October 2, 201712:31 PM ET
Research that helped
discover the clocks running in every cell in our bodies earned three scientists
a Nobel Prize in medicine on Monday.
"With exquisite precision, our inner clock adapts our
physiology to the dramatically different phases of the day," the Nobel
Prize committee wrote of
the work of Jeffrey C. Hall, Michael Rosbash and Michael W. Young. "The
clock regulates critical functions such as behavior, hormone levels, sleep,
body temperature and metabolism."
We humans are
time-keeping machines. And it seems we need regular sleeping and eating
schedules to keep all of our clocks in sync.
Studies show that if
we mess with the body's natural sleep-wake cycle — say, by working an overnight
shift, taking a trans-Aatlantic flight or staying up all night with a new baby
or puppy — we pay the price.
Our blood pressure
goes up, hunger hormones get thrown off and blood sugar control goes south.
We can all recover from an occasional all-nighter, an episode
of jet lag or
short-term disruptions.
But over time, if
living against the clock becomes a way of life, this may set the stage for
weight gain and metabolic diseases such as Type 2 diabetes.
"What happens is that you get a total de-synchronization of
the clocks within us," explains Fred Turek, a
circadian scientist at Northwestern University. "Which may be underlying
the chronic diseases we face in our society today."
So consider what
happens, for instance, if we eat late or in the middle of the night. The master
clock — which is set by the light-dark cycle — is cuing all other clocks in the
body that it's night. Time to rest.
"The clock in the
brain is sending signals saying: Do not eat, do not eat!" says Turek.
But when we override
this signal and eat anyway, the clock in the pancreas, for instance, has to
start releasing insulin to deal with the meal. And, research suggests, this
late-night munching may start to reset the clock in the organ. The result?
Competing time cues.
"The pancreas is
listening to signals related to food intake. But that's out of sync with what
the brain is telling it to do," says Turek. "So if we're sending
signals to those organs at the wrong time of day — such as eating at the wrong
time of day — [we're] upsetting the balance."
And there's
accumulating evidence that we may be more sensitive to these timing cues than
scientists ever imagined.
Consider, for instance, the results of a weight-loss study that
we reported on,
which was published in
2013 in the International Journal of Obesity.
Researchers found that the timing of meals can influence how much weight people
lose.
"The finding that we had was that people who ate their main
meal earlier in the day were much more successful at losing weight," says
study author Frank Scheer,
a Harvard neuroscientist who directs the Medical Chronobiology
Program at Brigham and Women's Hospital.
In fact, early eaters lost 25 percent more weight than later
eaters — "a surprisingly large difference," Scheer says. Another study found
that eating a big breakfast was more conducive to weight loss, compared with a
big dinner — adding to the evidence that the timing of meals is important.
Beyond weight
management, there's evidence that the clocks in our bodies — and the timing of
our sleeping, eating and activities — play multiple roles in helping us
maintain good health. And different systems in the body are programmed to do
different tasks at different times.
For instance, doctors
have long known that the time of day you take a drug can influence its potency.
"If you take a drug at one time of day, it might be much more toxic than
another time of day," Turek says. Part of this effect could be that the
liver is better at detoxifying at certain times of day.
Turek says his hope is
that, down the road, circadian science will be integrated into the practice of
medicine.
"We'd like to be
in a position where we'd be able to monitor hundreds of different rhythms in
your body and see if they're out of sync — and then try to normalize
them," Turek says.
Whether — or how
quickly — this may happen is hard to say. But what's clear is that the study of
the biology of time is exploding.
"What we're doing
now in medicine is what Einstein did for physics," says Turek. "He
brought time to physics. We're bringing time to biology."
The irony, of course,
is that this insight comes at a time when the demands of our 24/7 society mean
more and more of us are overriding our internal clocks.
A previous version of this story was published in 2015.
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