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 -- oth
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