More than 28,000 teaching days were lost across schools in Northern Ireland last year due to teachers taking time off for stress, it has emerged.
A teachers' union said "we are seeing teachers buckle under the stress of trying to cope" and warned that morale was at an "all-time low".
The number was reported by BBC Radio Ulster's Stephen Nolan Show following a Freedom of Information request to the Department of Education.
The release showed that 679 teachers had 28,507 work days off due to stress, depression or stress-related illnesses in the 2016/17 academic year - that represents a substantial increase from 578 teachers in 2012/13 taking 20,478 days off.
Avril Hall Callaghan, general secretary of the Ulster Teachers' Union, said its members had been placed under intense stress.
"We have been highlighting issues surrounding each one of these statistics for some time now, warning parents that it is their children who will bear the brunt," she said.
"Teacher morale is at an all-time low - we are already involved in long-running industrial action over pay and workload. School budgets, too, have been so brutally hacked away that principals simply don't have the cashflow to fund their schools. We've seen 'begging letters' written to parents.
"We are seeing a growing number of children with increasingly complex additional needs feeding into the mainstream, where the funding to support them just isn't available. We are seeing teachers - whose vocation is to educate and nurture - buckle under the stress of trying to cope. Is it any wonder sick leave is up and we are losing our young people from the profession?
"We need a sea change if this downward spiral is to be stemmed. Yet, without a functioning government, what hope do we have of that? It is incumbent on our elected representatives to work together and resolve this issue - and in doing so, give our children, and this country, the future it deserves."
Teaching unions have been in dispute with employers over pay and conditions. The NASUWT staged two single-day strikes, the first in Belfast and Newtownabbey last November, and the second in Londonderry, Strabane, Mid Ulster and Fermanagh in January. And members of INTO staged a separate half-day strike in January.
Last October the five teachers' unions in Northern Ireland walked out of talks with employers over a pay offer of 0% of 2015-16 and 1% for 2016/17.