Spending too much time indoors may impair children's vision.

Children who spend more time playing outside are less likely to suffer from short-sightedness.Two new studies have added to the body of evidence that daylight plays an important role in preventing the condition.
It is not known why daylight is important but some experts believe levels of the brain chemical dopamine play a role. High levels of dopamine in the eyeball have been associated with a lower risk of short-sightedness.
Short-sightedness, or myopia, is an eye condition that causes a person to see things clearly close-up but struggle to see things when they are far away.
In childhood it is correctable, but it is also linked to the development of severe forms of the eye disorder in adulthood, which increases the risks for potentially blinding diseases such as glaucoma and retinal detachment.
Research on short-sightedness is intensifying as the condition nears epidemic status in Asia and other regions, primarily in developed countries。   Shockingly, it has increased by more than 65 per cent since 1970 in the U.S.
Although it often inherited, researchers are now assessing environmental factors to help explain why rates are rising so rapidly in some populations.
The Taiwanese study observed 333 students who spent their break between lessons in the playground. These children, many of whom had formerly spent recess indoors, now spent a total of 80 minutes per day outdoors.