Study: Mealtime Changes Could Combat Jet Lag

W A S H I N G T O N, Jan. 19 -- The timing of meals may play an important rolein resetting body clocks, concludes a study that could aidscientists hunting ways to combat long-distance travelers’ jet lag.

The discovery, published in today's edition of the journalScience, is in rats, not travelers, scientists cautioned.

Still, "it's a noninvasive to change your eating habits," noteslead researcher Michael Menaker, a University of Virginiabiologist. "This would give you a reason to try it."

But more important than the nuisance of jet lag, Menakerstressed, the discovery that the liver resets its own biologicalrhythms according to eating habits also could point the way tobetter therapy for serious liver diseases.

Controlling Circadian Rythms

Everyone has a sort of master clock in the brain that controlstheir "circadian rhythms," biological patterns such as sleep andbody temperature. This brain clock is very light sensitive, thereason most people sleep at night and wake during the day. Travelto a greatly different time zone, however, and it can take a whilefor that master brain clock to adjust.

Then scientists discovered the brain-based clock isn't the onlycontrol of circadian rhythms. Other organs seem to have their ownclocks that supplement the brain's master clock. Perhaps that's whysleep problems aren't the only jet lag symptom; lots of suffererscomplain of stomach upset and other problems, too.

Menaker simulated jet lag by exposing rats to light six hoursearlier than they'd normally wake. While the light-sensitive brainclock could adjust in a few days, the rats' separate livercircadian rhythms were out of sync for up to two weeks.

The liver helps control food metabolism. So Menaker, workingwith scientists in Norway and Japan, wondered if changing mealtimeswould reset the liver's own circadian rhythm and thus help readjustthe overall body clock.

They tested rats genetically engineered to carry afluorescent-stained clock-related gene — when and how much therats' liver tissue glowed under a microscope showed allowedmeasurement of the liver's circadian rhythms.