New research show that power nap of just 45 minutes boosts memory

Professor Axel Mecklinger of Saarland University found that a nap 'produces a five-fold improvement in information retrieval from memory.'

A short doze helps you to retain information you have learned and 'significantly' improves recall, scientists say,meaning naps really could help students revising for exams.

When they were then retested, those who had slept remembered more word pairs, the journal Neurobiology of Learning and Memory reports.

The scientists, from Saarland University in Germany, said that during sleep, bursts of brain activity known as sleep spindles play an important role in consolidating newly learned information.

'The memory performance of the participants who had a power nap was just as good as it was before sleeping, that is, immediately after completing the learning phase.

'Strictly speaking, memory performance did not improve in the nap group relative to the levels measured immediately after the learning phase, but they did remain constant.'

'A short nap at the office or in school is enough to significantly improve learning success. Wherever people are in a learning environment, we should think seriously about the positive effects of sleep,' says Axel Mecklinger.

'Enhancing information recall through sleeping doesn't require us to stuff bulky tomes under our pillow.

'A concentrated period of learning followed by a short relaxing sleep is all that's needed.'

Participants in the study learned 90 single words and 120 unconnected word pairs such as 'milk taxi'.