The biological clock of very premature primate infants is responsive to light

Abstract

Each year more than 250,000 infants in the United States are exposed to artificial lighting in hospital nurseries with little consideration given to environmental lighting cycles. Essential in determining whether environmental lighting cycles need to be considered in hospital nurseries is identifying when the infant's endogenous circadian clock becomes responsive to light. Using a non-human primate model of the developing human, we examined when the circadian clock, located in the hypothalamic suprachiasmatic nuclei (SCN), becomes responsive to light. Preterm infant baboons of different ages were exposed to light (5,000 lux) at night, and then changes in SCN metabolic activity and gene expression were assessed. After exposure to bright light at night, robust increases in SCN metabolic activity and gene expression were seen at ages that were equivalent to human infants at 24 weeks after conception. These data provide direct evidence that the biological clock of very premature primate infants is responsive to light.

Reducing Light and Sound in the Neonatal Intensive Care Unit: An Evaluation of Patient Safety, Staff Satisfaction and Costs

“…In addition, we addressed emerging research on the importance of cyclical lighting to the emergence of circadian rhythms by instituting a formal policy requiring a minimum of 8 hours of ambient lighting at a level of 100 to 150 lx with reduced lighting in the evening and night. 18 Our study demonstrates that light and sound can be modified in an existing NICU at modest cost, without impacting patient safety. Although the modifications made are a start, additional improvements are possible.…”

Melanopsin-dependent light avoidance in neonatal mice

“…Even should ipRGCs not support image-forming vision, these photosensitive cells could regulate sleep/wake cycles and other well-known photo entrainable physiological processes. In support of this idea, light has been shown to control biological clock genes in premature primate infants (42), modulate heart rates in neonatal rat pups (43), and entrain pineal N-acetyltransferase rhythms in rat pups as young as P6 (44). In blind adult human patients lacking functional rod and cone function, blue light, by presumably activating melanopsin cells, was able to reset patients' circadian clocks and increase alertness (7) and exacerbate the intensity of migraine headaches (6).…”

Vesicular Glutamate Transporter 1 Is Required for Photoreceptor Synaptic Signaling But Not For Intrinsic Visual Functions

“…Therefore, VGLUT2-expressing neuronal pathways allow visual inputs to the brain at an age well before photoreceptors are functional. Although little is known about how light controls any behavioral or neuronal functions in neonatal rodents, it is known that the biological clock of premature primate infants is responsive to light (Hao and Rivkees, 1999).…”