Send to

Choose Destination
See comment in PubMed Commons below
Semin Perinatol. 2000 Aug;24(4):232-42.

Developing circadian rhythmicity.

Author information

Department of Pediatric Endocrinology, Yale University School of Medicine, New Haven, CT, USA.


Circadian rhythms are endogenously generated rhythms with a period length of about 24-hours. Evidence gathered over the past decade indicates that the circadian timing system develops prenatally, and the suprachiasmatic nuclei, the site of a circadian clock, is present by midgestation in human and nonhuman primates. Recent evidence also shows that the circadian system of primate infants is responsive to light at very premature stages and that low intensity lighting can regulate the developing clock. After birth, there is progressive maturation of the circadian system outputs, with pronounced rhythms in sleep-wake and hormone secretion generally developing after 2 months of age. With the continued elucidation of circadian system development and influences on human physiology and illness, it is anticipated that consideration of circadian biology will become an increasingly important component of neonatal care.

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Support Center