Teens in Ontario were surveyed about their use of various electronic screens for the first time in an ongoing study.Teens in Ontario were surveyed about their use of various electronic screens for the first time in an ongoing study. (CBC)

Nearly 10 per cent of Ontario students in Grades 7 to 12 average seven hours a day or more watching TV or using a computer, a new survey suggests.

The report was the first time that "screen time" or sedentary behaviour — the amount of time students spend watching television or using a computer — was measured in the ongoing Ontario Student Drug Use and Health Survey Mental Health and Well-Being Report.

Just under 10 per cent of the respondents, a rate that would translate to 93,000 students provincewide, reported seven hours of more of sedentary behaviour, according to Tuesday's online report from Toronto's Centre for Addiction and Mental Health.

The study does not make any cause-and-effect link between screen time and health issues.

The Canadian Paediatric Society recommends no screen time for children under two years of age and a maximum of two hours for children older than two.

The report also looked at how students rated their physical and mental health. Of the students surveyed, 14 per cent reported poor physical health, up from 8.9 per cent in 1999.

A quarter of respondents were considered overweight or obese based on body mass index calculations, lead investigator Robert Mann, a senior scientist at CAMH, and his colleagues found. That extrapolates to 246,000 students across Ontario.

The proportion of students reporting one or more physical injuries requiring treatment in the past year increased from 35 per cent to 40 per cent between 2003 and 2009.

In terms of mental health, the rate of psychological distress, such as feelings of depression and anxiety, over the decade has stayed largely unchanged at 30 per cent. The number of students who sought mental health care during the past year increased to 24 per cent in 2009 from 12 per cent in 1999.

"Many of these students expressed feelings of unhappiness and experienced loss of sleep," Mann said in a release.

"This percentage represents about 327,000 students — a staggering number — and the rate increases with grade. The good news may be that students seem to be consulting someone for mental health issues in higher numbers than ever before."

The percentage reporting any gambling in 2009, 43 per cent, is lower than the estimated 57 per cent from 2003, when the question was first asked. The percentage of students reporting a gambling problem also decreased over the decade, from seven per cent in 1999 to three per cent last year.

The Ontario-wide survey was a self-administered questionnaire to 9,112 students in class between November 2008 and June 2009. The response rate was 65 per cent.