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Mind gains

How can you help children remember what they've learnt at school? Let them sleep and their brains will take care of it all, says Susan Greenfield

As exam time looms, it can be hard for teachers and parents to persuade their charges to get to bed at a reasonable hour. They've got too much revision to do, they say.

Perhaps it would be easier if they knew how vital for their academic performance it is to get enough sleep. Science is only just beginning to uncover the extent of the role it plays in maintaining a healthy mind.

It is certainly crucial to improving and embedding memory. If children in your class are constantly tired, you can take a pretty good guess that their ability to form new memories and recall old memories won't be up to scratch.

People who are unfamiliar with the workings of the brain may have heard of a structure called the hippocampus, which shot to fame in a well-known study with London taxi drivers.

The hippocampus is situated deep in the brain and plays an important role in encoding spatial memories. The study showed that as taxi drivers learnt a mental map of every street in London (The Knowledge) the size of their hippocampi increased - a fact not lost on London taxi drivers. Sleep helps to lay down those new spatial memories, as it is during sleep that new hippocampal cells tend to grow.

Although the hippocampus acts as a store for spatial memories, the long-term encoding of most memories occurs in the outer layers of the brain - the cortex. The hippocampus is thought to act as kind of memory junction box, linking and drawing together different aspects of memory from around the brain.

Sleep has another crucial role in this function: during sleep, low-frequency rhythms enable the hippocampus to synchronise with regions of the cortex and so consolidate the transfer of memories from one region to the other. Without sleep, those long-term memories just wouldn't last.

The role of sleep in embedding previous experience was shown in an elegant set of experiments by Pierre Maquet and colleagues at the Universite de Liege in Belgium. Using imaging and regional blood flow measurements, they showed that during certain stages of sleep the brain reactivated networks that had been used the previous day to perform a reaction-time task.

While participants in the study slumbered peacefully, their brains were busy retracing the networks that had been used while awake. Without any further training, the sleep significantly improved their performance on the task, suggesting learning had been reinforced from the previous day.

So sleep is vital not just to help you learn effectively during the day, but also to enable your brain to reinforce your learning during the night.

Understanding the effects of sleep on the brain can make teachers more self-confident in their dealings with pupils and parents. Rather than simply expressing regret that pupils look tired, you can explain exactly why they need sleep and give them advice on how to get more of it.

That was certainly what we found during a recent pilot project with Advanced Skills Teachers in Gloucestershire at the Institute for the Future of the Mind.

Liz Pratten, a primary teacher from Glenfall Community Primary School in Cheltenham, organised an after-school session for parents to discuss the role and importance of sleep in learning, including how to ensure their children were not disrupting sleep patterns with late-night television watching and computer use. Her Year 5s even tried practising their times tables before they went to sleep. Maybe counting sheep does have some benefits.

What applies to pupils applies to teachers, too. Running over tomorrow's lesson plan in your pyjamas might not be the most enthralling prospect before you go to bed. Nevertheless, it might be a handy way of letting your brain do the work while you are taking that well-earned rest.

Baroness Susan Greenfield is Professor of Pharmacology at the University of Oxford and director of the Royal Institution of Great Britain


Maquet, P et al (2000) "Experience-dependent changes in cerebral activation during human REM sleep" Nature Neuroscience 3(8) p831

Alan Baddeley (2004) Your Memory: A User's Guide, Firefly

Overview of the "Science of Learning" project at the Institute for the Future of the Mind:

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