2008-02-21 12:08:11
Even the shortest of catnaps may be enough to improve performance in memory
tests, say German scientists.
Just six minutes "shut-eye" for volunteers was followed by significantly better
recall of words, New Scientist magazine reported.
"Ultra-short" sleep could launch memory processing in the brain, they
suggested.
One UK researcher disagreed, saying that longer sleep was needed to have an
impact on memory.
This demonstrates for the first time that an ultra-brief sleep episode provides
an effective memory enhancement
University of Dusseldorf researchers
Dozens of studies have probed the relationship between sleep and memory, with
clear evidence that body's natural sleep-wake cycle plays an important role.
The team from the University of Dusseldorf wanted to see just how short a sleep
could have any discernable impact.
They used a group of students who were asked to remember a set of words, then
given an hour's break before testing.
During that hour, some of the students were allowed to sleep for approximately
six minutes, while the rest were kept awake.
Remarkably, on waking, the napping students performed better in the memory
test.
Some theories suggests that the processing of memories takes place in deep
sleep, a phase which does not normally start until at least 20 minutes after
falling asleep.
Six minute warning
However, the team, led by Dr Olaf Lahl, said that it was possible that the
moment of falling asleep triggered a process in the brain that continued
regardless of how long the person actually stayed awake.
"To our knowledge, this demonstrates for the first time that an ultra-brief
sleep episode provides an effective memory enhancement," he wrote.
Professor Jim Horne, from the Sleep Research Centre at Loughborough University,
said that while the study was "interesting", he was yet to be convinced that
the effect was purely one of memory enhancement.
"The idea that memory could be enhanced in just six minutes is a quite unique
finding and one has to be rather cautious about it.
"There is quite a bit of evidence that memory processing probably takes place
more than six minutes into sleep."