Stressed and over-worked teachers are increasingly turning to prescription drugs and alcohol to cope with the job, a teaching union has said.
The NASUWT uncovered the "shocking" findings after carrying out its annual Big Question survey of members, revealing that 7% had "increased their reliance on prescription drugs".
Teachers have also turned to antidepressants to help them shoulder their career burdens, with 10% saying they had gone to their doctor for medication.
In the online snapshot of 5,098 responses, 22% of those asked reported drinking more to manage work-related stresses.
Nearly half said they had seen a GP in the past year as a result of physical or mental health problems brought on from working in classrooms, and 2% admitted having self-harmed.
The NASUWT has now called for more support from employers and the Government to help teachers as it puts a motion on the issue to a members' vote at its annual conference in Birmingham.
Other findings revealed that 14% of teachers had undergone counselling, and 5% had been admitted to hospital.
About three-quarters, or 79%, of respondents reported feeling anxious about work, 86% reported having sleepless nights, and 73% said they had suffered from low energy levels.
At the other end of the spectrum, nearly a fifth of teachers (21%) said they had boosted their use of caffeine and 5% admitted increasing their tobacco intake to cope.
A third of teachers said they had suffered poor health as a result of work.
Teachers are debating a motion on Saturday calling on members to condemn the Government and employers "for their inaction on tackling excessive workloads, which is reported as the major cause of stress".
The union is also highlighting what it has called "the impact of unsustainable levels of teacher workload", and wants measures taken to improve support for members in the workplace.
Chris Keates, NASUWT general secretary, said: "Yet again we have shocking figures about the toll the job is taking on the health and well-being of teachers and school leaders.
"It is unacceptable that given the increasing scale of the problem, there is still no sign of either employers or the Government taking any effective action to address this.
"Instead of offering support, in far too many cases we see employers introducing punitive and callous sickness absence policies.
"High quality education cannot be delivered by stressed and anxious teachers."
Here are a selection of responses from teachers who took the survey on their experiences of work-related mental health issues:
:: "Now taking antidepressants. I feel undervalued and unable to trust work colleagues. Stress levels have increased which has impacted upon my interaction with students and the quality of my teaching. I do not enjoy being in my current school and am seriously considering leaving the profession."
:: "Extreme excessive workload resulted in a breakdown. I was off work for six months. Now on maternity. Don't know how I will cope with pressures when I return. Considering leaving teaching. It is not a job that you can do with a young family."
:: "Suffered from depression, anxiety and stress and therefore haven't been able to deliver as effective teaching or feel happy in my job. The demands of the job and the workload combined with bullying in the workplace has been the cause."
:: "Overly tired, poor sleep patterns, no quality time with family, constant worry, heavy work load 70-80 hours per week, irritable and less patient."
:: "I suffer from anxiety brought on by not having enough time to do all the work that has been forced upon me, I am depressed as I no longer have any kind of social life."
:: "On tablets for depression and anxiety. Constantly exhausted. Normal 10 or 11-hour day in school then work at home."
:: "I have developed anxiety as a direct result of the increased workload and the constant change to the curriculum and assessment procedures. I am currently receiving counselling and I will be having cognitive behavioural therapy as well."
:: "Higher dosage of anti-depressants prescribed just to get through the day. Love the pupils but my senior management team are bullies and manipulate staff."
:: "Suffering anxiety and stress. Currently taking antidepressants to overcome depression, brought on by the pressures of the workload and job."
:: "Now on medication to help cope with the stress as became depressed with anxiety issues."
A Department for Education spokesman said: "We know unnecessary workload is one of the biggest frustrations for teachers.
"That's why we set up three review groups to address the key concerns that were raised through the Workload Challenge.
"We are working with the profession and education experts to take action on the root causes of teacher workload, including through the first biennial teacher workload survey and looking in depth at the three biggest concerns teachers have raised - marking, planning and resources, and data management.
"We trust heads, governors and academy trusts to plan their staffing and make sure teachers and staff have the support they need."