Contrary to a study published last year, new research indicates that leaving a light on in a sleeping infant's room won't increase the child's chances of developing myopia.

In the current study of 1,220 children, researchers found no association between nighttime lighting and the development of myopia. It didn't matter whether the child had slept in a dark room, with a night light on or in a fully lit room. "In fact," says study co-author Karla Zadnik, "the proportion of myopic children across nursery lighting conditions was remarkably uniform."

Researchers found that of 417 children who had slept without a light on, 20% became myopic; of 758 children who had slept with a nightlight on, 17% became myopic; and of 45 children who had slept in a fully lit room, 22% became myopic. The average age of children surveyed was ten years.

The previous study didn't take into account parental myopia. The current study did take this into consideration. Zadnik found genetics play a significant role in causing myopia.