How Sleep Makes You Smarter

Planning to stay up all night and cram for an exam? Think again. Sleep improves memory and alertness, and lack of it makes it harder to use your smarts. Why? Science isn't entirely sure why adequate sleep is so necessary for proper brain function, but research is beginning to uncover how the mind works to turn experience into robust memories.

Reduced False Memory after Sleep

A new study by Kimberly Fenn of Michigan State University suggests that lack of sleep increases the likelihood of making errors when trying to remember.

In Fenn's study, published in the September 2009 issue of the scientific journal Learning & Memory, subjects were shown a list of words, and then, 12 hours later, asked to recall them. Sleep was the study variable.

One group of subjects was shown the list of words at 10am and then, at 10pm the same day, were then presented with a larger groups of word, asked to identify only the words that they had seen that morning; somewhat like the granddaddy of multiple choice tests, correct answers mixed in with incorrect decoys. The other group of subjects was shown the list at night, and then, the next morning, after getting at least six hour of sleep, were asked to identify the words from the original list.

Results revealed that the students who did not sleep before being tested, were more apt to select words that were not on the original list; meaning they were more likely to have false memories or errors in memory.

Sleep Protects Older Memories from Being Displaced by New Memories

Scientists still aren't sure exactly what happens during sleep that makes memories stronger, but Dr. Jeffrey Ellenbogen of Harvard University believes that the brain firms up or rehearses newly acquired information during sleep.

In 2006 he was one of the researchers involved in a study similar to Dr. Fenn's recent research. Adults were given a word list to remember. Half of the study subjects slept before their memories were tested, while the other half did not.

To make the task more difficult, half of the members of each study group were shown another, unrelated list of words, to try and muddle their memory before being tested on the original word list. Regardless of the difficulty of the task, the group that got a good night's sleep before being tested did significantly better.

Ellenbogen concluded that sleep may help solidify actual memories and make the mind more resistant to mistakes in recall.

Bottom line-Pulling an all-nighter is not the way to score high grades. Sleep allows your brain to rehearse the information that you've studied. So to get good marks, let your brain do some of the work for you, and study while you sleep.

Sources

Fenn, K.; Gallo, D.; Margoliash, D.; Roediger, H.; Nusbaum, H. (2009). "Reduced false memory after sleep." Learning & Memory, Volume 16, Issue, 9.

Ellenbogen, J,; Hulbert, J.; Stickgold, R.; Dinges, D.; Thomson-Schill, S. (2006) "Interfering with Theories of Sleep and Memory: Sleep, Declarative Memory, and Associative Interference.", Current Biology, Volume 16, Issue 13.