Sleep deprived brain not to be trusted

Scientists are warning that sleep derivation affects how well the brain performs - they say any reliance on a sleep deprived-brain to perform well is potentially dangerous.

In a study by researchers from Singapore it has been revealed that even after sleep deprivation, people have periods of near normal brain function in which they can finish tasks quickly.

However the danger lies in the mixture with periods of slow response, because this is when severe drops in visual processing and attention occur.

The study, by a team at the Duke-NUS Graduate Medical School Singapore has found that the periods of apparently normal functioning could give a misleading appearance of competency and have implications for shift-workers and others coping with night work.

Lead researcher Professor Michael Chee says periods of apparently normal functioning could give a false sense of competency and security which could have dire consequences because of the sleep-deprived brain's inconsistency.

The researchers found that a sleep-deprived brain can normally process simple visuals such as flashing checkerboards but when it comes to "higher visual areas" which are responsible for making sense of what we see, it did not function so well.

Professor Chee says this is where the peril of sleep deprivation lies.

The researchers reached this conclusion by using magnetic resonance imaging (MRI) to measure blood flow in the brain as a way to gauge activity.

The study participants who were either kept awake all night or allowed a good night's sleep, were asked to identify letters flashing briefly in front of them which were 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.

It was seen that during slow responses, sleep-deprived volunteers had dramatic decreases in their higher visual cortex activity and their frontal and parietal 'control regions' were less able to make their usual corrections.

This meant that they failed to kick in for these lapses in attention and brief failures were also in the control regions during the rare lapses that volunteers had after a normal night's sleep.

The scientists say the failures in visual processing were specific only to lapses that occurred during sleep deprivation.

They say they found that the brain of a sleep-deprived individual works normally sometimes, but intermittently suffers from something similar to power failure.

Sleep experts say the study confirms a long held suspicion and highlights the importance of preventing sleep deprivation in people who are doing critical tasks, such as night driving.

It is a cause for concern because although sleep deprivation harms decision making and may increase on-the-job errors, sleep-deprived workers may not know they are impaired.

Experts say sleep deprivation is believed to have contributed to a number of the world's major disasters and the evidence suggests that sleep deprived people could perform simple tasks, and interesting complex tasks well but was a problem in performing relatively complicated, but essentially boring tasks, such as driving.

The study is published in the current issue of The Journal of Neuroscience.