Tight sleep can make our memories more accessible, according to a study by University of Exeter in Britain and the Basque Centre for Cognition, Brain and Language (BCBL), Spain. The study has been published in the journal Cortex.
"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," explained Nicolas Dumay from University of Exeter.
When scientists examined the subjects, in two situations subjects forgot information over the course of 12 hours of wakefulness and a night's sleep was shown to promote access to memory traces that had initially been too weak to be retrieved. The scientists tracked memories for novel, made-up words learnt either prior to a night's sleep, or an equivalent period of wakefulness. Subjects were asked to recall words immediately after exposure, and then again after the period of sleep or wakefulness.
The participants who have enough sleep memorised the words at immediate test and those who failed to recall the words are eventually remembered at retest.
The beneficial impact of sleep on memory was well established by this study. "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," Dumay said.