Navigation Links
'Food Clock' May Override Master Sleep Clock in Times of Duress

Mouse study suggests threat of starvation triggers the switch

THURSDAY, May 22 (HealthDay News) -- New animal research suggests the body's biological clock, which regulates sleep cycles based on the rise and fall of the sun, can be overridden in extreme situations by an internal "food clock."

The finding is based on work with mice and has not yet been tested among humans. But early indications are that, when faced with starvation, the animals automatically adjust their wake-sleep schedule to adapt to the best time to access food.

"In the wild, where starvation is a common threat, this must have evolved as a way for animals to lock onto a new food source, when necessary, to avoid starvation," said study author Dr. Clifford Saper, chairman of the department of neurology at Beth Israel Deaconess Medical Center and a professor of neurology at Harvard Medical School.

Saper and his team reported the findings in the May 23 issue of Science.

They noted that for animals and humans alike, the body's main clock is centered among a group of cells in the brain's hypothalamus region. Referred to as the "suprachiasmatic nucleus", this circadian clock is triggered by visual cues gleaned from the light-dark cycle. Such signals, in turn, activate cells that regulate sleep-wake cycles.

The authors speculated, however, that this standard "master" system could be overridden in situations of extreme duress -- such as starvation.

To test this theory and locate a possible "food clock," the researchers focused on mice genetically altered to lack a gene integral to the master biological clock.

After implanting the mice with transmitters to record body temperature and movement within plastic cages regulated for light and temperature, Saper and his colleagues then restored full light-clock function only to isolated parts of each mouse's brain throughout a rotating series of food deprivation experiments.

Successive two-week long tests were conducted in the context of both a normal light-dark cycle and then a constantly dark setting.

The result: The researchers uncovered the existence of a "feeding clock."

This clock, they noted, kicked into gear and effectively overrode the main light clock after just a single cycle of starvation followed by a re-feeding. The food clock, they concluded, actually hijacked the mouse's circadian rhythms and shifted its sleep-wake cycle to accommodate the need to be awake when food became readily available -- irrespective of the animal's light environment.

Among other things, the discovery of an animal food clock could theoretically lead to an improved method for dealing with jet lag among frequent travelers.

For example, Saper pointed out that while a time zone shift of 11 hours typically burdens our master light-dark clock with a week of difficult jetlag adjustment -- resetting just in time for the trip back home -- careful manipulation of a food clock could potentially render the shift painless and immediate.

"The punch line for humans is that this second clock may be a way for us to control our biological rhythms in shift work or when we travel," he observed. "In other words, it is possible that by fasting during a trip to Japan, then eating a hearty meal when you get there, you may be able to reset your clock much more quickly to the new time."

Ralph Downey III, chief of sleep medicine at Loma Linda University Medical Center at Loma Linda University Children's Hospital in California, described the research as thorough and interesting.

"It provides valuable insight into other possible clocks that time our behavior and time our sleep," he noted. "And it provides a little more complexity to our biology in terms of why we do things when we do them. So, we can see that there's a master clock, but interconnected with that clock are other clocks -- other spinning wheels. And while under normal circumstances the master clock works nicely, in extreme situations, the master clock can be overridden, which is a very adaptive thing that makes a lot of sense from an evolutionary perspective."

While equally intrigued, Dr. Emmanuel Mignot, director of the Stanford University Center for Narcolepsy, cautioned that the current research with animals still needs to be replicated in humans.

"However, this work opens up the idea that while there certainly is a central light clock, and clearly light does 90 percent of the regulatory job, other factors may come into play," he said.

"In fact," Mignot added, "I would say that in most cells in your body, you have a clock, and most of the time, these clocks talk to each other. Because the body is always prepared to anticipate different changes that should happen at certain times of the day. So, I wouldn't be surprise if there's a clock in your skin to anticipate light in the day, and a clock in your kidneys, so you are prepared to go the restroom. It's not just about being tired. It's pretty much every function that's regulated by the time of the day."

More information

For additional information on sleep and the circadian rhythm, visit the National Sleep Foundation.

SOURCES: Clifford Saper, M.D., Ph.D., chairman, department of neurology, Beth Israel Deaconess Medical Center, and professor, neurology, Harvard Medical School, Boston; Ralph Downey III, Ph.D., chief, Sleep Medicine, Loma Linda University Medical Center, Loma Linda University Children's Hospital, Calif.; Emmanuel Mignot, M.D., professor, psychiatry and behavioral sciences, and director, Stanford University Center for Narcolepsy, Stanford University School of Medicine, Palo Alto, Calif.; May 23, 2008, Science

Copyright©2008 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Eating junk food whilst pregnant and breastfeeding may lead to obese offspring
2. Scientists Develop Natural Protection for Stored Foods
3. New Survey Shows Americans are Still Concerned About Food Safety, Yet Still Not Smart About What They Like to Eat
4. Food Bank For New York City Acquires FoodChange
5. September: Time to Try Cholesterol-Free Soyfoods
6. Top Tips to Enjoy Healthy Latin Food Without Losing the Taste (Recipe)
7. Eat Seafood, See Weight Loss: Recent Study Finds Another Reason to Eat Seafood for a Fit Lifestyle
8. Food Additives Could Fuel Hyperactivity in Kids
9. Cutting Salt Wont Affect Foods Safety
10. American Diabetes Association and Goya Foods Inc. Team Up To Support Diabetes Awareness and Outreach in the Latino Community
11. U of M study: Health food supplement may curb addiction of pathological gamblers
Post Your Comments:
Related Image:
'Food Clock' May Override Master Sleep Clock in Times of Duress
(Date:11/30/2015)... , ... November 30, 2015 , ... ... only four states in the U.S. require dental technicians to be certified or ... dental industry, NADL created the “What’s In Your Mouth?” campaign to inform dentists ...
(Date:11/30/2015)... ... November 30, 2015 , ... MOSI recently added two ... along with Back to the Jurassic to their collection of interactive exhibits within the ... dynamic worlds that will allow guests to get closer than ever to a range ...
(Date:11/30/2015)... ... 2015 , ... In an effort to provide local families ... Christian Church of Flint, MI, hosted a family-oriented evening themed on “Candy Land”, ... candy dubbed “Candy Mountain”. , A Forever Recovery, a holistic treatment center for ...
(Date:11/30/2015)... ... November 30, 2015 , ... The presidential race normally deals with political issues ... it a national news story when Donald Trump makes disparaging remarks about Hillary Clinton’s ... more than anyone wants to admit when it comes to how people are viewed ...
(Date:11/30/2015)... ... November 30, 2015 , ... Rick Sommer, president of Intellitec ... Management of Information Systems course. Based in Wilmington Delaware, Intellitec Solutions is an ... before student in the Enterprise Resource Planning (ERP) Systems class. The course focuses ...
Breaking Medicine News(10 mins):
(Date:11/30/2015)... décembre 2015 MEDTEC Japon ... conférence d,Asie portant sur la conception ... manufacturière, se tiendra à ... 22 avril 2016. ... Photo - Logo ...
(Date:11/30/2015)... -- Nevro Corp. (NYSE: NVRO ), a global medical ... treatment of chronic pain, today announced that the Patent Trial ... Office (USPTO) has denied instituting an inter partes ... --> --> On ... two petitions challenging the validity of certain claims of the ...
(Date:11/30/2015)... 2015 Next week, December 2-3, BIOMEDevice ... ) co-located events covering the latest in Medtech innovation, ... will draw more than 3,000 design industry professionals to ... The events, combined show floor will host more than ... --> --> BIOMEDevice features suppliers ...
Breaking Medicine Technology: