Children who sleep with a light on in their bedrooms at night before the age of 2 may be at significantly higher risk of developing myopia - near-sightedness - when they become older than children who sleep as infants in the dark at night, according to a collaborative study by researchers at the University of Pennsylvania Medical Center and The Children's Hospital of Philadelphia. A report on the findings will appear in the May 13 issue of Nature.
The team's results showed that, of children aged 2 to 16 who had slept in darkness before age two, 10 percent were myopic at the time of the study. Of children who had slept with a night light on before age 2, 34 percent were myopic. And of children who had slept at night with a room light on before age 2, 55 percent were myopic - more than a five-fold increase over the children who slept in darkness during early childhood.
"Our findings suggest that the absence of a nightly period of full darkness in early childhood may be an important risk factor in the future development of near-sightedness," says Richard A. Stone, MD, a professor of ophthalmology at Penn's Scheie Eye Institute and senior author on the study. "The study does not establish that nighttime lighting during early childhood is a direct cause of myopia, and there are undoubtedly other risk factors. Still, it would seem advisable for infants and young children to sleep at night without artificial lighting in the bedroom until further research can evaluate all the implications of our results."
Near-sightedness is more than a minor inconvenience to be corrected with glasses or contact lenses, the scientists emphasize.
"Especially in the more severe degrees, myopia itself is a leading risk
factor for acquired blindness, putting individuals at increased risk for retinal
detachment, retinal degeneration, and glaucoma," says Graham E. Quinn, MD, a
pediatric ophthalmologist at The Children's Hospital of Phila
Contact: Franklin Hoke
University of Pennsylvania School of Medicine