Parents instinctively know that too much time plunked in front of the television passively watching the screen is not good for their kids. And of course, the television has competition: computers, laptops, tablets, smart phones.

Is this cause for parental concern?

You bet it is!

Both the AMA and the American Academy of Pediatrics recommend no more than two hours of screen time a day for young children. Babies and toddlers shouldn’t watch screens at all, they say.

The jury is still out on the some of the problems many experts suspect are caused by too much time in front of a screen, but there is firm evidence to support others.

There is an established corollary between a drop-off in homework completion and a television in a child’s bedroom. Yet according recent studies, more than 40 percent of children under the age of eight have them.

Kids who spend more than two hours a day in front of the television or computer are at risk for obesity, irregular sleep habits, and sub-par academics.

They also may have difficulty concentrating. No one knows with certainty if the incidence of attention deficits is caused by too much screen time, or if kids with these problems find respite in front of screens.

Some experts believe behavioral problems, ranging from bullying to being unable to establish friendships, are related to excessive time in front of the television and computer. And many educators and mental health professionals believe kids who play a lot of video games and watch a lot of TV become desensitized to violence.

Some studies have found that children who spent hour upon hour in front of a screen were more than 50 percent more likely to suffer from psychological problems as they grew up.

What About Educational Shows?

There is no evidence that so-called educational programs — even the venerable Sesame Street — benefit toddlers. At their young age, youngsters need direct interaction with adults and other kids. They benefit from conversational give-and-take, creative play, and the quaint practice of being read to from books. And like all children, these tots need lots of physical activity.

Talking, playing and being read to form language. Listening to a disembodied character on a screen is far less effective for this critical development.

Once their language skills are in place -- for most kids after age two -- they can watch television and play video and computer games. They also might like to fool around with apps downloaded by their parents onto tablets and smart phones.

But even so, two hours a day with any of these gadgets should be the limit, say most experts.

Of course there are days when this will be impossible. All parents turn to one screen or another to keep their offspring quiet while they start dinner, take a shower, or deal with a household meltdown. And screens are great in airports, waiting rooms, and restaurants. Nonetheless, it’s inadvisable to make a habit of relying on them to babysit.

Parents to the Rescue

No one knows your kids as well as you do and so it’s up to parents to decide how and when to limit screen time.

Still, there are a few guidelines that educators and others believe help kids navigate a world increasingly dominated by screens.

• First, don’t use the television as “background noise.” Turn it off when no one is actually watching a program.
• Watch TV shows with your kids so that you can talk about them.
• Keep computers in the family room or elsewhere where the family congregates. This discourages kids from logging on to inappropriate sites. And, when the gang is right there, your child may find family activities more enticing than the screen.
• Keep TVs out of kids’ bedrooms.
• Set examples for your kids. Don’t constantly check your email. Forbid texting during dinner and other times. Discuss what you learn from a TV show or news from the Internet to promote conversations.

Overall, no one thinks we should unilaterally ban screens for kids who are older than two or three. They are very much part of life and can be powerful tools. It’s up to every family to decide how best to utilize them—and limit them.