A study of 20 flight attendants suggests that people who undergo repeated, frequent episodes of jet lag without sufficient recovery time between trips may develop actual tissue changes in the brain in an area that's involved in spatial orientation and related aspects of cognitive function. The extent to which this is due to sleep deprivation rather than time shifts per se is unknown. These findings may also be relevant to shift workers, medical trainees and others who work long hours.
 . Chronic 'jet lag' produces temporal lobe atrophy and spatial cognitive deficits. Nat Neurosci [Internet]. 2001 ;4(6):567 - 568. Available from: http://dx.doi.org/10.1038/88384