May 20, 2008

Sleep-Deprived Brains Show Lapse in Visual Processing

TUESDAY, May 20 (HealthDay News) -- Sleep deprivation can affect your ability to make sense of what you see, a study by neuroscience researchers at the Duke-NUS Graduate Medical School in Singapore shows.

Using MRI to measure blood flow in the brains of volunteers, the researchers found that even after sleep deprivation, participants had periods of near-normal brain function in which they were able to complete tasks quickly. However, periods of slow response and severe declines in visual processing were mixed in with these periods of normalcy.

"Interestingly, the team found that a sleep-deprived brain can normally process simple visuals, like flashing checkerboards. But the 'higher visual areas' -- those that are responsible for making sense of what we see -- didn't function well. Herein lies the peril of sleep deprivation," study author Dr. Michael Chee, a professor of the neurobehavioral disorders program at Duke-NUS, said in a prepared statement.

During these slow visual responses, the volunteers showed significant reductions in their higher visual cortex activity. At the same time, their frontal and parietal "control regions" were less able to make their usual connections.

The mixture of sleep deprivation-related cognitive lapses and near normalcy demonstrate the competing effects of trying to remain awake while the brain is trying to power down for sleep, when it ordinarily becomes less responsive to sensory stimuli, Chee said.

The study, published in the May 21 issue of the Journal of Neuroscience, has implications for the many people who work night shifts.

"The periods of apparently normal functioning could give a false sense of competency and security, when in fact, the brain's inconsistency could have dire consequences," Chee said.

"The study task appeared simple, but as we showed in previous work, you can't effectively memorize or process what you see if your brain isn't capturing that information," Chee noted. "The next step in our work is to see what we might do to improve things, besides just offering coffee, now that we have a better idea of where the weak links in the system are."

More information

The National Sleep Foundation has more about shift work and sleep.

-- Robert Preidt
SOURCE: Duke University, news release, May 20, 2008
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