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"Sleeping On It"  Enhances Memory

Sleep deprivation affects our ability to remember and perform complex tasks. Harvard University neurologist Jeffrey Ellenbogen wondered if getting enough sleep had the opposite effect.

He had 48 people learn pairs of words in the evening. "Combinations like blanket-baseball, lamp-chair and so forth," Ellenbogen says, "Then they went to sleep and then in the morning, we had them learn an entire new list of words right before recalling the list they had learned before they went to sleep." Teaching the subjects another list of words in the morning was intended to distract them from remembering the words learned the night before.

Ellenbogen then took a different group of people and taught them a list of words in the morning. Both groups were tested on how well they remembered their lists later in the day. He found that the first group had better recall of words learned the night before than those who'd learned words that day, even after researchers tried to confuse the sleepers with new information. "The people that did their normal routine day were able to remember about 40 percent of the words," he reports. "But the people who slept were able to remember about 75 percent, so there was a very large difference between the ability to recall information after sleep compared to the ability to recall information after a normal routine waking day."

He says he finds that remarkable, adding, "what we think is really going on, is that sleep leads to boosts in memory, but most people aren't aware of that boost unless you test it in the right way."

Ellenbogen will be presenting his research at the annual meeting of the American Academy of Neurology, taking place next week [April 28-May 2] in Boston.