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Enough sleep improves memory
Flinders University   
Thursday, 24 July 2008

Grumpiness and lethargy are well recognised behaviours in schoolkids with insufficient sleep, but a new study at Flinders University shows that lack of sleep impairs children’s ‘working memories’, negatively affecting their academic ability and ultimately dragging down their marks and grades.

Flinders psychologist and sleep researcher Dr Michael Gradisar led a study of adolescent schoolchildren that shows the performance of complex tasks that require information to be retained while other information is processed are affected by levels of sleep.

Previously, investigations of links between poor sleep and working memory performance based on simple memory tasks suggested that performance was unaffected.

“Previous studies suggested that despite getting inadequate sleep, kids could tolerate it and still function,” Dr Gradisar told Flinders Journal.

“But we have found that when challenged with a more complex task, adolescents who have been having less than eight hours sleep begin to have trouble,” he said.

Dr Gradisar said adolescents who had insufficient sleep displayed an impaired ability to encode, store and retrieve information. In the school setting, these difficulties affect tasks such as dictation, which requires information to be retained while writing, and multi-step problems in mathematics.

“Kids learn a whole range of different abilities at school, and we have shown that some of these abilities are susceptible to sleep loss,” Dr Gradisar said.

“This has implications for their learning and their overall grades.”

The study, published in the journal Sleep and Biological Rhythms, found eight to nine hours sleep appeared to be optimal: the researchers observed a plateau effect, with no further improvement in performance associated with more than nine hours. Further research aims to test the effect of shortened sleep on performance in areas such as abstract thinking and novel problem-solving.

Following the small-scale studies, PhD student Michelle Short has embarked on a larger project to determine the prevalence of inadequate sleep among school students in Years 9 to 11. As well as completing a questionnaire, participants keep a sleep journal for a week, and their activity levels are logged by a wrist monitor.

“The early indications are that the incidence of problematic sleep is much higher than we anticipated,” Dr Gradisar said.

Early results show some adolescents take almost an hour to fall asleep, contributing to bad sleep patterns.

To address these problems, Dr Gradisar and his team have set up the Child and Adolescent Sleep Clinic where they correct sleep problems in school-aged children. Treatments are also offered for infants and toddlers.


Editor's Note: Original news release can be found here.
 

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