Abstract: The present invention relates to a modulator of glucocorticoid biosynthesis, degradation and/or receptor activation for use in preventing or treating symptoms and/or diseases associated with jet lag. The compositions of the invention may be used as a lead compound for developing a drug for preventing or treating symptoms and/or diseases associated with jet lag. The invention relates to the discovery that administration of the modulator(s) to a subject results in a directional change of the time point of maximum amounts of glucocorticoids in the subject as compared to the time point of maximum amounts of glucocorticoids in a subject not treated with the modulator(s).