In 1999 a study out of the University of Pennsylvania School of Medicine reported an association between exposure
to nightlights as an infant and the subsequent development of nearsightedness (Nature 1999). Since then parents have been
asking physicians the question, "should I use a night light for my child?".
There were several problems with the study which limit its conclusion. One of the biggest weaknesses in the study
was that the researchers did not account for parental nearsightedness. Parents were not asked if they were nearsighted. Consequently,
it may be that the group of children who used night lights had parents who were nearsighted.
Another problem in the study was that the information was gathered when the children were much older. How many parents
can remember how much, how long, and how often a night light was used many years after the fact.
Two recent studies attempted to provide additional information on this subject (Nature 2000). In both studies no
association between exposure to night lights in infancy and nearsightedness in later life was found.
Children who slept
with night lights as infants had the same prevalence of myopia, when older, compared with children who did not use night lights.
Both studies also found that parents who were nearsighted tended to use night lights more often than parents who were
not. This may explain the findings in the original study since nearsighted parents are more likely to have nearsighted children.
So the next time a someone tells you they feel guilty about using a night light, tell them that current research
does not support a relationship between night light use as an infant and later development of nearsightedness. The decision
to use or not use a night light can be based on other factors such as childhood fears, the need to navigate around the room
at night, or the desire to make shadow puppets in the middle of the night!