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THURSDAY, July 3, 2003 (HealthDayNews) --
Your desire for an afternoon snooze doesn't necessarily mean you're lazy.
You may just be following instructions from your body clock, says an American study in the July 4 issue of Science.
The study of mice found the circadian clock that controls the body's daily rhythms may have two main components. One is for light-controlled rhythms and the other is for sensory-controlled rhythms.
The researchers say their findings indicate the interplay between these components is responsible for daily cycles of sleep and activity and may let mammals be more adaptable to changing environmental conditions.
This interplay may also be responsible for your tendency to become tired at midday, the researchers say.
The study notes it's long been believed the brain's suprachiasmatic nucleus (SCN) houses the body's master clock, which is regulated in part by a protein called CLOCK in response to light-related information delivered from the eyes.
While other parts of the body have their own circadian clocks, the clock in the forebrain is unusual in that it's regulated by a protein called NPAS2 instead of CLOCK.
In this study, the researchers knocked out the NPAS2 gene in a strain of mice. The scientists found these mice were less sensitive to changes in daily light cycles than normal mice. The altered mice were also less able to adapt to a restricted feeding schedule. Normal mice are able to do that by changing the time they eat.
More information
Here's where you can learn more about the biological clock.
