Science/Medicine : Hamsters Shake a Leg to Overcome Jet Lag

An experiment with hamsters suggests that vigorous exercise after a long flight can lessen the malaise of jet lag, scientists say.

Hamsters that were made to run on a wheel for three hours after their days and nights were switched recovered significantly faster than hamsters that fell asleep, according to a new report in Nature Magazine.

Scientists say jet lag, punctuated by feelings of exhaustion, is due to physiological changes in the body that occur when the sleep-wake cycle is disrupted, such as after a flight to a different time zone.

Hamsters, which forage at night and sleep during the day, were chosen for the experiment because they are sensitive to changes in their cycles, said zoology professor Nicholas Mrosovsky of the University of Toronto.

In his experiment, which simulated what happens during eastward flight, Mrosovsky exposed hamsters to 14 hours of light and eight hours of darkness to simulate a normal day. Then he advanced daylight eight hours for the animals by making their rooms dark eight hours earlier and, following that, light eight hours earlier.

After the onset of darkness, half of the animals were allowed to go to sleep and half were put on exercise wheels in another part of the laboratory.

It took the running hamsters an average of only 1.6 days to adjust to the eight-hour time shift, compared with the 11.6-day average of the undisturbed animals.

"Of course you have to be careful extrapolating findings of a nocturnal animal like a hamster to a daytime-active animal such as a human, but the results bear looking into," Mrosovsky said.

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