Health professionals seeing children with repeated sore throats, colds, breathing problems, nausea, poor appetite, or school worries should consider bullying as a contributory factor

Professor Wolke's report

Psychosomatic

They were also more likely to make up illnesses to avoid having to go to school.

These children also had more psychosomatic health problems, such as bedwetting, nightmares and poor appetite.

Prof Wolke, writing in the journal Archives of Disease in Childhood, said schools should start looking for signs of bullying if a child repeatedly reported these health problems.

He said: "Health professionals seeing children with repeated sore throats, colds, breathing problems, nausea, poor appetite, or school worries should consider bullying as a contributory factor.

"Pure bullies are healthier children compared to victims and bully/victims suggesting that they have a constitution that allows them to become dominant in inappropriate ways."

He said schools should try and break the bullying/victim cycle as early as possible to help prevent problems growing as the child progresses through school.

Strong dominate

The researchers asked the children about bullying and then asked their parents to compile a health profile.

They found many of those who were bullied were smaller and weaker than those bullying them.

Dr Peter Congdon, director of education at the Gifted Children's Information Centre in Solihull, West Midlands, and a member of the British Psychological Society said the survey's results had been unsurprising.

He said the children's behaviour mirrored that of the animal kingdom where the strong dominate.

"It is not until the children are 11 or 12 that they are really at the age of equality and see another point of view."

But Dr Congdon stressed that although the bullies were physically stronger and suffered less mental stress than their victims they were not mentally stronger.