Participants in the study learned novel, made-up words. The researchers tested their ability to recall the words right after exposure and again, 12 hours later. Some of the participants slept during the 12-hour period between tests, while others stayed awake the entire time. The researchers were especially interested to find out if there were words that the participants did not recall during the first test, but did recall during the second.
The participants who slept between tests had stronger recall than those who stayed awake. Sleeping between testing sessions led allowed participants to recall some words that they did not recall during the initial test. Sleep rescued unrecalled memories and prevented memory loss more than staying awake.
“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,” explained Nicolas Dumay, experimental psychologist at the University of Exeter.
The study suggests that people are most likely to recall information after sleep. It provides evidence for the idea that sleep not only aids in memory consolidation, but also sharpens memories.
This research is published in the journal Cortex.
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