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(The first of three parts)
AT 6 am,
the hospital’s bright hallway lights flicker on,
signaling the start of a new day. Doctors in crisp
business clothes appear on their early-morning rounds,
and the clang of breakfast carts will soon echo through
the unit. For registered nurse Liberty Bunag, however,
it’s finally time to go home and sleep. She began her
shift 12 hours ago with an extra-large coffee and since
has consumed a liter of caffeinated soda, more coffee
and lots of rice, her personal energy food. Sometimes
she and the other nurses on the orthopedic ward of White
Memorial Medical Center in Los Angeles practice foreign
languages to stay alert, squelching the yawns and
drowsiness—the body’s way of protesting this nocturnal
activity.
Bunag’s
head throbs as she walks to her car. “When I get home,”
says the 26-year-old from Torrance, “my body is tired
and my mind is exhausted.”
In a
24/7 world, such fatigue passes for normal. Twenty
percent of American workers are night-shift workers, and
the number is growing by about 3 percent per year,
according to the Bureau of Labor Statistics. While the
rest of society sleeps, police officers, security
guards, truck drivers, office-cleaning crews, hotel-desk
clerks, nurses, pilots and many others keep patients
alive, streets safe and packages moving. But at a price.
These
workers—and people with more conventionally
sleep-deprived lifestyles—are known to be at higher risk
for accidents, sleep disorders and psychological stress
due to daytime demands, such as family and other
obligations, that interfere with sleeping. Now
scientific evidence suggests their disrupted circadian
rhythms may also cause a kind of biological revolt,
raising their likelihood of obesity, cancer,
reproductive-health problems, mental illness and
gastrointestinal disorders.
The
evidence for an increased cancer risk is so compelling
that, in December, the
International Agency for Research on Cancer, a unit
of the World Health Organization, declared that shift
work is “probably carcinogenic to humans.”
Researchers are beginning to understand why. Among the
most significant—and startling—reasons: As much as 15
percent of human genes function on a schedule, with
highly regulated, oscillating patterns of activity.
These
clocklike genes are common features of most cells and
can be found in every major organ in the body. They, in
turn, affect the schedule of scores of biological
functions, from metabolism to cell division to cognitive
processes.
“Less
than 10 years ago, it was thought that sleep was for the
brain and not for the rest of the body, so lack of sleep
would make you tired, moody and more likely to have
accidents,” says sleep researcher Eve Van Cauter, a
professor of medicine at the University of Chicago. “But
sleep deprivation may be bad for the body, too,
representing a risk for a variety of abnormal
conditions.”
Evolution supports that theory. Life on Earth began with
single-cell organisms that depended on sunlight for
converting energy to food. “Life has been adapting to a
light-dark cycle since the beginning of the planet,”
says Paolo Sassone-Corsi, chairman of the department of
pharmacology at UC Irvine.
But
modern humans wrongly think they can override their
natural sleep patterns with impunity, says Dr. Charles
Czeisler, director of the division of sleep medicine at
Harvard Medical School.
“It’s a myth that we alone, among all animals, have the
power to sleep when we want,” he says.
(Next week: Grim health results of a sleep-deprived
lifestyle.) |
