The benefit of daylight for our eyesight

What role does natural outdoor light play in developing the vision of our young children?

When children spend too many hours inside, their eyes fail to grow correctly.
When children spend too many hours inside, their eyes fail to grow correctly.

There is new evidence that suggests children who spend more time outside exposed to daylight may reduce their risk of developing nearsightedness. Research shows there has been an increase in the percentage of Americans ages 12-54 who are suffering from myopia over the past 45 years. The number has increased from 25 percent in early 1970 to 41.6 percent today. Myopia is also known as nearsightedness or not being able to see things far away. The American Academy of Ophthalmology and the National Eye Institute predict half the world’s population will be “nearsighted” by the end of 2050.

Being able to see long distances was important for our ancestors from long ago when they depended on their eyesight to hunt for food or watch for the enemy. They also spent a majority of their waking hours in the sun. Those without good long distance eyesight would have died off long ago and myopia would be a thing of the past – if it was strictly genetic. Our young kids are developing myopia at an earlier age than ever before, so one would wonder “what” is different today compared to several hundred years ago or even 45.

Genetics can always be blamed for the rise in myopia, but what is even a bigger culprit is not getting enough time outdoors in the natural light. Computers, iPads, television, reading and studying consume a lot of our time, so our eyes (and our bodies) are spending a lot less time outside. It certainly does not help when schools are cutting back on our kids’ recess time.

Dr. Christopher Starr, an ophthalmologist from Weill Cornell Medical College, suggests one to three extra hours per day should be spent outside. This is in addition to school recess time. Dr. Starr explains that dopamine, a known inhibitor of eye growth whose release is stimulated by light, prevents elongation of the eye. Lack of dopamine results in the eye becoming more elongated, resulting in nearsightedness.

Researchers suspect that bright outdoor light helps children’s developing eyes maintain the correct distance between the lens and the retina, which keeps vision in focus. Dim indoor lighting doesn’t seem to provide the same kind of feedback. As a result, when children spend too many hours inside, their eyes fail to grow correctly and the distance between the lens and retina becomes too long, causing far-away objects to look blurry.

Considering the following from “More Time Outdoors May Reduce Kids’ Risk of Nearsightedness,” published in American Academy of Ophthalmology August 2014:

  • Studying and reading increase the risk for myopia, but kids who played fewer sports outdoors showed more cases of myopia.
  • Kids with two myopic parents were at the greatest risk of developing myopia themselves. The chances increased significantly if they did not play sports.
  • Kids with no myopic parents and who also spent a lot of time outside had the lowest risk of all youth.
  • When children were allowed 80 minutes of recess during the school day, fewer became nearsighted when compared to children who were not required to spend recess outdoors. Many parents are already concerned about the lack of recess time during the school day. Recess is a right and now our kid’s eyesight depends on it.
  • Finally, one study showed that for each additional hour children spend outdoors per week, their risk of being nearsighted dropped by 2 percent.

A youth doesn’t have to play sports and definitely should not stare at the sun to reap the benefits daylight provides. Scientists believe general exposure through outdoor time, while still wearing UV blocking sunglasses and hats for protection from long-term UV damage, will also be effective. Studying and reading does not lead to nearsightedness. It is the lack of outside time that does. Being inside means less time outside. It’s the increase in outside time that is important.

Remember, every time we are in the sun without protection, we can be damaging our eyes. Too much exposure to UV rays without protective eyewear increases the risks of eye diseases including cataracts, growths on the eye or cancer. These diseases take many years to develop. For this reason, babies and kids need to wear hats and sunglasses as much as possible. Develop the habit while they are young. Sun damage can happen anytime of the year, even on a cloudy day. Sun reflecting off the snow can also cause painful damage. Everyone needs to protect their eyes.

Visit the following sources for additional information about myopia and the importance of outdoor time:

For more articles related to child development, please visit the Michigan State University Extension website.

Did you find this article useful?