Shy children could be diagnosed with mental disorders, if new guidelines being developed in America are given the green light.
Under the new procedures to be published in 2013 - which could be adopted here after being implemented in the US, the Association of Educational Psychologists has warned - children with a number of common problems could find themselves diagnosed with a mental disorder.
For example, quiet children could be diagnosed with "social anxiety disorder", those who become withdrawn following a bereavement could be classed as having a "depressive disorder", and those who talk back to adults may get diagnosed with "oppositional defiant disorder.
The fear for many psychologists is that children experiencing these symptoms may then have to be treated - possibly with drugs - rather than receiving support or therapy.
Speaking at the TUC congress on Wednesday - where psychologists called for a national review of the use of drugs such as Ritalin and Prozac on school children and further research into their long-term effects - Kate Fallon, general secretary of the Association of Educational Psychologists, said: "Behaviours develop over a long period of time, often with a range of complex causes; we can't 'cure' the behaviours we don't like with a quick fix of medicine. They usually require careful management by all the adults around the child.
"In 2013 we're expecting new criteria for the definition of mental illness to be adopted here in the UK. These criteria will lead to many more children being diagnosed as mentally ill, based on reports of their behaviours.
"A shy child could be diagnosed with social anxiety; a sad or temporarily withdrawn child could be diagnosed with depression.
"These are conditions which are also likely to be treated with medication - and under these circumstances, Congress, we will be putting potent drugs into children with little or no understanding of what it will lead to.
"In a society that wants quick results using drugs to improve behaviour is very tempting. But there can be other ways of improving children's behaviour which typically involve time and energy from people."