One thing you probably have come to expect from air travel is bad food. One thing you DON'T expect is brain damage! However, a paper published in Nature Neuroscience (June 2001), suggests that chronic jet lag can raise stress hormones, interfere with memory and reduce the size of the brain's temporal lobe.

Dr. Kwangwook Cho of the Department of Anatomy at the University of Bristol studied two groups of female flight attendants who were between 22 and 28 years old, were college graduates and had five years of flight experience. The only difference between groups was the amount of time the attendants were permitted to rest between flights across at least seven time zones. The "short-recovery crew" had only 5 days between flights; the "long-recovery crew" had at least 14 days between flights. During the jet lag recovery, the long-recovery crew flew on shorter flights that did not have large time shifts. Therefore, both groups flew about the same amount.

Using magnetic resonance imaging methods, Dr. Cho found that the right temporal lobes of the short-recovery crew were smaller than those of the long-recovery crew. Higher levels of cortisol (a stress hormone) in the short-recovery crew were found in short-recovery crew members with smaller temporal lobes. Moreover, the short-recovery crew performed more poorly on a visual spatial cognitive test compared with the long-recovery crew.

These data suggest that chronic shifting of sleep cycles, without sufficient time to recover, may have a damaging effect on the brain. This may have serious implications for people in the travel industry (flight attendants and pilots), shift workers, and parents with young children. It is unknown if the damage to the temporal lobe is permanent or if sufficient rest can reverse these changes.

• Cho, K., Chronic 'jet lag' produces temporal lobe atrophy and spatial cognitive deficits. Nature Neuroscience, 4:567-568, 2001.