An education leader has hit out at a "surveillance" culture in the classroom that he said is hindering teachers' lives.
NASUWT union president Dan McCarthy said teaching had "become more stressful" in recent years, highlighting increased levels of "observation".
Addressing the union's annual conference in Birmingham, Mr McCarthy - an English teacher from Ashingdon in Essex - said constant monitoring added another pressure to those already weighed down by workload.
He said: "Intrinsically, teaching is a stressful profession, but it has become more stressful as the challenges of poverty and inequality have worsened.
"But, instead of supporting teachers, teachers are being subject to more monitoring and more 'surveillance' - surveillance that is punitive and crushing.
"Support programmes designed not to support but to crush, surveillance programmes designed to dismiss teachers on the basis of competency rather than redundancy because the cost to the school is cheaper.
"What of the human cost? I have been told by colleagues that they are not just thinking of quitting teaching but that they have considered taking their own lives."
Mr McCarthy, who turns 65 on Saturday, said he had experienced being recommended for observation less than a month after receiving an "outstanding" report - something he refused to do.
He said such frequent observations had a negative impact on teachers' mental health.