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Science Catching Up With Jet-Lag
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NEW YORK (Reuters) -- It may be possible for travelers who fly across
several time zones to beat jet-lag.
A report in The Lancet looks at how the hormone melatonin and other
preventive measures can help the body's internal clock catch up with the new
time zone.
The collection of symptoms that characterize jet-lag include fatigue,
headache, irritability, loss of concentration, stomach and bowel upset, and
inability to sleep at the new night-time.
"Individuals experience some or all of the symptoms of jet-lag to differing
extents," says Dr. Jim Waterhouse and his colleagues at Liverpool John
Moores University in Liverpool, England. "Generally, symptoms are worse the
older the traveler and the more time zones crossed; eastward travel is
associated with worse symptoms (than) westward."
The researchers note that symptoms of jet-lag do not arise after
long-distance travel to the north or south since no time-zones are crossed.
The problem occurs because the body's internal clock deep in the brain
cannot react quickly to a change in the external day/night cycle.
For jet-lag prevention and to ease symptoms, the researchers recommend the
following:
* Arrange flights well in advance of an important event;
* When crossing multiple time-zones, schedule a stop-over for a day or
two;
* Drink lots of fluids to compensate for the dry air aboard jetliners,
but avoid alcohol and coffee since both increase water loss;
* Take naps when feeling most tired, including after a work session and
before an important task;
* Avoid exposure to bright light that produces a shift in the body clock
opposite to what is desired. Bright light in the morning advances the
body clock, and in the evening delays it. Staying indoors or wearing
dark glasses can help.
How the hormone melatonin acts to fight jet-lag remains unclear. The
Liverpool researchers say melatonin is "believed to be the best
pharmacological cure for jet-lag available, although the possibility for
unknown side effects requires further study." Melatonin is produced in the
pineal gland at the base of the brain.
Waterhouse and his colleagues point out that because melatonin lowers body
temperature (possibly a precursor signal to sleep), it should be taken at
about 8 p.m. in the new time zone.
The researchers note that the hormone is not licensed in Europe or
Australia, nor are U.S. doctors permitted to prescribe it. They caution that
the availability of melatonin through health food retailers in the U.S.
means there are no medical checks on how much is taken or on the effects of
long-term usage.
SOURCE: The Lancet (1997;350:1011-1016)
1997 Reuters Health eLine
http://www.medscape.com/reuters/tue/t1201-2f.html
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