Science / Medicine : Body Clock Theory Challenged

A study questions the conventional view of how mammals keep the biological clock in their brains synchronized with the 24-hour day, researchers say.

The so-called circadian clock governs a host of body processes, and disruptions lead to such conditions as jet lag and some cases of insomnia.

Scientists generally believe that in most mammals, the brain maintains the clock’s 24-hour rhythm chiefly by monitoring light and darkness in the environment.

But the new study found that onset of darkness failed to exert its usual effect in hamsters if the animals were immobilized. So the real clock-setting mechanism may be the physical activity that darkness usually causes in hamsters, researchers suggest.

The work was presented in the British journal, Nature, by Fred Turek of Northwestern University and O. Van Reeth of the Free University of Brussels.