Diurnal rhythms of cortisol, ACTH, and beta-endorphin levels in neonates and adults

West J Med. 1989 Aug;151(2):153-6.


To determine whether a diurnal rhythm exists in neonates admitted to neonatal intensive care units where there is continuous artificial lighting and periodic nursing and medical care, plasma cortisol, adrenocorticotropin (ACTH), and beta-endorphin concentrations were measured in two groups of infants and in adult human volunteers. As expected, a diurnal rhythm was seen in adults. A diurnal rhythm was also found for cortisol and endorphin levels in neonates (3 to 4 days postnatally) with minimal stress and in infants who were clinically severely stressed. There was not a significant difference between the morning and afternoon concentrations of ACTH in these infants, but the afternoon concentrations were lower than the morning's, as would be expected. We found that a diurnal rhythm does exist in neonates within the first few days of postnatal life and that the continuous lighting and medical and nursing interventions do not interfere with this rhythm.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenocorticotropic Hormone / blood*
  • Adult
  • Circadian Rhythm*
  • Humans
  • Hydrocortisone / blood*
  • Infant, Newborn
  • Intensive Care Units, Neonatal
  • Stress, Psychological / blood
  • beta-Endorphin / blood*


  • beta-Endorphin
  • Adrenocorticotropic Hormone
  • Hydrocortisone