Playing outside doesn't just boost the mood and provide an ample dose of vitamin D -- it could also have a protective effect on kids' eyesight.
New research from the University of Bristol suggests a link between playing outdoors and risk of myopia, or nearsightedness. People who are nearsighted are unable to see far-away objects clearly.
Specifically, 8- and 9-year-olds who played a lot outside had a halved risk of being short-sighted at age 15, compared with those who didn't play outside much, researchers found.
The researchers also found that the association persisted despite the amount of actual physical activity the kids got, which means that exercise likely wasn't the reason for the protected eyesight. The researchers also found that it didn't matter how much time the kids spent reading, or if their parents were also short-sighted.
"We're still not sure why being outdoors is good for children's eyes, but given the other health benefits that we know about we would encourage children to spend plenty of time outside, although of course parents will still need to follow advice regarding UV exposure," study researcher Dr. Cathy Williams said in a statement.
The study, published in the journal Investigative Ophthalmology & Visual Science, included more than 7,000 children who participated in the Avon Longitudinal Study of Parents and Children. The children received eye exams at age 7, 10, 11, 12 and 15, and researchers also noted their levels of outdoor play at age 9 and their levels of exercise (using an activity monitor) at age 11.
A review of studies from University of Cambridge researchers supports the new finding, showing that with every hour a child spends outdoors, his or her chance of being nearsighted decreases by 2 percent.
Nearsightedness is increasing. According to a 2009 study in the journal Archives of Ophthalmology, nearsightedness prevalence increased by 41.6 percent between 1999 and 2004, while it only increased by 25 percent in the 1970s.