A good night's sleep 'could hold key to improved memory'

A GOOD night's sleep could be the key to a good memory and can help people imagine what will happen in the future, according to new research.

Sleep researchers have discovered people's capacity in word association tests is improved after a period of REM (rapid eye movement) sleep - which is when dreams are most vivid.

Scientists hope the latest research on sleep and memory will improve life for people with diseases such as Alzheimer's.

Dr Sara Mednick, of the University of California, said: "REM sleep is important for pulling together all the information we process daily and turning it into memories we can use later.

"This helps us to understand more about the benefits of sleep and to help people maximise their sleep schedules for optimal productivity and memory retrieval."

The researchers asked participants to find a word that associated multiple groups of three words - such as "heart", "cookie" and "sixteen" - which are all associated with the word "sweet".

They were tested once in the morning and again in the afternoon, after a nap with or without REM sleep. The REM sleep group showed a 40 per cent improvement in the afternoon over their morning scores.

Dr Mednick believes links are made between previously unassociated information during REM sleep because of changes that happen in neurotransmitters while people are dreaming.

People's memories may also help them imagine their future, according to researcher Daniel Schacter, a psychology professor at Harvard University in the United States.

Dr Schacter and his colleagues have been conducting brain imaging research that suggests that the ability to remember past events may be an important factor in people's ability to imagine things that have not happened yet and even simulate "future" events.

Studies show certain brain regions traditionally associated with memory, such as the medial temporal lobe, appear to be similarly activated when people imagine future experiences in brain imaging studies, according to Dr Schacter.

He said: "Memories of things that have already happened to us apparently support the formation in our minds of future events by taking and recombining stored information into an event we imagine will happen. "This can have far-reaching implications for how we think about memory and its function."

The medial temporal lobe, which includes the hippocampus, is the subject of further memory research by Dr Michela Gallagher, a neuroscientist at Johns Hopkins University, also in the US.

The primary risk for Alzheimer's disease is often preceded by a condition known as amnestic mild cognitive impairment (aMCI) in which people have greater memory loss than would be expected as they grow older.Dr Gallagher said: "These people may offer the best opportunity for intervention to treat symptoms and stem the tide of the disease."

Her research on memory loss in aged rats is providing clues about the condition of aMCI.

Dr Gallagher's study shows certain neurons in the hippocampus are excessively active in the brains of older rats with memory loss.

She said: "The changes in this neural network that are seen both in older animals and humans may shed light on a permissive condition in the ageing brain that confers risk for Alzheimer's disease and the special vulnerability of memory in this most common form of dementia. It is giving us new ideas about how to treat progressive memory loss in older adults."