Sleep not only protects memories from outside interferences, but also helps strengthen them, according to new research from the Harvard Medical School. A good night's sleep will help you to better remember specific facts, episodes and events.
The study: Forty-eight people between the ages of 18 and 30, all of whom had healthy, normal sleep routines and were not on any medication, were divided into four groups. Each group was taught the same list of 20 word pairs.
- Group 1 was taught the word pairings at 9 a.m. and tested at 9 p.m. after being awake for 12 hours.
- Group 2 was taught the word pairings at 9 a.m. and tested at 9 p.m. after being awake for 12 hours, but was given a second list of word pairs to remember right before the test.
- Group 3 was taught the word pairings at 9 p.m., slept all night and was then tested on the words at 9 a.m.
- Group 4 was taught the word pairings at 9 p.m., slept all night and was tested on the words at 9 a.m., but was given a second list of word pairs to remember right before the test.
Note: In the second list of word pairs, the first word in each pair was the same as on the first list, but the second word was different. This tested the brain's ability to handle competing information, which is known as interference. Participants in groups 2 and 4 were given tests on both lists of words.
The results: Those who slept after learning the information performed best, successfully recalling more words. Those in group 3, who slept after learning the words and were not given the second list or interference, were able to recall 12 percent more word pairings from that first list than those in group 1 who were awake for 12 hours after learning the words. With interference, the recall rate was 44 percent higher for the sleep group.
"This is the first study to show that sleep protects memories from interference," said lead study author Dr. Jeffrey Ellenbogen. "These results provide important insights into how the sleeping brain interacts with memories: it appears to strengthen them. Perhaps, then, sleep disorders might worsen memory problems seen in dementia."
The research findings were presented to the American Academy of Neurology's 2007 annual meeting in Boston, Massachusetts.
--From the Editors at Netscape
