Medical Research Council scientists have discovered a startling number of 11-year-olds with symptoms of physical or psychological problems.
Helen Sweeting and Patrick West of the MRC's medical sociology unit at Glasgow University are carrying out a major study on health and lifestyle trends in 3,000 young people, following them from age 11 to age 16.
Their preliminary findings from pupils in the final year of 140 Strathclyde primary schools reveal that although most children are reasonably healthy, happy and optimistic about the future, more than half said they had had headaches, stomach aches, and colds or flu during the previous month.
Two in five reported irritability and nervousness, and one in three said they had been unhappy or had difficulty sleeping.
"There's an expectation of healthiness among children," Dr Sweeting said. "People say there's no point doing a study because you won't find anything, and the children are too silly to tell you anything anyway."
But the children had been able to deal with a complex questionnaire, and were sophisticated enough to know about psychological problems such as nervousness, and explain how they felt. Twenty per cent reported being lonely outside school at least once a week, 9 per cent were lonely in school, 14 per cent had been teased and 5 per cent bullied.
The researchers found that girls were more likely to be unhappy or nervous than boys. This was directly related to dissatisfaction with their looks and weight, and girls were also more likely to be on diets and to have lower self esteem.
"Boys were concerned with the same kinds of things as girls but to a lesser extent," said Dr Sweeting. "Forty-five per cent of girls were worried about putting on weight, compared to 29 per cent of boys, and 11 per cent were on diets compared to 7 per cent of boys."
Despite the anxieties about weight, the traditional west of Scotland high-fat diet was in evidence, with 47 per cent of children eating chips and 30 per cent eating sausages or burgers daily or most days.
But 80 per cent regularly ate fresh fruit, 99 per cent said they enjoyed sport and exercise, and attitudes towards smoking and drugs were overwhelmingly negative.
The great majority also thought school was worthwhile and enjoyable, and teaching was the second most popular choice for a future career, after football.
"These early findings suggest that although there are aspects of their lives which give rise to considerable concern, the picture is not as gloomy as is often portrayed," Dr West said.