More than a third of absence among head teachers is due to work-related stress, according to a head's association.
Reforms "will crumble" warn head teachers
The National Association of Head Teachers said a survey involving 1,800 schools showed a rise in stress cases.
Its leaders voiced "extreme concern" and said ministers' education reforms would "crumble to dust" unless the matter was addressed.
The association said figures showed 38% of all absence among heads was due to work-related stress.
This represented a rise of 26% on last year, it said.
A spokesperson for the NAHT said: "We will not be able to attain the high standards of education that both government and school leaders desire unless the extremely grave situation of overworked, anxious head teachers still in the system is addressed."
A spokesperson for the Department for Education and Skills said: "No government has done more to support heads because we recognise the challenges and responsibility that the job brings.
"We have increased pay to reward heads for the jobs they do, introduced key reforms to help them manage workloads better and brought changes to promote leadership so they have the skills to cope.
"Recognition of the job has also improved."
The spokesperson said the maximum head teachers can now be paid had risen by more than 35% from £56,676 in 1997 to £93,297 now with nearly £100,000 available in inner London.
Last year a survey suggested a third of sick leave taken by classroom teachers was due to work-related stress.