Time-zone travelers encounter a pattern of light and darkness, and their endogenous circadian rhythms adapt to the new external time cue until both timing systems synchronize 1, but the long-term repeated disturbance of synchronization between the two timing systems impairs physiological and psychological health and induces stress 2. Salivary cortisol levels in cabin crew after repeated exposure to jet lag were significantly higher than after short distance flights 3, and the higher cortisol levels were associated with cognitive deficits that were dependent on non-semantic stimuli 3. The present study demonstrates that significant prolonged cortisol elevations produce reduced temporal lobe volume and deficits in spatial learning and memory; these cognitive deficits became apparent after five years of exposure to high cortisol levels.