How Important Is Sleep To Memory?

For the brain it may play a critical role in picking the good stuff and getting rid of the garbage, or “if you don’t get enough sleep it’ll be garbage in and garbage out the next time you take a test.”

And, if you’re a student – from the youngest ages through graduate school and beyond, after a good night’s sleep you will remember information better if you already know it will be useful in the future.

That’s the word from a research time led by Jan Born, PhD, of the University of Lubeck (Germany) and published in the February 2, 2011 issue of The Journal of Neuroscience.

The researchers found that the brain evaluates memories during sleep and preferentially retains the ones that are most relevant.

Just imagine all of the information the brain takes in every day – from all of the noise (commercials on TV and the radio) to spam and just plain misinformation on the Internet; useless phone numbers, meaningless comments by coworkers or classmates, and the critical little phrase from a professor: “This will be on the final exam.” Retaining all of it would make picking and choosing what is important much more difficult, especially when you sit down to a critical test or important board meeting.

The German researchers attempted to discover how the brain decides what to keep and what to ditch. “Our results show that memory consolidation during sleep involves a basic selection process that determines which of the many pieces of the day’s information is sent to long-term storage,” reports Born. “[I]nformation relevant for future demands is selected foremost for storage.”

Researchers set up two experiments to test memory retrieval in a total of 191 volunteers. In the first experiment, participants were asked to learn 40 pairs of words; in the second participants played a card game matching pictures of animals and objects – similar to the game “Concentration” – and practiced sequences of finger taps.

Half the volunteers were told immediately that they would be tested in 10 hours; in the end, all participants were tested on how well they recalled their tasks. People who were allowed to sleep between the time they learned the tasks and the tests performed better than those who did not sleep. More importantly, only the volunteers who slept and knew they would be tested had substantially improved memory recall.

Researchers also found that “The more slow wave (brain) activity the sleeping participants had, the better their memory was during the recall test 10 hours later,” according to Born. As a result of this study, the authors suggest that the brain’s prefrontal cortex “tags” memories deemed relevant while awake and the hippocampus consolidates these memories during sleep.

“These results suggest that sleep is critical to this memory enhancement,” notes Gilles Einstein, PhD, an expert in memory at Furman University. The new study helps to explain why a student is more likely to remember material from a lecture than small talk on the way to class. “This benefit extends to both declarative memories (memories about a lecture) and procedural memories (memory for a new dance step.”

-Dr. Francis Flynn

Posted in: Sleep Issues

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