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Hopping the Concorde in New York and heading
to Paris for lunch may sound glamorous, but making a habit
of this kind of trip may
take a toll on your brain.
The right
temporal lobe, a part of the brain involved in
memory, is smaller in airline crew members who cross multiple
time zones and have only 5 days of rest before crossing time
zones again.
The crew members were compared with workers
who crossed multiple time zones but had 14 days of recovery
-- generally working flights that did not cross time zones
in that time -- before taking another flight around the world.
The findings are based on magnetic resonance
imaging (MRI) data from 20 female flight attendants who spent
at least 5 years crossing multiple time zones and who logged
a similar number of hours in the sky.
What's more, the researchers observed
an association between reduced volume of the right temporal
lobe and high levels of the stress hormone cortisol in airline
crew members.
And when the women in the study were given
tests to check their reaction times, the
short-recovery crew performed worse, taking an
average of 823 milliseconds to respond versus 741 milliseconds
for the long-recovery crew.
A previous study by the investigators
found that airline workers subjected to repeated jet lag had
higher levels of cortisol, as well as impaired memory.
Adjusting to different time zones can
disrupt the circadian rhythm -- the internal clock that regulates
when we sleep -- causing the groggy feeling known as jet lag.
The findings of the present study suggest
that jet lag recovery period
may be a potential way to eliminate the temporal lobe atrophy
associated with repeated jet lag.
Past studies of people with depression
or post-traumatic stress disorder have shown that high levels
of cortisol are associated with a reduction in temporal lobe
volume, as well as memory impairment.
Nature Neuroscience
May 2001;4:567-568
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