According to researchers at the University of Exeter and the Basque Centre for Cognition, Brain and Language, sleep not only reserves memories, but also facilitates their access later on. These findings demonstrate that getting the right amount of sleep can help recall facts, which we would otherwise forget.

Sleep: More Than Just Memory Retention

Previous studies have established the advantageous impact that sleep has on memory. Sleeping is known to facilitate recalling things we have done or heard. 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), in Spain, wanted to learn more. He tested the idea that sleep could also sharpen memory – make it more vivid and accessible.

Testing The Idea: Sleep Makes Our Memories More Accessible

The study tracked memories for unique, made-up words that were either learnt before going to sleep, or after an equal time-period of staying awake. Participants were asked to recall the words immediately after having heard them, and then again after a night’s sleep or period of wakefulness.

Dr Dumay observed that, in comparison to wakefulness, a night of complete rest helped save unrecalled memories to a greater extent than just preventing memory loss. The significant difference was between words that could be recalled after immediate and 12-hour retest, and those which could only be recalled at retest.

In two scenarios where participants could not recall information after 12 hours of staying awake, a similar amount of sleep prompted access to memory traces that were initially too weak to be recalled and retrieved.

Explaining The Findings

“Sleep almost doubles our chances of remembering previously unrecalled material. It not only protects memories against forgetting, it also makes them more accessible”, Dr Dumay states in his research published in the journal Cortex. He suggests that a sufficient amount of sleep boosts memory accessibility – certain memories are sharpened overnight.

This corroborates the idea that as we sleep, our brain actively rehearses the information that is marked as being important. However, more research into the functional aspects of this mechanism are required; for instance, how memories are made more accessible in a larger context, making them more valuable.

Dr Dumay believes that the phenomenon is associated with the hippocampus – a structure found in the inner side of the temporal lobe. He suggests that the hippocampus may be involved in decoding retained occurrences and replaying them to specific region of the brain. This would lead to an effective re-experience of the event by the individual.