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Developing circadian rhythmicity
1Department of Pediatric Endocrinology, Yale University School of Medicine, New Haven, CT, USA. Scott.Rivkees@Yale.edu
Insights
The developing circadian timing system is present prenatally and responsive to light in premature infants. Maturation of sleep-wake and hormone rhythms occurs after two months, highlighting the importance of circadian biology in neonatal care.
Area of Science:
- Chronobiology
- Developmental Neuroscience
- Neonatal Physiology
Background:
- Circadian rhythms are intrinsic biological cycles approximating 24-hours.
- The suprachiasmatic nuclei, the body's master circadian clock, form by midgestation in primates.
- The developing circadian system in primate infants demonstrates light responsiveness even at premature stages.
Purpose of the Study:
- To review the developmental trajectory of the mammalian circadian system.
- To highlight the role of light in regulating the fetal and neonatal circadian clock.
- To underscore the emerging significance of circadian biology in neonatal intensive care.
Main Methods:
- Review of existing scientific literature on circadian rhythm development.
- Analysis of evidence regarding prenatal and postnatal maturation of the circadian system.
- Examination of the impact of light exposure on the developing circadian clock.
Main Results:
- The human and nonhuman primate circadian timing system develops prenatally, with the suprachiasmatic nuclei present by midgestation.
- The immature circadian system in primate infants can be modulated by low-intensity light.
- Postnatal development shows progressive maturation of circadian outputs, with distinct sleep-wake and hormonal rhythms typically emerging after two months of age.
Conclusions:
- Circadian biology is a critical factor in fetal and neonatal development.
- Light exposure is a key regulator of the developing circadian system.
- Integrating circadian principles into neonatal care is essential for optimizing infant health and development.
Abstract:
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.