The union is to campaign for legislation to protect employees from work-induced stress, with tougher action against employers who give teachers insufficient protection.
Research commissioned by NASUWT suggests one in five teachers suffer from anxiety and depression at a level usually seen in psychiatric out-patients. The number of teachers retiring through ill-health has risen from about 2,000 in 1989 to 5-6,000 last year.
Delegates presented a litany of cases of the consequences of stress caused by workload, bullying bosses and unruly and violent pupils. One said his friend had killed himself on the first day of term. Others spoke of callous disregard from heads and senior staff.
London delegate Steve Luscombe said he had been appalled by the lack of support for his members who had been assaulted. One - so badly hurt she was off for five weeks and developed epilepsy - was sent to hospital in a cab and the managers never asked how she was.
The union argues that bad parenting is part of the problem. General secretary Nigel de Gruchy attacked calls for shorter school holidays as an abdication of parental responsibility.
"If people don't want to spend at least part of their time bringing up their own children, they shouldn't have them," he said. "A disastrous lack of parenting is playing havoc with the behaviour of thousands of youngsters."