The finding may explain, at least in part, why transmeridian travelers suffer from jet lag, the malaise experienced after crossing several time zones. The new understanding could eventually lead to the development of medicines that would "reset" the biological clock so travelers could adjust much more quickly to rapid time zone changes. Most people require about two-and-a-half days to adjust to a six-hour flight from Europe to the United States, and even longer after an eastbound trans-Atlantic flight. The study also has implications for ways to treat shift workers - health care providers, factory employees, truck drivers, etc. - who encounter alertness problems, and those with sleep disorders.
A team of researchers at the University of Virginia and at Leiden University Medical Center in the Netherlands published their findings in the May 24 - June 6, 2005 issue of the journal Current Biology.
The investigators found that the dorsal and ventral sections of the suprachiasmatic nucleus (SCN), the brain's central timekeeper, adjust to shifts in light schedules at vastly different rates, potentially causing the difficult period of adjustment that most people experience after air travel across several time zones.
The researchers found that the ventral part of the SCN, which is directly connected by a nerve to the light-sensing retina, synchronizes rapidly with a new light schedule, even a radically shifted schedule. But the dorsal part of the clock requires several additional days to adjust. This results in complex signaling patterns that may adversely affect the functioning of tissues and organs throughout the body for a period of several days.
Importantly, the study identifies
Source:University of Virginia