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 has recently said.
Similar brain disruptions could be experienced by anyone who works alternating night-day shifts or unusual schedules, said the study. “What this says is that, whether you are a flight attendant, medical resident, or rotating shift worker, repeated disruption (of the metabolic cycle) is likely 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. Researchers used hamsters because they have precise metabolic rhythms, driven by an internal, 24-hour clock, just like humans.
The finding could have wider implications for shift workers and frequent long-distance travellers, who have already been found to suffer “decreased reaction times, higher incidences of diabetes, heart disease, hypertension and cancer, and reduced fertility,” the study said.
To ward off the effects, Kriegsfeld advises allowing one day of recovery for every one-hour time zone shift. Night shift workers should sleep in a dark, quiet room to adjust their bodies to their altered schedule.