IN the first such national survey, health authorities here have found that Singaporean teenagers are by and large a sensible lot who mostly don't smoke because it is harmful, don't engage in sex because of disease and unwanted pregnancies, and who try to eat the required servings of fruit every day.

The survey of 3,844 Secondary One to Four students was conducted by the Health Promotion Board (HPB) between April and August last year.

The survey findings, released by HPB on Friday, found that just four out of every 100 15 and 16-year-olds have had sexual intercourse, a far cry from previous surveys by other groups, which polled 20 out of every 100. Top of the reasons for not having sex was the fear of getting sexually transmitted diseases or HIV, followed by the fear of pregnancy, being too young and upsetting their families.

The survey also found that the number of kids who have tried cigarettes dropped from 26 per cent in 2000, to 19 per cent last year. The percentage who had smoked at least one stick a day in the previous month also dropped from 11 per cent to 9 per cent.

But there were some dark spots among the bright. Of the teens who have had sex, one quarter had engaged in intercourse more than 5 times in the last 12 months.

The median age for having sex was 15, which meant that half of those teens were even younger when they started. And nearly two thirds said they had sex because 'it just happened'.

When it comes to cigarette smoking, the prevalence has remained unchanged from 2000, with 2 per cent of all youths regular smokers. More than half picked up the habit before the age of 12.

Exercise also does not figure high on teens' priorities, with only one out of 5 exercising 30 minutes a day for at least 5 days in the week. Boys were more than twice likely to exercise than girls. They were also more likely to eat the recommended servings of fruit and vegetables a day than girls.

Sugary and deep fried foods are also a big hit, which could have an impact on later health. More than half (52 per cent) have deep fried foods more than twice a week, and 29 per cent have sugar-laden drinks more than once a day.

A key part of the survey, on mental health, is yet to be completed.

In the meantime, teens deal with stress by tuning out the world. The top ways of de-stressing are to listen to music, watch television, play computer games and surf the Internet, ahead of talking to someone about it.

HPB said the survey provides baseline data for any youth health initiative the government may embark on later.