1. It changes brain structure in important ways

In a recent interview on NPR's Morning Edition, Sergio Pellis, Ph.D., an expert on the neuroscience of play noted that play actually changes the structure of the developing brain in important ways, strengthening the connections of the neurons (nerve cells) in the prefrontal cortex, the area of the brain considered to be the executive control center responsible for solving problems, making plans and regulating emotions.

Because unstructured play involves trying out different strategies without particular goals or serious consequences, children and other animals get to practice different activities during play and see what happens. When Dr. Pellis compared rats who played as pups with rats that did not, he found that although the play-deprived rats could perform the same actions, the play-experienced rats were able to react to their circumstances in a more flexible, fluid and swift fashion.

Their brains seemed more "plastic" and better able to rewire as they encountered new experiences.

Hod Lipson, a computer scientist at Cornell sums it up by saying the gift of play is that it teaches us how to deal with the unexpected—a critically important skill in today's uncertain world.

2. Play activates the entire neocortex

We now know that gene expression (whether a gene is active or not) is affected by many different things in our lives, including our environment and the activities we participate in. Jaak Panksepp, Ph.D., a Professor at the University of Washington studied play in rats earning him the nickname of the "rat tickler."

He found that even a half hour of play affected the activity of many different genes and activated the outer part of the rats' brains known as the neocortex, the area of the brain used in higher functions such as thinking, language and spatial reasoning. We don't know for sure that this happens in humans, but some researchers believe that it probably does.

3. It teaches children to have positive interaction with others

It used to be thought that animal play was simply practice so that they could become more effective hunters. However, Dr. Panksepp's study of play in rats led him to the conclusion that play served an entirely different function: teaching young animals how to interact with others in positive ways. He believed that play helps build pro-social brains.

4. Children who play are often better students

The social skills acquired through play may help children become better students. Research has found that the best predictor of academic performance in the eighth grade was a child's social skills in the third grade. Dr. Pellis notes that "countries where they actually have more recess tend to have higher academic performance than countries where recess is less."

5. Unstructured play gets kids moving

We all worry that our kids are getting too little physical activity as they spend large chunks of their time glued to their electronic devices with only their thumbs getting any exercise. Unstructured play, whether running around in the yard, climbing trees or playing on commercial play structures in schools or public parks, means moving the whole body around.

Physical activity helps children maintain a healthy weight and combats the development of Type 2 diabetes—a condition all too common in American children—by increasing the body's sensitivity to the hormone insulin.

It is tempting in today's busy world for parents and kids to fill every minute of their day with structured activities—ranging from Spanish classes before school to soccer and basketball practice after and a full range of special classes and camps on the weekends and summer vacation. We don't remember to carve out time for unstructured play, time for kids to get together with absolutely nothing planned and no particular goals in mind except having fun.

The growing body of research on the benefits of unstructured play suggests that perhaps we should rethink our priorities.

Not sure where to get started? Here are four People Toy Company products that encourage hours of unstructured play.