Chronome assessment of circulating melatonin in humans

In Vivo. Nov-Dec 1997;11(6):473-84.


Background: Melatonin (MEL) production occurs mainly during the dark span. A prominent circadian variation is demonstrated in both blood and urine in humans.

Materials and methods: The circadian, circannual, age and gender patterns of MEL were concomitantly investigated in 40 men and 132 women, each providing blood samples every 4 hours for 24 hours for conventional and cosinor analysis.

Results: Circulating MEL is circadian periodic (P < 0.001), peaking at night. The MESOR (rhythm-adjusted mean) is higher in women than in men. The circadian amplitude decreases with age. Both are modulated by a circannual variation, the MESOR peaking in winter (P < 0.001) and the circadian amplitude in summer (P < 0.05).

Conclusions: Samples, unqualified as to gender, age and/or season, incompletely characterize the circadian MEL patterns. This chronome approach detects changes that may escape detection otherwise, checking whether a value is too high or too low, and also whether "swinging" occurs to the right extent.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aging / metabolism
  • Circadian Rhythm
  • Diabetes Mellitus / blood
  • Female
  • Glucose Intolerance / complications
  • Humans
  • Male
  • Melatonin / blood*
  • Middle Aged
  • Periodicity*
  • Seasons
  • Sex Characteristics


  • Melatonin