IF YOU are trying to commit something to memory, take a nap. Even a short daytime snooze could help you learn.

A good night's sleep is known to improve people's ability to learn actions such as mirror writing. REM sleep, when most dreaming occurs, is thought to be particularly important.

The role of sleep in factual learning has been less clear. Now Matthew Tucker at The City University of New York and his colleagues have shown that even a nap with no REM sleep can help.

Volunteers were told to memorise pairs of words (a test of factual learning) and to practise tracing images in a mirror (action learning). When they were tested straight afterwards and 6 hours later, those who had been allowed a nap of up to 1 hour before the re-test scored 15 per cent better in the factual test than the non-nappers, but no better in the action test (Neurobiology of Learning and Memory, vol 86, p 241).

"Traditionally, time devoted to daytime napping has been considered counterproductive," the researchers say. It now seems sleep is "an important mechanism for memory formation".

From issue 2570 of New Scientist magazine, 23 September 2006, page 17