Jet-lag causes memory loss

Washington : International travellers may feel tired and forgetful for up to a month after returning to a normal schedule because jet-lag causes long term changes in the brain, a US study said on Wednesday.

Similar brain disruptions could be experienced by anyone who works alternating night-day shifts or unusual schedules, said the study which is the first to look at long-term effects of such lifestyle changes on brain anatomy.

"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 behaviour and function," said Lance Kriegsfeld, associate professor of psychology at the University of California at Berkeley.

The researchers subjected female hamsters to six-hour changes in schedule — similar to a New York to Paris flight — twice a week for four weeks.

As expected, the harried hamsters had trouble learning simple tasks that other, more rested hamsters aced during the four-week period. But more surprisingly, the learning problems persisted for a month after they settled back into a normal schedule.

Drop in neurons

Researchers say they were able to track the changes to a drop in neurons in the hippocampus, which is the part of the brain responsible for memory.

"Compared to the hamsters in the control group, the jet-lagged hamsters had only half the number of new neurons in the hippocampus following the month long exposure to jet lag," said the study published in the journal PLOS One.