Teachers' stress leave increased by at least 14 per cent in Wales over the last two years, new research claims.
Figures obtained by the Welsh Conservatives said teachers in the principality needed over 60,000 days away from the classroom due to stress in 2009/10.
Of 14 local authorities who responded to the Tories' Freedom of Information Request, the total amount of days taken off increased from 20,968 in 2009 to 24,079 in 2010.
Pembrokeshire saw the largest rise - from 423 days in 2009 to 1,656 in 2010.
Angela Burns, shadow minister for education, said the figures highlighted the "hidden problems" facing teachers and the education system as a whole.
She said: "It's very difficult to comprehend just how vast an issue this has been for a large proportion of our teaching staff - and the inevitable question is why?
"Strain and pressure serious enough to keep one teacher at home for a single day deserves attention. The loss of tens of thousands of days for many more teachers is an urgent issue that should be identified by the minister and dealt with as a matter of priority."
The Welsh Government said teachers experiencing stress were able to contact the Teacher Support Line Cymru for specialist advice and support.
A spokesman added: "We have taken a number of steps to enable teachers to focus on their core role of leading teaching and learning.
"Our 20-point plan to drive school improvement is designed to provide support to teachers through high-quality development opportunities and resources. We also ensure those schools working in the most challenging circumstances are provided with targeted support through the local authority consortia."