New York, Dec 3 (IANS): Parents may please take note that the more time teenagers spend on smartphones and other electronic screens, the more likely they are to feel depressed and attempt suicide, according to a new study.

Screen time should be considered a modern-day risk factor for depression and suicide, said study co-author Thomas Joiner, Professor at Florida State University in the US.

The study, published in the journal Clinical Psychological Science, showed that those who focused more on non-screen activities like sports and exercise, talking to friends face to face and doing homework were more likely to be happy.

"There is a concerning relationship between excessive screen time and risk for death by suicide, depression, suicidal ideation and suicidal attempts," said Joiner.

"All of those mental health issues are very serious. I think it's something parents should ponder," Joiner said.

However, parents should not think they need to take away their children's smartphones and other electronic devices, the researchers pointed out.

But limiting screen time to an hour or two a day would put a child into a statistically safe zone.

"It's totally unrealistic and probably not even good to think kids will stop using screens," Joiner said.

"It comes down to moderation. Parents should try to make non-screen activities as attractive as possible because a lot of them are attractive," Joiner added.

According to the US Centers for Disease Control and Prevention (CDC) statistics, the suicide rate increased 31 per cent among teenagers from 2010 to 2015.

A US national survey showed that the number of adolescents reporting symptoms of severe depression rose 33 per cent.

Analysing this data, the study found the rise in mental health problems among teenagers since 2010 in the US coincides with an increase in ownership of cell phones.

In 2012, about half of Americans owned smartphones. By 2015, 92 per cent of teenagers and young adults had one, and their screen time also rose.

The researchers discovered that 48 per cent of the teenagers who spent five or more hours per day on electronic devices reported suicide-related behaviour.

The results clearly showed that teens who spent more time on the devices were more likely to be unhappy, said Professor Jean Twenge of San Diego State University.