(November 24, 2010) Chronic jet lag alters the brain in ways that
cause memory and learning problems long after one’s return to a regular 24-hour
schedule, according to research by University of California, Berkeley,
psychologists.
Twice a week for four weeks, the
researchers subjected female Syrian hamsters to six-hour time shifts – the
equivalent of a New York-to-Paris airplane flight. During the last two weeks of
jet lag and a month after recovery from it, the hamsters’ performance on
learning and memory tasks was measured.
As expected, during the jet lag
period, the hamsters had trouble learning simple tasks that the hamsters in the
control group aced. What surprised the researchers was that these deficits
persisted for a month after the hamsters returned to a regular day-night
schedule.
What’s more, the researchers
discovered persistent changes in the brain, specifically within the
hippocampus, a part of the brain that plays an intricate role in memory
processing. They found that, 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. New neurons are constantly being
added to the adult hippocampus and are thought to be important for
hippocampal-dependent learning, Kriegsfeld said, while memory problems are
associated with a drop in cell maturation in this brain structure.