Lack of sleep 'renders brain erratic'
Pastor Dale Morgan
Lack of sleep 'renders brain erratic'*
BBC - Scientists have shown relying on the sleep-deprived brain to
perform well is potentially fraught with danger.
They found that even after sleep deprivation, people have periods of
near normal brain function in which they can finish tasks quickly.
However, this is mixed with periods of slow response and severe drops in
visual processing and attention.
The study, by Duke University and the National University of Singapore,
appears in the Journal of Neuroscience.
The periods of apparently normal functioning could give a false sense of
competency
Professor Michael Chee
The researchers said the findings had implications for people who have
to struggle through night work, from long distance lorry drivers to
on-call doctors.
Lead researcher Professor Michael Chee said: "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."
The researchers found that a sleep-deprived brain can normally process
simple visuals, like flashing checkerboards.
However, the "higher visual areas" - those responsible for making sense
of what we see - didn't function well.
As Professor Chee put it: "Herein lies the peril of sleep deprivation."
The researchers used a technique called magnetic resonance imaging to
measure blood flow in the brain as a way to gauge activity.
Flashing letters
Study subjects, 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.
They saw either a large H or S, and each was made up of smaller Hs or Ss.
Sleep deprivation is believed to have contributed to major disasters
ranging from the major oil spillage of the Exxon Valdez to the nuclear
meltdowns of Three Mile Island and Chernobyl-Dr Andrew Cummin-Imperial
College Healthcare Sleep Centre
Sometimes the large letter matched the smaller letters; sometimes they
didn't.
Scientists asked the volunteers to identify either the smaller or the
larger letters by pushing one of two buttons.
During slow responses, sleep-deprived volunteers had dramatic decreases
in their higher visual cortex activity.
At the same time their frontal and parietal 'control regions' were less
able to make their usual corrections - in effect they failed to kick in
for these lapses in attention.
Scientists also could see brief failures in the control regions during
the rare lapses that volunteers had after a normal night's sleep.
However, the failures in visual processing were specific only to lapses
that occurred during sleep deprivation.
Dr Clifford Saper, of Harvard University, said: "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."
Major disasters
Dr Neil Stanley, a sleep expert from Norfolk and Norwich University
Hospital, said the study appeared to prove what scientists had long
suspected.
"It is worrying for night workers as it suggests they can potentially
convince themselves they are performing OK but they are liable to lapses."
Dr Stanley said there was evidence to suggest that sleep-deprived people
could perform simple tasks, and interesting complex tasks well.
The problem came in performing relatively complicated, but essentially
boring tasks, such as driving.
Dr Andrew Cummin, of the Imperial College Healthcare Sleep Centre, said:
"Sleep deprivation is believed to have contributed to major disasters
ranging from the major oil spillage of the Exxon Valdez to the nuclear
meltdowns of Three Mile Island and Chernobyl.
"But whether anything much can be done about this is doubtful. For the
time being the only solution we have is to make sure we all get enough
sleep."