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Study shows cycled light may help pre-term infants

A new study from the Medical Center indicates that a balanced amount of light--rather than round-the-clock darkness--may benefit premature infants. Healthcare officials have long considered continuous bright light harmful to the babies' health, leading them to use the near-darkness treatment.

The study showed that pre-term infants exposed to cycled light demonstrate more rapid weight gain and development than those kept in the near darkness, a method that seeks to imitate the womb.

Principal investigator Debra Brandon, associate professor of nursing, attributed the results to early stimulation of the circadian, day-night rhythms essential to human life.

"We know that circadian rhythms are important for growth in all beings," said Brandon, a clinical nurse specialist in the intensive care nursery. "The fetus grows in an environment rich in circadian rhythm through cues provided by the mother."

Brandon added that cycled light may help infants develop better sleeping patterns. "If they sleep better, hopefully they will grow better," she said.

She cautioned that cycled light, however, does not simply replicate the circadian rhythms of the womb. She and study co-author Diane Holditch-Davis, professor of nursing at the University of North Carolina at Chapel Hill, said that even if cycled light can replicate the day-night cycle, it can not simulate the mother's hormonal levels and digestive patterns.

During the study, researchers exposed 62 premature infants, all born before 31 weeks of gestation, to low-level light during the day and near-darkness at night. Some of them were exposed to cycled light at birth, others were exposed 32 weeks after conception and a final group was exposed 36 weeks after conception, just before they were discharged from the hospital.

The infants exposed to cycled light earlier gained weight faster and grew more quickly than those kept in near-darkness until just before hospital release.

Brandon said the limitations of the study included the small sample size and the fact that it did not investigate the long-term effects of cycled light. She said she hopes to further study the effects of cycled light on the auditory and visual systems of pre-term infants--this study showed small benefits to those systems, but Brandon cautioned that they may have been coincidental.

She also hopes to determine the stage at which cycled light is optimal. "At what gestational age is it best to receive cycled light?" she asked. "It is still unclear at what time cycled light should be instituted."

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