“ It turns out the brainiacs of the marine world
can also be tool-using workaholics... ” —JANET MANN, PAGE 13
In the News
Atom & Cosmos A planet with atmosphere
Dark energy — it’s constantly repulsive
Earth Inner turmoil for young Earth
Humans Gift givers: Money can’t buy love
Life Dolphins on the hunt, sponges ready
Body & Brain Circumcision demand jumps
Vaccine takes swipe at malaria in children
STORY ONE
Gene connects
lack of shut-eye
with diabetes
Studies reveal how sleep can
influence blood sugar levels
By Laura Sanders
S leep is a mystery. Although it’s
required for good health, no
one knows exactly why. But
now scientists have found a
surprisingly clear connection between
sleep and a healthy body: the regulation
of sugar in the blood. Three new studies report the first known genetic link
between sleep and type 2 diabetes, a disease marked by high blood sugar levels.
In the United States, the average
amount of time that people sleep is
dwindling, the Centers for Disease Control and Prevention has reported. And
cases of type 2 diabetes are increasing.
In papers published online December 7
in Nature Genetics, three international
teams suggest that the trends of rising
diabetes and diminishing sleep are linked
via a protein that senses the sleep-inducing hormone melatonin. The research
places body rhythms, including the clock
that sets human sleep cycles, squarely in
the blood sugar business.
This newfound link between melatonin and type 2 diabetes intrigues
sleep researcher Orfeu Buxton of Harvard Medical School in Boston, who was
not involved with the new work. “This is
really breakthrough stuff,” he says.
MTNR1B
Insulin
Merged
Mouse Rat Human
Rodent and human cells that produce insulin (red) are studded with proteins (green)
that sense melatonin, a sleep hormone. The bottom row shows overlap (yellow).
ular details about how sleep can change
blood sugar levels. The key, it appears,
is a receptor protein on the outside of
cells that binds to melatonin and triggers
sleep- or wake-related changes in cells.
The human body has an internal clock
that dictates when to fall asleep and when
to get up. The clock is set by molecular
timekeepers that are made and degraded
on a 24-hour cycle. If part of the clock
goes awry, sleep schedules change.
Disordered sleep can spark a constellation of intertwined pathologies: Studies
in humans have shown that depression,
obesity, weakened immune system function and even death correlate with a lack
of shut-eye. Population studies have
shown that diabetes rates rise as sleep
declines. While such research provides
compelling reasons to get eight hours
of quality sleep every night, it doesn’t
explain how sleep could affect diabetes.
But the new studies show that melatonin, a major regulator of the body’s
sleep clock, is closely linked to increased
glucose levels and diabetes. Best known
for its role in sleep, melatonin is sold as
an over-the-counter nutritional supplement to aid sleep. Melatonin levels in
the body are tied to daylight: When the
lights go down, melatonin levels rise, and
drowsiness soon follows. ®®
