Naps Help Your Memory, New Study Suggests

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Naps Help Your Memory, New Study Suggests

http://www.sciencedaily.com/releases/2008/01/080107110401.htm

A ninety minute daytime nap helps speed up the process of long term

memory consolidation, a recent study conducted by Prof. Avi Karni

and Dr. Korman of the Center for Brain and Behavior Research

at the University of Haifa found. " We still don't know the exact

mechanism of the memory process that occurs during sleep, but the

results of this research suggest the possibility that it is possible

to speed up memory consolidation, and in the future, we may be able

to do it artificially, " said Prof. Karni.

Long term memory is defined as a permanent memory that doesn't

disappear or that disappears after many years. This part of our

memory is divided into two types -- memories of " what " (for example:

what happened yesterday or what one remembers from an article one

read yesterday) and memories of " how to " (for example: how to read

Hebrew, how to drive, play basketball or play the piano).

In this new research, which was conducted by researchers at the

University of Haifa in cooperation with the Sleep Laboratory at the

Sheba Medical Center and researchers from the Department of

Psychology at the University of Montreal, it was revealed that a

daytime nap changes the course of consolidation in the brain. Two

groups of participants in the study practiced a repeated motor

activity which consisted of bringing the thumb and a finger together

at a specific sequence. The research examined the " how " aspect of

memory in the participants' ability to perform the task quickly and

in the correct sequence. One of the groups was allowed to nap for an

hour and a half after learning the task while the other group stayed

awake.

The group that slept in the afternoon showed a distinct improvement

in their task performance by that evening, as opposed to the group

that stayed awake, which did not exhibit any improvement. Following

an entire night's sleep, both groups exhibited the same skill

level. " This part of the research showed that a daytime nap speeds

up performance improvement in the brain. After a night's sleep the

two groups were at the same level, but the group that slept in the

afternoon improved much faster than the group that stayed awake, "

stressed Prof. Karni.

A second experiment showed that another aspect of memory

consolidation is accelerated by sleep. It was previously shown that

during the 6-8 hours after completing an effective practice session,

the neural process of " how " memory consolidation is susceptible to

interference, such that if, for example, one learns or performs a

second, different task, one's brain will not be able to successfully

remember the first trained task.

A third group of participants in the University of Haifa study

learned a different thumb-to-finger movement sequence two hours

after practicing the first task. As the second task was introduced

at the beginning of the 6-8 hour period during which the brain

consolidates memories, the second task disturbed the memory

consolidation process and this group did not show any improvement in

their ability to perform the task, neither in the evening of that

day nor on the following morning. However, when a fourth group of

participants was allowed a 90 minute nap between learning the first

set of movements and the second, they did not show much improvement

in the evening, but on the following morning these participants

showed a marked improvement of their performance, as if there had

been no interference at all.

" This part of the study demonstrated, for the first time, that

daytime sleep can shorten the time " how to " memory becomes immune to

interference and forgetting. Instead of 6-8 hours, the brain

consolidated the memory during the 90 minute nap, " explains Prof.

Karni who added that while this study demonstrates that the process

of memory consolidation is accelerated during daytime sleep, it is

still not clear which mechanisms sleep accelerates in the process.

The elucidation of these mechanisms, say the researchers, could

enable the development of methods to accelerate memory consolidation

in adults and to create stable memories in a short time. Until then,

if you need to memorize something quickly or if your schedule is

filled with different activities which require learning " how " to do

things, it is worth finding the time for an afternoon nap.