A Time for Everything—Your Body’s Internal Clock

We live by the clock. Stop and think
about all the clocks that make our lives
tick, from the alarm clock that gets us
up in the morning to the thermostat
that warms our homes and the internal
clocks that run our cell phones and
computers. Every little gadget, device,
and smart appliance, along with the car
we drive, literally depends on internal
clocks. Our 24/7 world—from work to
pleasure—is governed by timekeepers.

Now scientists are discovering that
we’re not the only ones run by clocks.
The whole living world has built-in
clocks to keep its systems on schedule,
from humans and animals to plants
and single cells. Even at the chromosome
level, genes are turned off and on
by sophisticated clocks.

This dependence on the 24-hour
cycle of day and night should not surprise
us. Genesis’ account of creation
emphasizes that this cycle began on
day one, even before God created the
sun and planets. “And God said, ‘Let
there be light,’ and there was light.
And . . . God separated the light from
the darkness. God called the light
Day, and the darkness he called Night.
And there was evening and there was
morning, the first day” (Genesis 1:3–5).

The Lord waited until the fourth
day to place the celestial timekeepers
in the heavens “to divide the day from
the night; and let them be for signs and
seasons, and for days and years” (Genesis 1:14). At first glance, that sounds
odd. Why wait?

God shows that he was acting in
a deliberate order. He created not
just things but an amazing interconnected
system, where everything in
the universe would function interdependently.
And we’re just beginning to
understand how much God designed
life to run on the daily cycle of energizing
light and darkness.

The Rhythm of Life

Since ancient times, human beings have recognized that
our lives sync with this cycle, as we grow tired or hungry at
predictable times. But it wasn’t until a few decades ago that
scientists began exploring how our body’s systems are specifically
designed at a molecular level to interface with the
cycle of light and dark.

This special system is called a circadian rhythm or clock. (The
word circadian comes from the Latin circa, meaning “around”
as in a circular cycle, and the Latin word for “day,” diem.)

Increasing interest in this clock in the 1960s opened a
whole new field of biology known as chronobiology (the timing
of biological activity). This field of research continues
to revolutionize how we understand all of life and human
health. Medicines for common conditions like diabetes
and weight loss are profoundly affected by the time of day
they’re taken. In recognition of major research advances in
this field, the 2017 Nobel Prize in Physiology or Medicine
(yes, that’s its official name) was awarded to three scientists
who discovered “the molecular mechanisms controlling the
circadian rhythm.”

We now know that nearly every living thing on the planet,
including plants, animals, fungi, and even single-celled
photosynthetic bacteria, has this amazing ability to track
the course of the day-night cycle—with an accuracy down
to minutes. Life on earth could not exist without this ability
to adjust its processes and systems with the day-night cycle.
It governs when cells grow, metabolize, reproduce, and so
on, to take full advantage of peak times of solar energy and
down times of total darkness.

Plants are an obvious example. They photosynthesize
and make carbohydrates during the day, and then at night
they metabolize the food they made earlier that day to grow
new leaves, stems, and roots. Even humans have basic processes
that depend on whether we are awake or sleeping. At
night, for instance, the body increases its output of growth
hormones; this is when your skin cells regenerate, muscles
repair damage, and kids grow.

Sophisticated man-made machines, such as computers,
cars, and smart appliances, are a good analogy to help us
understand how central clocks or “oscillators” must oversee
complex systems. These machines need integrated clocks so
they can follow instructions, coordinate with other system
components, and track and respond to changing inputs and
conditions. But they don’t begin to compare to the circadian
clocks in living organisms, which clearly illustrate the
genius of our omnipotent Creator.

The Body’s Master Clock

When it’s time to translate one of
those glorious, sun-filled mornings into
a wake-up call that gets your body in
gear for another day’s activities, your
central master clock swings into action.
The all-important timekeeper is located
inside a region of your brain called the
hypothalamus. Not by accident, this
clock is ingeniously positioned directly
above the intersection between the two
optical nerves coming from your eyes—the ultimate light sensors.

This timekeeping computer, nestled inside the hypothalamus,
consists of a small cluster of about 20,000 neuron
cells and is called the suprachiasmatic nucleus. It’s the
headquarters that commands a wide array of nerves and
hormones to regulate many body functions over 24 hours.
Other parts of your brain and many organs throughout your
body wait for a bugle call from the suprachiasmatic nucleus
to get the day started.

Your Body Has Many Clocks

But this central body clock is just the beginning of the
amazing story. Humans, mice, and various animals not only
have a centrally located master clock in their brains, but they
also have many secondary (or “peripheral”) local clocks that
run the different organs, tissues, and individual cells throughout
their bodies. Moreover, just as a connected network of
computers keep their times synced with a central server, the
systems in your body keep their operations in perfect sync
with the brain’s central clock. This amazing Creator-designed
cellular communication unifies all the body parts and tissues
in a systems-critical, time-based context.

Researchers are just beginning to unravel the indescribable
complexity required to pull this off, and they are thoroughly
amazed at what they are finding. In fact, scientists
have now looked at many different tissues, including the
kidneys, liver, and intestines, and in nearly every case they
have found an independent clock that also takes cues from
the hypothalamus.

As it turns out, almost every cell in the human body has
a circadian clock. This enables each cell to figure out when
to use energy, when to rest, when to make repairs, or when
to divide and make more cells. For example, your body’s hair
cells divide at a particular time every evening (which means
your hair grows mostly at night).

Discovering Clock Genes

The daily cycle in animals and plants
has fascinated people for hundreds of
years, but it was only about 50 years
ago that scientists started investigating
the underlying biochemistry in earnest.
At an important meeting in 1960,
scientists at the famous genetics lab in
New York called Cold Spring Harbor
brainstormed about what genetic and
molecular processes might underlie
circadian rhythms, and they developed
experiments to test their theories.

The key circadian clock research
was identifying creatures with abnormal
daily cycles, such as mutant yeast
cells, fruit flies, and mice. By comparing
their genes and biology to their
normal counterpart creatures during
a 24-hour rhythm, they could discover
which genes are involved (because
they’re messed up in the mutants).
The biological revolution in the early
1970s, which opened the door to DNA
studies, provided the new tools to
unravel this mystery.

Among the most helpful lab subjects
were fruit flies that had out-of-whack
daily cycles (either 19 or 28 hours) or no
discernible rhythm at all. Research in
the humble fruit fly led circadian cycle
researchers to discover that a mutation
in one of its genes was behind this
abnormality. They cleverly named this
gene PERIOD in 1971. The PERIOD gene was later found to
produce proteins at different rates over the course of the day.

Interestingly, the lab workers discovered this variation in
gene activity because they did their experiments at different
times of day depending on their own aberrant circadian
rhythms—some were early risers while others were night
owls when they took their measurements.

Other fruit fly genes with similarly creative names soon
followed, like CYCLE, CLOCK, and TIMELESS. As it turned
out, all these genes play a role in regulating the cell’s processes
on a 24-hour cycle. They produce proteins, called
transcription factors, that act like master switches turning
other genes on and off in a highly coordinated, time-sensitive
process.

In addition to serving as genetic switches, a number of
these clock regulator proteins are so amazingly engineered
by an all-powerful Creator that they can also respond to
light. Some cells that have been cultured and studied in the
laboratory respond to the intensity of light or even the quality
or wavelength of light (such as blue light, in particular).

Circadian Clocks and Your Health

What does all that mean for us? Circadian clocks are critical
for good health. One of the most familiar examples is
jet lag. If you fly from California (Pacific time) to Virginia
(Eastern time), you lose three hours in your normal schedule.
When your alarm clock says it’s 8:00 the next morning,
your circadian clock says it’s 5:00. Eventually, your circadian
clock will adjust to the local time because of your amazing
sensory and response systems in play, but it will take several
days.

But scientists are coming to realize that our modern age
is creating all sorts of other difficulties that our pre-jet-age
ancestors never faced. Blue lights glowing on computer
screens late at night, fast food available at the snap of a finger
24 hours per day—such modern conveniences are contributing
to health conditions we never had before.

By improving our understanding of circadian rhythms,
scientists hope to find better treatments for sleep disorders,
weight management, good mental health, and even better
learning. (Yes, that’s right, most people have an optimum
time when they learn best.)

Consider household lighting and the light coming from
the electronic devices that we view at night just before we
go to bed. It appears that our body clocks are especially
designed to respond to a special wavelength in the visible
light spectrum called blue light. Blue wavelengths are beneficial
during normal daylight hours, boosting mood, attention,
and even reaction times. Viewing electronic screens
late at night, however, zaps you with blue light, confusing
your body into thinking it’s high noon. This can severely
reduce your ability to sleep, get you off schedule, and lead to
a variety of health problems.

Body Clocks Defy Evolution and Glorify God

Not even the most complex manmade
electronic device exhibits the
dynamic complexity found in the simplest
God-made biological systems.

Not even the most complex manmade
electronic device exhibits the
dynamic complexity found in the simplest
God-made biological systems.
Think about it—the human body has
trillions of cells, each with its own
clock, yet they constantly interact
with the other cells in their organ,
while they also take cues from the
main clock in the brain. The amount
of synergistic coordination and engineering
boggles the mind.

The magnitude of interconnectivity
and system complexity among
living creatures remains a daunting
challenge for human researchers to
understand and untangle, even with
modern tools of molecular biology and
genetics. Yet many scientists declare
with unflinching certainty that they
arose from the random, gradualistic
processes of evolution.

How much more intellectually satisfying
it is to view these interdependent
systems as prime examples of irreducible
complexity. The myriad, complex
components of the circadian clock system
had to be in place from the very
beginning for it to work, and it could
never have come about any other way.

Appealing to evolution to produce
the vast complexity God has engineered
into his creation is truly absurd.
Only an all-wise, all-powerful Creator
could have produced the incredibly
orchestrated system we find in circadian
clocks. In fact, God didn’t do it just
once, but in thousands of uniquely created
kinds of animals and plants (and
even in timekeeping single-cell bacteria!)
that inhabit this planet. Moreover,
these creatures have numerous creature-specific clocks suited to their special
needs. The more we understand
about the amazing systems in living
things, the more honor and glory we
should give their Creator.

https://answersingenesis.org/human-body/time-everything-your-body-internal-clock/

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