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Airline pilots divided into two groups of age (over and under 50 years) were studied before, during and after westbound (Madrid-Mexico City-Madrid, n = 12) and eastbound (Madrid-Tokyo-Madrid, n = 21) flights. A group of 10 age-matched people staying in Madrid were submitted to the same tests and served as a control group. Changes in urinary 6-sulphatoxymelatonin (6-aMTs) and free cortisol excretion (determined in 6-hr intervals) were measured by radioimmunoassay. Using wrist actigraphy, the circadian locomotor activity rhythm (LAR) was also monitored. Maximal baseline excretion of 6-aMTs occurred between 00:00 and 12:00 hr and maximal excretion of cortisol took place between 6:00 and 12:00 hr in the control group. Analysed globally, older pilots exhibited significantly lower values of 6-aMTs than younger ones. In both flight directions, pilots maintained the pattern of excretion of 6-aMTs, corresponding to baseline. The return flight to Madrid from Mexico and Tokyo coincided with a maximum in 6-aMTs excretion. Pilots kept the cortisol pattern found in the control group, with those over 50 years of age exhibiting significantly lower cortisol values than the younger ones. A 7-hr delay in acrophase of LAR after 2 days in Mexico City was found after cosinor analysis, and similar pre-flight values were found after returning to Madrid. An 8-9-hr acrophase advance of LAR was observed after arriving in Tokyo, with acrophase on the post-return flight day still being advanced 3 4 hr as compared to pre-flight values. Decreases in the amplitude of LAR in older pilots were found at Mexico City, as well as at Tokyo stopover and on post-flight day. Data confirm the occurrence of internal desynchronization in airline crewmembers after transmeridian flights. |
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