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Emergence and evolution of the circadian rhythm of melatonin in children

Julio Ardura1, Regina Gutierrez, Jesus Andres

  • 1Department of Pediatrics, University Hospital, University of Valladolid, Spain. ardura@ped.uva.es

Hormone Research
|February 18, 2003
PubMed

Insights

The circadian melatonin rhythm emerges in newborns by 27-41 days old and continues throughout infancy. This study tracked melatonin levels in infants to determine when this daily rhythm begins.

Area of Science:

  • Pediatrics
  • Chronobiology
  • Endocrinology

Background:

  • The circadian rhythm of melatonin, a key hormone regulating sleep-wake cycles, is crucial for infant development.
  • Understanding the onset of this rhythm is vital for assessing normal physiological development in early life.

Purpose of the Study:

  • To determine the precise age at which the circadian rhythm of melatonin production begins in human infants.
  • To investigate the persistence of this rhythm from the neonatal period through early childhood.

Main Methods:

  • Studied 55 infants from the neonatal period to 24 months.
  • Measured urinary 6-sulfatoxymelatonin (aMT6s) in newborns and salivary melatonin (aMT) in older infants.
  • Utilized ELISA and RIA for hormone quantification and statistical tests to analyze daily variations.

Main Results:

  • Statistically significant daily differences in melatonin concentrations were observed in infants aged 27-41 days.
  • Peak melatonin levels consistently occurred between midnight and 8:00 AM.
  • This day/night pattern persisted from 2-3 months up to 13-24 months of age.

Conclusions:

  • The circadian melatonin rhythm is established by the end of the neonatal period in infants.
  • This rhythm demonstrates developmental continuity, persisting throughout the first two years of life.
Abstract

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