For five years, researchers surveyed almost 2,500 moms in Canada, asking them how much time their toddlers typically spent watching or interacting with screens such as tablets, smartphones, televisions, computers, or other devices on weekdays and weekends. The moms also completed a standard developmental screening questionnaire about their children at 2, 3, and 5 years old.

Here are two main takeaways from the results, published in the journal JAMA Pediatrics:

  • At age 2, the children were on screens for an average of 2.5 hours a day. That went up to more than 3.5 hours a day by age 3. For both age groups, that's significantly more than the 1 hour a day of screen time that the American Academy of Pediatrics (AAP) recommends.
  • The more screen time kids had at ages 2 and 3, the lower their developmental scores at ages 3 and 5. These scores measured communication, motor, problem-solving, and social skills.

The study doesn't prove that screen time causes developmental delays, but it does suggest a correlation between the two. It also adds to a growing body of research that links excessive screen time among kids to a variety of problems, including obesity, sleep issues, unhealthy habits, and social, emotional, and behavioral development delays.

Speaking to CNN, lead study author Sheri Madigan likens screen time to junk food. A little is okay, but too much can have health consequences, she says.

Of course, for busy parents living in a screen-obsessed world, reducing your little one's exposure to these devices is easier said than done. For guidance, check out these tips for managing your kids' screen time. Another helpful resource is the AAP's free tool for developing a family media plan.

Keep in mind that it's not just toddlers who are getting too much screen time. Research by Common Sense Media and the U.S. National Library of Medicine shows that older children and teens are also spending multiple hours a day in front of screens.

As a guide, the AAP recommends the following screen time limits by age:

  • Under 18 months: No screen time, other than video chatting
  • Ages 18 to 24 months: Either no screen time or a limited amount of high-quality programming that you watch with your child.
  • Ages 2 to 5: A maximum of 1 hour a day of high-quality programming that you co-view with your child to help them understand what they're seeing.
  • Ages 6 and up: Consistent screen-time limits, making sure that time spent using digital media doesn't interfere with other important activities such as sleep and exercise.