Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How do animals exposed to 24-hour light retain their wake-sleep habits?

19.04.2004


The phrase "biological clock" has expanded from scientific observation to American slang. When we hear this phrase, many of us assume it refers to the amount of time left for a woman to start a family. For the scientist, the biological clock refers to a process that took millions of years to evolve – the conditioning of plants and animals by a light cycle that starts with dawn and ends with sunset.



The cycle of dawn and dusk changes with the seasons everywhere in the world (except at the equator, where there is always 12 hours of daylight and 12 hours of darkness). In order to compensate for the seasonal variations of light, mammals likely have an adjustable daily program under the regulation of a biological clock.

But how do mammals in the Arctic – which is characterized by months of full light followed by months of full darkness -- retain their sleep and awake habits in such unusual circumstances? After analyzing the reactions of certain mammals following 82 days of continuous daylight in the summer and 82 days of continuous darkness in the winter, a team of researchers may have begun to identify a clue.


A New Study

The research is captured in a presentation entitled, "Cardiac Physiology of Mammals in Arctic Light Cycle: Heart Rates and Biological Clocks." The authors, G. Edgar Folk, Diana L. Thrift, James B. Martins, and Miriam B. Zimmerman, all from the University of Iowa, Iowa City, IA, will present their findings at the American Physiological Society’s (APS)(www.the-aps.org) annual scientific conference, Experimental Biology 2004, being held April 17-21, 2004, at the Washington, D.C. Convention Center.

Methodology and Results

The researchers analyzed the biological clocks using cardiac physiology. They recorded the mammals’ daily circadian rhythm using heart rate to show the rhythm of sleep and wakefulness.

Control laboratory rats (N=4) were exposed to artificial continuous light and demonstrated the Aschoff effect, where the circadian activity pattern changes quantitatively with the intensity of the light. This group took on a 26-hour day.

This was not the case when the experiment was repeated in the field at the Naval Arctic Research Laboratory - with two species of Arctic rodents exposed to continuous daylight (nocturnal porcupines [Erethizon] N=4, and hibernators, the Arctic ground squirrel [Spermophilis] N=6). Under these circumstances, both species had a specific time of sleep and of wakefulness. In fact, the Arctic rodents, which had undergone 82 days of continuous sun above the horizon, had a crisp, 24-hour day-night rhythm of sleep and wakefulness.

Conclusions

The free-living animals in the Arctic had regular sleep-awake cycles, despite having 82 days of continuous sun. The intriguing question is whether or not these animals have found a clue in the external environment to take the place of the missing sunset. The researchers hypothesize that because the sun during this period is nearer the horizon at one part of the day, this might act as a clue for the biological clocks.

As the American economy requires its work force to abandon traditional work hours of "nine to five," it becomes more important for us to understand how the body’s biological clock can respond to unnatural light clues and adapt to a changing environment. This study is another step in the continuing research towards such comprehension.


The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 11,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.

Editor’s Note: For further information or to schedule an interview with a member of the research team, please contact Donna Krupa at 703-967-2751 (cell), 703-527-7357 (office) or at djkrupa1@aol.com. Or contact the APS newsroom at 202-249-4009 between 9:00 AM and 6:00 PM EDT April 17-21, 2004.

Donna Krupa | EurekAlert!
Further information:
http://www.the-aps.org/

More articles from Life Sciences:

nachricht Research team creates new possibilities for medicine and materials sciences
22.01.2018 | Humboldt-Universität zu Berlin

nachricht Saarland University bioinformaticians compute gene sequences inherited from each parent
22.01.2018 | Universität des Saarlandes

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>