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TIME: Almanac 1990
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1990 Time Magazine Compact Almanac, The (1991)(Time).iso
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060589
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06058900.003
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1990-09-17
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HEALTH, Page 66The Times of Your LifeAn underground study shows how internal clocks can go awry
Stefania Follini could be forgiven for losing track of time.
On Jan. 13 the 27-year-old Italian interior designer descended into
a cave near Carlsbad, N. Mex., where she was to live for more than
four months as part of an experiment aimed at examining how the
stresses of long-term isolation could affect space travel. Pioneer
Frontier Explorations, an Italian research foundation, had selected
Follini, one of 20 volunteers for the assignment, because she was
judged to have inner strength and stamina. For 131 days she dwelled
alone in a 20-ft. by 12-ft. Plexiglas module sealed 30 ft. under
the surface, without sunlight or any other way of measuring time.
Last week she emerged aboveground on schedule. But by her
calculations it was only mid-March.
During Follini's subterranean stay, her sense of time had
elongated. Her "day" extended to 25 hours, then to 48 hours. She
tended to sleep for 22 to 24 hours, then burst into activity for
up to 30 hours. She ate less frequently and lost 17 lbs. Her
menstrual period stopped. In short, her internal biological clocks
had gone out of whack.
The New Mexico experiment called attention to an emerging field
in science called chronobiology, the study of the body's innate,
rhythmic patterns. Today researchers realize that many human
characteristics, from basic physiological functions such as blood
pressure and body temperature to mental sharpness and moods, follow
such patterns. Some cycles are as brief as seconds; the heart's
permeability to certain chemical ions appears to shift back and
forth in less than a minute. Others are measured in months; some
people regularly fall into deep depressions in winter and cheer up
in summer.
The best-known rhythms are circadian, from the Latin, meaning
"about a day." The sleep-wake cycle is the most obvious, but the
body's production of hormones also fluctuates significantly over
24 hours. Says Charles Ehret, president of General Chronobionics,
a research and consulting company in Hinsdale, Ill.: "Chemically,
you are a very different person at noon than you are at night."
Controlling the daily cycles is a cluster of 10,000 nerve cells
-- altogether about the size of the head of a pin -- that are
located in the hypothalamus, a segment of the brain. Some
biological timepieces appear to take their cue from temperature or
barometric pressure, but many are synchronized with the cycle of
light and darkness caused by the rising and setting of the sun.
Experiments conducted in caves, like the one in New Mexico, and
others in special laboratories purposely remove all such cues. In
Follini's module the temperature was a constant 69 degrees F, and
the only illumination was artificial. The aim of such experiments
is to get the body to "free-run" and see what sort of patterns it
establishes on its own.
The conditions of Follini's underground life were extreme, but
people's biological clocks can also be disrupted by the demands of
everyday life. Jetting across time zones, working twelve-hour days
or irregular shifts and even sleeping late can disturb biological
rhythms and impair efficiency and judgment. Government officials
and business leaders are routinely advised to recover from jet lag
before starting negotiations.
Investigators analyzing the blowup of the Challenger shuttle
and the disasters at Three Mile Island and Chernobyl have found
that in each case, critical errors were made by people struggling
with unusual work schedules and lack of sleep. The two nuclear
plant accidents happened in the wee hours of the morning.
Similarly, most truck wrecks related to fatigue occur between 2
a.m. and 4 a.m. "Shift workers classically have to perform when
their brains are trying to put them to sleep," observes Dr. Charles
Czeisler of Boston's Brigham and Women's Hospital. "They are
fighting the internal clock." Many workers run on automatic pilot
at that time; they execute routine tasks but are unable to process
new information, like flashing red lights that signal danger.
More sensible work schedules could reduce such hazards. In a
recent eleven-month experiment in Philadelphia, police were put on
a revised rotation that meshed better with their innate clocks. The
number of days worked consecutively was cut, and the officers were
not moved from one shift to another as frequently. Police on the
new schedule had 40% fewer patrol-car accidents than before, and
their use of sleeping pills and alcohol dropped by half.
Chronobiology also has implications for medical treatment.
Diagnostic tests can be misinterpreted if doctors are not aware of
biological rhythms. For instance, patients may react more strongly
to allergy tests that are given in the evening than to the same
tests done in the morning. Last week Dr. William Hrushesky of
Albany Medical College reported that women who undergo mastectomies
during their menstrual period appear to have a higher risk of dying
from breast cancer within five years than women who are operated
on in the middle of their monthly cycle. Hrushesky speculates that
hormones produced during menstruation somehow have a negative
effect on the body's immune system.
In the most promising medical application, doctors are
beginning to time medication to match biological cycles. Some
experts believe the effectiveness of cancer treatments can be
boosted -- and the harmful complications of the often toxic drugs
lessened -- by taking advantage of daily rhythms in the immune
system and cell division. Painful bouts of rheumatoid arthritis
occur most frequently in the morning, when natural
anti-inflammatory agents are least active; aspirin affords the best
relief when taken the night before. On the other hand, the time to
take medication for osteoid arthritis is midday; joints become
inflamed with movement, and pain occurs later in the day.
Scientists are also exploring ways of resetting the body's
clocks. Among the possible methods: using exercise, changing diet,
or varying the amount of light or sleep. Even chemical intervention
is being considered. Says neurobiologist Fred Turek of Northwestern
University: "One of our goals is to find safe drugs that can speed
up your clock or slow it down." Such techniques offer the
possibility that one day, humans will be not just captives but
masters of biological time.