Sleep-deprived brains are inattentive: study

May 21st, 2008 - 4:16 pm ICT by admin  

New York, May 21 (IANS) Brain activity differs significantly in sleep-deprived and well-rested people, according to a new study that uses the latest imaging techniques. The study, by Singapore-based researchers, shows that the sleep-deprived experience periods of near-normal brain function - interspersed with severe drops in attention.

“The main finding is that the brain of the sleep-deprived individual is working normally sometimes, but intermittently suffers from something akin to power failure,” said Clifford Saper of Harvard University, an expert unaffiliated with the study.

Findings of the study have been published in the latest issue of The Journal of Neuroscience.

The research team, led by Michael Chee, used functional magnetic resonance imaging (fMRI) to measure brain blood flow in people who were either kept awake all night or allowed a good night’s sleep. Researchers tested the same participants in both conditions.

During imaging, participants did a task that required visual attention. Researchers showed them large letters composed of many smaller letters. Participants were asked to identify either the large or small letters and to indicate their responses by pushing a button.

Well-rested and sleep-deprived volunteers showed a range of reaction times. Those participants with the fastest responses, both in sleep-deprived and well-rested conditions, showed similar patterns of brain activity.

However, well-rested and sleep-deprived participants with the slowest responses - also called attentional lapses - showed different patterns of brain activity.

Previous research showed that attentional lapses normally induce activity in frontal and parietal regions of the brain, command centres that may compensate for lost focus by increasing attention.

However, during attentional lapses, Chee and colleagues found reduced activity in these brain command centres in sleep-deprived compared to well-rested volunteers. This finding suggests that sleep deprivation reduces the brain’s ability to compensate for lost focus.

Sleep-deprived people also showed reduced activity in brain regions involved in visual processing during attentional lapses.

Because the brain becomes less responsive to sensory stimuli during sleep, reduced activity in these regions suggests that, during attentional lapses, the sleep-deprived brain enters a sleep-like state.

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