Daniel Désir

Adaptation of 24-hour hormonal patterns and sleep to jet lag.

Effects of rapid transmeridian time shifts on behavioral and biological parameters such as vigilance, heart rate, and urinary excretion of electrolytes and corticosteroids have been demonstrated (1, 2, 3). Because of the key role played by hormones in the adaptation to the environment, disruptions in the temporal organization of hormonal secretion might be involved in the production of the jet lag syndrome. The current availability of sensitive hormone assays has made it possible to test this hypothesis. Moreover, assessment of jet lag induced changes of the 24-h hormonal profiles and their pattern of adaptation is expected to bring further insight into the control of the various hormonal rhythms, the identity of their zeitgebers and their possible interrelationships.

Hormonal changes as a consequence of jet lag : corticotrophic axis

Five normal male volunteers were subjected to seven consecutive studies at 10-day intervals over a total period of 10 weeks. The investigation comprised a basal study in Brussels, a westward 7-hour time shift to Chicago, three studies in Chicago, an eastward flight back to Brussels, and three studies in Brussels. During each study, blood was drawn at 15 min intervals for 25 hours. Plasma adrenocorticotrophic hormone (ACTH) and Cortisol were measured in each sample. No quantitative alterations of the adrenocortical secretion were caused by jet lag. In all subjects the temporal organization of ACTH and Cortisol secretion was disrupted by the time shifts for at least 11 days after the flights. A dissociation in the rapidity of the adaptation of the time of maximal secretion and of the quiescent period was observed. This suggests that the maximal and minimal secretory periods may be controlled by different mechanisms.