Aaaah, sleep. Research shows that not getting enough of the stuff can contribute to weight gain, crabbiness, high blood pressure and even an impaired immune system. But the latest study shows a more "intelligent" reason to sleep: Some people's memories are strengthened while they doze.
Michigan State University researchers studied the memory and sleep of 250 people and found that sleeping seems to improve memories in some people, in a yet-to-be-defined way that might not be able to be demonstrated on an intelligence or aptitude test like the SAT.
"We speculate that we may be investigating a separate form of memory, distinct from traditional memory systems," study researcher Kimberly Fenn, assistant professor of psychology, said in a statement. "There is substantial evidence that during sleep, your brain is processing information without your awareness and this ability may contribute to memory in a waking state."
This form of memory is called working memory capacity, or WMC, and researchers wrote in the study that it could "contribute substantially to individual differences in online processing," that is then a predictor of how well a person can then problem-solve, learn vocabulary, make decisions and comprehend reading passages.
From the study:
... There was a significant, positive correlation between WMC and increase in memory performance after sleep but not after a period of wakefulness.
Now, more studies must be done to see if the sort of improved memory witnessed in the study is actually translatable to better learning in school or elsewhere, researchers said.
This isn't the first research to link sleep with memory. While most studies have ruled out that listening to things as you sleep helps you to retain that information, a 2009 study in the journal Science showed that sleep helped to strengthen existing (but not new) memories in people, ABC News reported.
"Our memory systems are still active while we're asleep. Memories can be strengthened while we're asleep," study researcher John Rudoy, a doctoral student in neuroscience at Northwestern University, told ABC News.
And in a very small study last year in the journal Current Biology, The New York Times reported that people who dreamed while taking a nap did better afterward at completing a maze, compared with people who just napped but didn't dream, or people who didn't nap at all.