Power Nap

In a test of their ability to remember facts, the volunteers were asked to memorise pairs of words, such as 'clock' and 'hands'. Their ability to learn an action was also tested, with the men and women trying to accurately trace the mirror image of a complex pattern.

Then, half the group were taken to a sound- proof chamber. Although they were allowed to nap for up to an hour, the average time spent asleep was 47 minutes.While they snoozed, the others relaxed by reading magazines and watching films. Six hours after the start of the experiment, both sets of volunteers were re-tested on the memory and mirror games.

While both groups performed equally well on the mirror-image test, those who had the siesta did better on the memory test than those who had stayed awake all afternoon.In fact, the nappers remembered 15 per cent more word pairs, this week's New Scientist reports.The researchers believe that non-REM sleep - the dreamless period that accounts for the first 90 minutes to two hours after we fall asleep - may play a crucial role in factual learning.

During this time, the conditions needed for storing facts for easy retrieval are just right. However, if you sleep longer, and go into REM sleep, in which dreaming occurs,the effects may be cancelled out. They caution, however, that while a nap may help with recall later the same day, it is not clear the memory-boosting effect is long-lasting.

Famous siesta-takers include Sir Winston Churchill, who swore by a mid-afternoon snooze followed by a bath, and even stuck to his routine during the Second World War.Margaret Thatcher liked to prepare herself for Prime Minister's Questions by taking a 20-minute afternoon power nap.

Sleeping on the job can improve your work | News | This is London

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