One Up for the Spanish “Siesta”




Neuroscience_Neurology.jpgGood news from the world of medicine for those caught snoozing after lunch at their desks — you can claim it was a deliberate memory enhancement strategy. New research from the University of Haifa’s Center for Brain and Behavior Research shows that a 90-minute day nap speeds up the process of long-term memory consolidation as well as improve learned performance.

The findings of Dr. Maria Korman, Professor Avi Karni and their team were published recently in the journal Nature Neuroscence, based on a study of two groups of volunteers who were given a task that involved bringing together their thumb and finger repeatedly in a sequence. One group was allowed to take a 90 minutes afternoon nap after learning the task while the other group stayed awake. The group which took the afternoon nap showed a distinct improvement in its performance, compared to the other. By comparison, sleeping at night produced the same skill levels in both groups, demonstrating the improvement was causally related to the daytime nap only.

In another crucial part of the experiment, the role of a “siesta” was investigated in learning two tasks in sequence, with a gap of a few hours. Normally, learning a new task shortly after another one produces ‘interference’, by which the first task is often forgotten due to the effects of the second, as the former task’s memory has not had a chance to become “consolidated.” However, in the above experiment, a 90-minute daytime nap after learning the first task in a sub-group of volunteers produced significantly less “interference,” indicating that a short period of nap dramatically improved long-term memory consolidation of the first task.

Although the exact mechanism by which a short period of nap accelerates the memory consolidation of the learning process is unknown, the relationship between sleep and memory consolidation has been the focus of scientific study for quite some time. Day napping might be a good strategy to utilize in work situations where learning is involved, but some cultures know that already.

In Spain and Latin America, the “siesta” has been a tradition for many centuries — shops and establishments close for several hours, and after a refreshing afternoon sleep, resume their afternoon and evening business, feeling invigorated. Some Japanese offices have napping rooms where mid-day lunch-time sleep can be taken, and the Washington Post reported on February 13, 2007 about studies in Greece that indicate that daytime napping reduces the risk of heart disease, something which has been a tradition there.

Reference

Korman M, Doyon J, Doljansky J, Carrier J, Dagan Y, Karni A. Daytime sleep condenses the time course of motor memory consolidation. Nat Neurosci. 2007 Sep;10(9):1085-6.

Sudip Ghosh, MD

Sudip Ghosh, MD, is a surgeon at the University of Manchester, UK and a medical writer.
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