Sleep to Remember

If you find yourself forgetting detailed instructions from your boss or the time of an important business meeting, you might try remedying the problem with a good night’s rest.

 
Sleeping not only protects memories from being forgotten, it also makes them easier to access, according to new research from the University of Exeter and the Basque Centre for Cognition, Brain and Language The findings suggest that after sleep we are more likely to recall facts which we could not remember while still awake.

In two situations where subjects forgot information over the course of 12 hours of wakefulness, a night’s sleep was shown to promote access to memory traces that had initially been too weak to be retrieved.

The research, published in the journal Cortex, tracked memories for novel, made-up words learned 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 key distinction was between those word memories which participants could remember at both the immediate test and the 12-hour retest, and those not remembered at test, but eventually remembered at retest.

The researcher found that, compared to daytime wakefulness, sleep helped rescue unrecalled memories more than it prevented memory loss.

“Sleep almost doubles our chances of remembering previously unrecalled material,” experimental psychologist Nicolas Dumay of the University of Exeter explains. “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.”

Dumay believes the memory boost comes from the hippocampus, an inner structure of the temporal lobe, unzipping recently encoded 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.

“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,” he writes.