The Health Benefits of Playing Outside

We've all heard that some germs are essential for health, but do we actually know why? And though microbes help build immunity, what about other aspects of health like allergies and emotional and physical development? Nathan H. Lents, Ph.D., a professor of Biology at John Jay College, weighs in on why exactly outside play is good for your child, from a holistic and data-driven perspective.

I like to fantasize that somewhere in our vast universe, there is a planet on which children joyfully accept a well-reasoned, research-backed answer for why they should or shouldn’t do things. However, here on planet earth, those data-driven explanations are mostly for parents to share among ourselves. This begs the question, why exactly do we insist that our children play outside? Are there concrete biological or developmental benefits? There definitely are, but three in particular stand out for including different modes of outdoor play and being backed by solid research.

Allergy Prevention

The explosion of food and environmental allergies in children over the last several decades initially puzzled public health scientists, but a large and growing body of research has largely solved this puzzle. The hygiene hypothesis holds that, during childhood, the healthy shaping of our immune system requires regular exposure to the friendly fire of non-harmful bacteria, viruses, and antigens. This makes sense because immunity is a very complex task and our immune system needs practice.

Of course, this goes against all of our natural instincts. We scrub or even sterilize everything that comes in contact with our children, but we may be doing more harm than good. It turns out, playing in the dirt, kissing dogs, handling bugs, and chewing on grass is probably exactly what our kids should be doing. And the danger is minimal. No one ever caught a cold from a dog.

Visual Benefits

Playing outside is also good for children’s eyes. Myopia (near-sightedness) is actually a scourge of modern habits, rather than an unavoidable fact of life. Somewhere around 40% of adults in Europe and North America, and close to 75% in Asia require corrective lenses because their eyeballs are too long. The incoming light falls out of focus by the time it reaches the retina.

Corrective lenses were not invented until the late Middle Ages. Before that, did the vast majority of people go around with poor eyesight? Almost certainly not. Recent studies in several different countries have shown that the more time that children stay indoors, the greater the chance that they require glasses as young adults. This is because being outdoors means that one spends much more time gazing at far-off objects. Apparently, kids’ growing eyes respond to that and develop into eyeballs that correctly focus light for distance vision.