sharpened and made more vivid and accessible overnight. According to Dr. Dumay, the memory boost comes from the hippocampus, unleashing recently encoded occurrences, replaying them to regions of the brain originally involved in their capture and letting the subject re-experience them.