Struggling to remember something? Have a good sleep, as researchers find it boosts memory
Scientists show for first time that sleep makes it easier to retrieve nuggets of information that may have got lost in a corner of the brain
By Agency / 12:01AM BST 27 Jul 2015
If you are trying to remember something vital you have forgotten, get a good night’s sleep.
It is well known that sleep boosts memory, but scientists have shown for the first time it also makes it easier to retrieve nuggets of information that may have got lost in a corner of our brain.
In two situations where subjects forgot information over the course of 12 hours of being awake, after a night’s sleep they were about twice as likely to be able to remember it.
Psychologist Dr Nicolas Dumay, of the University of Exeter, said: “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.”
The finding, published in Cortex, means sleeping not only protects memories from being forgotten, it also makes them easier to access because we are more likely to recall facts that we could not remember while still awake.
The finding, published in Cortex, means sleeping not only protects memories from being forgotten, it also makes them easier to access because we are more likely to recall facts that we could not remember while still awake.
In the study, Dr Dumay analysed two previous research papers involving a total of 123 participants whose memories were tracked for made-up words such as “frenzilk” and “caravoth”.
The words were learnt either prior to a night’s sleep, or an equivalent period of wakefulness, with subjects asked to recall them immediately after exposure, and then again after a sleep – or the same period of wakefulness.
The key distinction was between those word memories that participants could recall at both the immediate test and the 12-hour retest, and those not remembered at test, but eventually remembered at retest.
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Dr Dumay found that, compared to daytime wakefulness, sleep helped rescue unrecalled memories more than it prevented memory loss. This is at odds with previous research that has argued sleep only protects against memory loss.
He said: “Sleep improves the accessibility of memories more than it protects them against interference.
“In two studies in which net recall/recognition showed forgetting after 12 hours of wake, analyses revealed post sleep advantage was predominantly due to sleep promoting access to memory traces that had initially been too weak to be retrieved.”
Dr Dumay said it means memories can be “sharpened overnight”, and he believes the boost comes from the hippocampus, an inner structure of the temporal lobe unzipping recent episodes and replaying them to regions of the brain originally involved in their capture – this would lead the subject to effectively re experience the major events of the day.
He added: “The beneficial impact of sleep on memory is well established, and the act of sleeping is known to help us remember the things that we did, or heard, the previous day.
“The idea that memories could also be sharpened and made more vivid and accessible overnight, however, is yet to be fully explored.”
Last year, brain scans on mice found for the first time that new connections between brain cells – synapses – form during sleep. The study showed even intense training could not make up for lost sleep. Experts said it uncovered the mechanisms of memory.
It is well known that sleep plays an important role in memory and learning. But what actually happens inside the brain has been a source of considerable debate.
