The Connection Between Sleep and Appetite

Eating and sleeping are two of the most basic human
functions, both essential to survival. They are also two biological processes
that are deeply entwined, as science is increasingly discovering. There are
foods that promote
sleep (including potassium-rich fruits and dark leafy greens) and foods that
can interfere
with sleep (think high-fat snacks).  Too
much or too little sleep alters
appetite and wreaks havoc with hunger-related hormones. Going without enough
sleep makes junk food look more tempting,
and increases desire for fatty and high-calorie foods. Staying up late at night
often leads to greater overall calorie consumption
and makes us more prone to putting on weight. On the other hand, high-quality,
restful sleep in moderate amounts (not too little, not too much) has a positive
influence
on long-term weight control.

New research gives us a glimpse of just how deeply connected
sleeping and eating may be. Scientists have discovered
in fruit flies that a brain molecule already known to regulate appetite may
also play an important role in sleep regulation. Researchers at Brandeis
University found
that a neuropeptide in the fruit fly brain, already recognized as a regulator
of eating, also can dramatically influence sleep and activity levels. Neuropeptides
are molecules that enable communication among cells in the brain, and are
involved in regulating a number of important physiological processes, including
appetite and metabolism. Researchers examined the possible role in sleep
regulation of a particular neuropeptide, known as sNPF, that is already known
to regulate food intake
and metabolic
function. Researchers manipulated the sNPF neuropeptide in fruit flies to see
what effects this had on sleep and activity levels. They found that altering
the activity of sNPF had a dramatic, sleep-inducing effect on the flies:

  • When sNPF was activated above normal
    levels, fruit flies fell asleep almost immediately
    .
  • Flies slept excessively and activity
    levels dropped dramatically after sNPF activation
    . The flies woke from
    sleep in order to eat or to locate a new food source and then fell back
    asleep.
  • When
    sNPF levels were returned to normal, the fruit flies’ sleep habits changed
    and the flies returned to normal sleeping patterns and activity levels.
  • The
    activation of sNPF that changed sleep patterns and activity levels in the
    fruit flies did not alter feeding behavior in the short term.

What does this discovery mean? It provides new window into
the neurological connection between sleeping and eating. These findings on
their own don’t explain how the physiological mechanisms behind sleeping and
eating are related or influenced by one another.  But the identification of a shared signal
that regulates both eating and sleeping establishes an important and very
tangible neurological connection between the two functions. Other recent
research also has explored the brain-based connections between sleeping and
eating, and the possible implications for weight control:

Researchers at University of California, Berkeley investigated
the effects of sleep deprivation on brain functions related to food choices.
Using MRI scans, scientists observed the neurological activity of
sleep-deprived and well-rested people as they viewed pictures of a range of
healthful and unhealthful foods. The scans revealed that the reward center of
the brain responded more strongly to images of high-calorie foods among the
sleep-deprived group than the well-rested group. The MRI scans also showed that
sleep deprivation decreased activity in the area of the brain that regulates
behavior control. This study suggests that
insufficient sleep has a two-fold effect on eating—not sleeping enough makes us
more inclined to eat poorly, and at the same time less able to exert control
over our impulses to eat those not-good-for-us foods
.

Scientists at St. Luke’s-Roosevelt Hospital Center and
Columbia University also examined the
effects of sleep deprivation on neurological responses to food. Researchers
used MRI scans to observe brain activity among two groups of healthy-weight
adults—one group had received several full nights’ of sleep, and the other
group had been limited to no more than 4 hours of sleep per night for 5 nights.
The sleep-restricted group demonstrated
greater activity in the reward center of the brain when looking at pictures of
junk food.
MRI scans showed the reward centers of sleep-restricted subjects
did not react to the sight of healthful foods this way. The well-rested group
did not display this heightened reward-center response to images of junk food.

Both sleep problems and metabolic problems associated with
overeating pose significant challenges to long-term health. Disrupted and
insufficient sleep has become an increasingly common problem
over the past several decades, contributing to the risk of a number of serious
diseases, including cardiovascular
disease, some types of cancer,
and diabetes.
Obesity is a significant public health problem in the United States. The rise in
the rate of obesity is slowing
somewhat after decades of
sharp growth. Still, by 2030, projections
suggest that more than 40% of U.S. adults will be obese.

Understanding the relationship of sleep to food
consumption, weight regulation, and metabolism is critical work. Identifying a
single neurological molecule that helps regulate both sleeping and eating is a
significant development in that understanding. There is much more to learn
about the relationship between sleeping and eating—and how we can use that
relationship to foster weight loss and improve overall health. But this latest
discovery could be one important piece of the sleep-weight puzzle.

Sweet Dreams,

Michael J. Breus, PhD
The Sleep Doctor®
www.thesleepdoctor.com

The Sleep Doctor’s Diet
Plan:  Lose Weight Through Better Sleep

Everything you do, you do better with a good night’s sleep™
twitter: @thesleepdoctor  @sleepdrteam
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Michael Breus, Ph.D - The Sleep Doctor is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan and Good Night!

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