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Thursday, 10 February, 2000, 00:50 GMT
Brain 'battles sleep deprivation'
Brain scans showed increased activity
The brain takes steps to counter the effect of sleep deprivation, research shows.

But the ability of the brain to maintain something resembling normality following a lack of sleep varies between different tasks.

Researchers at the University of California found that parts of the brain were activated when volunteers were given simple verbal learning tasks to do after 35 hours without sleep, but their ability to do mathematical sums was badly impaired.

Sleep deprivation does have detrimental effects, which we sometimes forget as we push workers, students and others to perform even when they are functioning with a lack of sleep

Professor J Christian Gillin
Scanning their brains using functional magnetic resonance imaging, the scientists found that a region involved in language processing - the temporal lobe, part of the prefrontal cortex - was activated during verbal learning in rested patients.

It was not active in those who had been sleep deprived. Instead, a region called the parietal lobes, also part of the prefrontal cortex and usually associated with arithmetic performance - was brought into play.

But, when arithmetic tasks were performed after being denied sleep, there was no equivalent activation of areas of the brain.

The team, led by professor of psychiatry J Christian Gillin, was surprised at the increased activity in direct correlation to the person's sense of sleepiness.

"Only in recent years have we begun to realise the prevalence and severity of sleep deprivation in our population," said Professor Gillin.

"It is important to remember that sleep deprivation does have detrimental effects, which we sometimes forget as we push workers, students and others to perform even when they are functioning with a lack of sleep."

Diminished ability

The brain is dynamic in its efforts to function when deprived of sleep, though the consequence for the subject is diminished ability to perform certain tasks, he says in the journal Nature.

He explained the difference in reaction to verbal and arithmetic tasks, saying: "The parietal lobes are the system primarily associated with arithmetic performance when subjects are well rested, so when it becomes less responsive with sleeplessness, there is not a brain system available to come online to compensate for the negative effects of sleep deprivation."

Professor Neil Douglas, director of the Scottish National Sleep Centre, said the effect of sleep deprivation did depend on the task being attempted by the sleep deprived person. "It is very task specific," he said.

The findings of Professor Gillin's research could help counter sleep deprivation in the future, he said.

"The effect of higher brain function is known, but if we are going to eventually think of ways of getting round that, this is a piece of the jigsaw towards working out the broader basis for a possible remedy."

See also:

23 Mar 99 | Health
Sleep deprivation dangers
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