NEW YORK (Reuters Health) - Taking a 45-minute nap during the day appears to help the brain process some information to memory, research suggests.
"A nap has a beneficial effect on performance across multiple tasks, particularly for subjects who learned the material more strongly before sleep," Dr. Matthew Tucker told Reuters Health.
"In contrast, a nap does not have the same enhancing effect in subjects who learned poorly prior to sleep," said Tucker, of Beth Israel Deaconess Medical Center, in Boston, Massachusetts.
Tucker and colleagues tested how a 45-minute daytime nap, compared with no nap, influenced how well 11 male and 22 female undergraduate students were able to memorize factual and spatial information.
The students, all caffeine, alcohol, and medication-free, were aged 23 years on average when they attended a sleep laboratory at The City College of the City University of New York, in New York, to participate in the study.
According to a report in the journal Sleep, the students performed three tasks that required memorization. One involved linking 60 unrelated word pairs, such as tree-nose; another required maneuvering through a computerized maze; and the last gave students 5 minutes to copy a complex figure.
The researchers then randomly assigned students to individual sleep chambers where 16 napped and 17 rested quietly. After about 10 minutes, the no-nap group went to a separate room to watch television while the nappers completed their 45-minute sleep.
Two-hours later, after all the students watched the same movie, the researchers had students recall the word pairs, and measured their speed and accuracy in the computerized maze, as well as their ability to redraw the complex figure from memory.
Among the students deemed high-performers in the initial tests, those who napped performed better than non-nappers on all three tasks at the re-test. By contrast, naps did not enhance the memory among initially low-performing students, the researchers note.
The findings of this study, Tucker said, "clearly suggest that sleep, even in the form of a short daytime nap," helps the brain selectively process well-learned information.
A logical next step would be to look at the factors that produce enhanced learning and how these factors are associated with memory enhancement during sleep, Tucker added.
SOURCE: Sleep, February 2008
