A new study adds to evidence that when children spend too many hours on devices, it negatively impacts their mental health.

Researchers tracked the screen time of 4,000 children starting at the age of 9-10 years old and found that by the time they were 13-14 years old those who spent excessive time on cellphones and social media had at least twice the likelihood of developing mental health issues compared to those who spent less time on devices.

"We know that rates of depression, anxiety and suicidal thoughts in kids have increased dramatically in recent years," said Dr. Raviv Berlin of Stamford Health Psychiatry. "42% of high school kids reported feelings of sadness or hopelessness in the past year."

According to the Journal of the American Medical Association, half of teenagers are becoming addicted to their cellphones. Girls are at a higher risk to social media, while boys are more likely to get addicted to video games.

Doctors say children develop better spending quality time outdoors.

"Exploring, navigating outside, playing with friends, connecting with nature," said Dr. Berlin. "They need to be having dinner conversations with family and they need to be growing their appreciation for art, music, sports. Screen time in isolation robs kids of these rich experiences."

Parents should set a limited amount of screen time for young children and watch the content they are exposed to.