Resynchronization of hormonal rhythms after an eastbound flight in humans: effects of slow-release caffeine and melatonin

Eur J Appl Physiol. 2001 Jul;85(1-2):144-50. doi: 10.1007/s004210100418.


The aim of this work was to investigate the potential chronobiotic properties of slow-release caffeine, in comparison with melatonin, on resynchronization of endogenous melatonin and cortisol secretions after an eastbound flight by jet incurring a time loss of 7 h. A group of 27 reservists of the US Air Force received either slow-release caffeine (300 mg), melatonin (5 mg) or placebo before, during and/or after the transmeridian flight. Saliva and urine were sampled before the flight in the United States (from day -2 to day 0) and after the flight in France (from day 1 to day 10). Saliva was collected once a day on waking to determine saliva melatonin and cortisol concentrations. In addition, concentrations of caffeine in saliva were determined three times a day and of 6-sulphatoxymelatonin in urine collected overnight to check that the treatment regimes had been complied with. From day 3 to day 5, post-flight saliva melatonin concentrations were significantly different from control values in the placebo group only. During treatment with melatonin, the mean urinary 6-sulphatoxymelatonin concentration in the melatonin group was more than twice as high as in the two other groups. In the slow-release caffeine group and the melatonin group, mean saliva cortisol concentrations were significantly lower than control from day 2 to day 5, whereas the placebo group had a mean saliva cortisol concentration significantly lower than the control value from day 2 to day 9. In conclusion, these results indicate that administration of slow-release caffeine, as well as of melatonin, allows a faster resynchronization of hormone rhythms during the 4 days following an eastbound flight incurring the loss of 7 h.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Adjuvants, Immunologic / administration & dosage*
  • Adjuvants, Immunologic / blood
  • Adult
  • Caffeine / administration & dosage*
  • Caffeine / pharmacokinetics
  • Central Nervous System Stimulants / administration & dosage*
  • Central Nervous System Stimulants / pharmacokinetics
  • Delayed-Action Preparations
  • Female
  • Humans
  • Hydrocortisone / analysis
  • Hydrocortisone / metabolism
  • Jet Lag Syndrome / drug therapy*
  • Jet Lag Syndrome / physiopathology
  • Male
  • Melatonin / administration & dosage*
  • Melatonin / analogs & derivatives*
  • Melatonin / analysis
  • Melatonin / metabolism
  • Melatonin / urine
  • Middle Aged
  • Saliva / chemistry


  • Adjuvants, Immunologic
  • Central Nervous System Stimulants
  • Delayed-Action Preparations
  • 6-sulfatoxymelatonin
  • Caffeine
  • Melatonin
  • Hydrocortisone