Teachers are increasingly forced to deal with pupils with mental health problems because of shortages in specialist services.
A report, commissioned by the union NASUWT, reveals that classroom control and teachers' job satisfaction are compromised by a lack of support when dealing with pupils' needs.
The report, which will be published next week, is based on interviews with 221 primary, secondary and special needs teachers. It was conducted by researchers at a north London mental health trust and reveals that teachers' lack of specialist training means that they are often unable to diagnose problems.
One teacher said: "When the children are tearful, are frightened to go home, do you see that as a mental health problem? I don't know. Or do you see that as a social problem? Or do you see it as a behavioural problem?"
Instead, they fall back on educational terms, such as "emotional and behavioural difficulties", or rely on rule-breaking as a hint that there may be a problem. Other teachers say that they follow their gut instinct.
The study found that primary schools often fail to pass on relevant information when pupils transfer to secondary.
Most of the teachers interviewed felt that there was a need for trained professionals to deal with mental health problems. School counsellors were cited as an effective means of helping children, but most of the teachers interviewed also spoke about the lack of available counsellors.
They had similar reservations about educational psychologists. The report said that overstretched psychologists now take a hands-off assessment and observation role. "This hands-off approach, coupled with large class sizes that include too many children with special needs, makes it too difficult and time-consuming for teachers to implement strategies that the educational psychologist may suggest," said the report.
Charles Ward, general secretary of the Association of Educational Psychologists said: "We would love to do individual work with children, but we're a shortage profession."
The report also raises teachers' frustrations with child and adolescent mental health services. Schools are not able to refer pupils directly to such services. Instead, they must come via an educational psychologist or doctor.
One teacher quoted in the report said: "Some parents will say, 'Yes, yes, yes, we'll do that,' and never go to the GP." Interviewees argued that mental health professionals should routinely work in schools and liaise with teachers.
Chris Keates, NASUWT general secretary, said: "These problems affect teachers' workloads, and their ability to support pupils. Teachers need trained, qualified people to support them. We would like to see a much more streamlined system of referral."