Jet lag linked to memory, brain changes

BERKELEY, Calif., Nov. 25 (UPI) -- In a study using hamsters, U.S. researchers say they found persistent changes in the part of the brain dealing with memory of the animals subjected to jet lag.

Psychologists at the University of California, Berkeley, subjected female Syrian hamsters to 6-hour time shifts -- the equivalent of a New York-to-Paris airplane flight -- twice a week for four weeks.

During the last two weeks of jet lag and a month after recovery from it, the hamsters' performance was tested.

The study, published online in the journal PLoS ONE, found during the jet lag period, the hamsters had trouble learning simple tasks, but the hamsters in the control group did well at the tasks.

However, the deficits in performing the tasks persisted for a month after the hamsters returned to a regular day-night schedule.

"This is the first time anyone has done a controlled trial of the effects of jet lag on brain and memory function, and not only do we find that cognitive function is impaired during the jet lag, but we see an impact up to a month afterward," Lance Kriegsfeld of the University of California, Berkeley, and a member of the Helen Wills Neuroscience Institute, said in a statement.

"What this says is that, whether you are a flight attendant, medical resident, or rotating shift worker, repeated disruption of circadian rhythms is likely going to have a long-term impact on your cognitive behavior and function."