快猫短视频

GLOBETROTTING across several time zones on long-haul flights impairs memory
and reaction times by shrinking part of the brain. This might mean that airlines
should allow their crews at least 10 days to recover from jet lag before they
work on another long-haul flight, says the scientist who discovered the
effect.

Last year, a team led by Kwangwook Cho of the University of Bristol found
that airline crew who often travel across many time zones have high levels of
the stress hormone cortisol, as a result of jet lag disrupting their daily sleep
patterns. The long-distance flyers also had some cognitive defects, such as
impaired reaction times, although it was not clear whether this was
permanent.

High cortisol levels can alter the structure of the brain, and Cho suspected
this might be behind the cognitive defects. For instance, stressed Vietnam
combat veterans with high cortisol levels were found to have an unusually small
hippocampus, a key brain region for learning and memory.

To find out more, Cho looked at 20 female flight attendants who had worked
for international airlines for 5 years or more and frequently worked on flights
crossing at least seven time zones. Half were employed by companies that
routinely gave them less than 5 days between take-offs to recover from each
long-haul flight. The other half had 14 days to recover, taking only short
flights during that time.

Cho used brain scans to measure the size of the volunteers鈥� temporal
lobes鈥攂rain regions that include the hippocampus. 鈥淭hese are crucially
involved in learning and memory,鈥� says Cho. The right and left temporal lobes
were the same size in women given around two weeks to recover from jet lag. But
the right temporal lobe was much smaller than the left lobe in women given a
short recovery time. The higher the cortisol levels in their saliva, the more
dramatic was the size difference.

Cho also tested the women鈥檚 ability to memorise the position of a spot on a
screen and later recognise another spot in the same position. The women who had
little time to recover from jet lag gave more wrong answers and had slower
reaction times than women given at least two weeks to readjust.

A greater gap between long-haul flights would prevent cabin crew and frequent
flyers suffering such difficulties, says Cho. 鈥淚f they fly over six or seven
time zones, they should have at least 10 days鈥� recovery period,鈥� he says. He
plans to test whether the problem is worse for eastbound or westbound
flights.

鈥淐learly this is an interesting area of investigation,鈥� says Trevor Phillips,
the flight scheduling officer for the British Airline Pilots Association, based
at London鈥檚 Heathrow Airport. He says recovery from jet lag for pilots and other
crew is routinely cut short by more long-haul flights, with little respite
except during holidays.鈥漈he possibility that this activity, already acknowledged
as very tiring, is actually damaging the mental capacity of those exposed makes
daunting reading,鈥� he adds.