Sleep helps to strengthen both old and new versions of an experience, new research shows.
Instead of overwriting old versions of a memory, the brain stores another copy of the same experience.
Sleep keeps both old and new memories alive, which gives memory more flexibility.
Dr Scott Cairney, who led the research said:
“Previous studies have shown sleep’s importance for memory.
Our research takes this a step further by demonstrating that sleep strengthens both old and new versions of an experience, helping us to use our memories adaptively.
In this way, sleep is allowing us to use our memory in the most efficient way possible, enabling us to update our knowledge of the world and to adapt our memories for future experiences.”
For the study people were learning the locations of words on a screen over two learning sessions.
One group slept between learning sessions for 90 minutes, the other did not.
The catch was that some of the words moved between training session.
Those that slept in between had better memory for both the original location and the updated location.
This suggested sleep had had a positive effect on both the new and old version of the memory.
Professor Gareth Gaskell, study co-author, said:
“For the sleep group, we found that sleep strengthened both their memory of the original location as well as the new location.
In this way, we were able to demonstrate that sleep benefits all the multiple representations of the same experience in our brain.”
Curiously, the study may also show how some inaccuracies in memories arise.
After all, if we are carrying around multiple memories of the same thing, then it is easy for us to get confused.
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The study was published in the journal Cortex (Cairney et al., 2017).