FRIDAY, June 4 (HealthDay News) -- For kids, summertime used to mean days spent at the beach or lake, afternoon bike rides and playing badminton in backyards.

These days, summer is more likely to be lived in the not-so-great indoors, with kids glued to computer screens and televisions with little "human" contact.

The indoor child phenomenon concerns health experts and environmentalists, who worry about the effects on health, development and relationships.

By the time most U.S. children enter kindergarten, they have spent more than 5,000 hours in front of a television, and that is enough time to earn a college degree, according to David Mizejewski, a naturalist with the National Wildlife Federation who uses those scary statistics in the federation's "Be Out There" campaign to get children back outside.

Having kids stay indoors in the summer is the lazy way out, of course. "It's easier for parents to say 'Play video games,' 'Watch a show,'" he said. But all that indoor time isn't healthy or good for development, he added.

Among the health benefits of more outdoor time, according to data gathered by the federation:

• Kids will get the 60 minutes a day of physical activity recommended by the American Academy of Pediatrics to improve physical and mental health.
• Obesity risk will decline -- important since obesity rates have more than doubled in the past two decades.
• Kids may enjoy better distance vision -- at least one study has found this in children who spend more time outdoors than kids who don't.
• Children with attention-deficit symptoms have been found to show improvement when they are exposed to natural settings.

Besides the health benefits, the outdoors provides lessons in socializing and other life skills, said Dr. David Elkind, a professor emeritus of child development at Tufts University and author of The Power of Play.

"One of the consequences of childhood moving indoors is the culture of childhood, passed down for hundreds of years [is lost]," Elkind said. He recalls childhoods of the past, where outdoor play was plentiful, and kids learned to handle their own quarrels, negotiate their turn at games, and have other valuable learning experiences.

Even with that list of benefits, however, it can be difficult to get kids out of the house, Mizejewski and Elkind agreed.

So how to make it happen? "Parents need to make it a priority," Mizejewski said.

Taking back control can make it easier. "Kids don't control how they spend their time," he said. "Adults do."

Parents can also emphasize a balance between indoor and outdoor activities, Elkind said, such as "an hour of screen time, an hour of outdoor play, being with your friends."

The screen time might include a nature show. Mizejewski has hosted on Animal Planet, for instance.

Some adults become convinced that outdoor time is crucial once they hear enough statistics. Today, 8- to 18-year-olds log an average of 53 hours a week using entertainment media, according to a Kaiser Family Foundation study released in January.

Only three of 10 respondents said they had any rules about media use.

The answer isn't to simply tell your kids to go outside, Mizejewski and Elkind agreed.

A child's appreciation of play and the outdoors "has to come from example," Elkind said. "It can't come from preaching. There has to be some adult guidance and direction."

"Parents can carve out an hour in the evening," Mizejewksi said, and plan something outdoors as a family. "You don't have to be an early childhood educator or a naturalist to be able to give your kids these important nature activities," he pointed out.

"Kids need unstructured play time, outside in nature, where they can look under a rock, set their own rules with peers," Mizejewski said.

Even going for a walk is good, he added.

Planting a garden with your kids is another good idea, Mizejewski said. Or just have a camp out in the backyard. "You don't have to get in the car and drive to Yellowstone to have a fun camping experience."

The federation, in fact, is planning the 6th Great American Backyard Campout on June 26, urging people across the country to take part in the one-night event and reconnect with nature.

Parents should also be sensitive to the fact that different children will be attracted to different outdoor options, Elkind said. "Give the kids some choices -- hiking, camping, the aquarium."

More information

To find out more suggestions for helping your child spend more time outdoors, visit the National Wildlife Federation.