Stressed Bay of Plenty principals and teachers say they are experiencing "fatigue" and "frustration" due to their heavy workloads.
It comes after a national survey of teachers revealed workload-related stress for principals and teachers far exceeded that of the general population.
The Ministry of Education said significant investment had been made in improving pay, wellbeing and workload but it recognised there was more to be done.
Results from the New Zealand Education Institute (NZEI) 2020 Health and Wellbeing Survey showed one in five school leaders surveyed nationwide were working more than 60 hours per week during term time.
More than 45 per cent of school leaders surveyed reported they were working more than 55 hours a week. The sheer quantity of work was reported as the biggest source of stress for school leaders.
NZEI Rotorua branch president Jo Collyer said Rotorua teachers were feeling "absolute frustration" about working under difficult conditions.
"We are working so hard, we want the best for our tamariki but we are working under difficult conditions."
The Mamaku School teacher, who has been teaching for 28 years, said it was a "systemic issue" nationwide that was "far bigger than any one school can handle".
"We love our job. I would never do anything else but at the same time something has got to give."
Collyer believed all Bay schools needed a full-time teacher aide in every class and there was also a need for increased classroom release time.
"We have a lot of behaviour issues in our classrooms.
"Getting around all our students in a school day is challenging when you have got particular behaviour needs."
She had also previously experienced burnout when working at other schools.
"I have been in circumstances where the workload has led to sleepless nights worrying about students and meeting the needs of students.
"We don't get a work-life balance."
Western Bay of Plenty Principals' Association president Suzanne Billington said the results "absolutely" reflected what school leaders in the region were facing.
Billington, who is principal at Tauriko School, said it wasn't uncommon for principals to be working up to 70 hours each week.
She expressed concern about heavy workloads and not having enough resources to properly care for students, which was causing ongoing and long-term "fatigue".
There was also a "huge frustration" around not being able to access enough resources, she said.
"That is the bottom line. Everything we are fighting for is for kids, their wellbeing and their success as learners.
"We are just totally under-resourced in education. We have got a large number of students who need support, and the resourcing is just not there."
Principals were often dealing with human resources, managing school property, teaching and learning and various other matters, she said.
During the school holidays, almost half of school leaders surveyed reported to be working more than 25 hours per week.
"Your head never switches off. I deal with stuff in my holidays - and so does every other principal I know."
The report also said school leaders' home lives were suffering as a result of work demands.
Billington said even the school's Hauora strategy - including group exercise sessions, practising mindfulness and cutting down on staff meetings - for staff wellbeing didn't reduce their high workloads.
"If your workload is your workload - that is the reality."
Working nights and on weekends, unfortunately, meant hours spent away from family, she said.
"We are all aware that we need to look after our health, but when you are working those kinds of hours the ongoing thinking doesn't stop. If we had more staffing in schools, then we could cope with this workload."
Oropi School principal Andrew King, who worked about 50-60 hours each week on average, said the survey results were unsurprising.
"I have chosen this job. It is quite an amazing job to have, to lead a school community. But it is just always on your mind, it is very hard to switch off from."
The biggest stress was the quantity of work, he said.
"We are not pacing ourselves - it is too much. "
NZEI president Liam Rutherford said the results underlined the urgent need for more staffing resource in the sector.
"When teachers and principals are overworked this ultimately impacts on tamariki and their learning environment."
He said their independent staffing review, Pūaotanga – being released next month – would detail the extent of the staffing issues in the New Zealand education system.
Ministry of Education deputy secretary, early learning and student achievement, Ellen MacGregor-Reid, said the ministry would continue to work with the teaching workforce to make improvements.
"We value the teaching workforce and recognise there is always more that can be done and we will continue to work with the profession on this."
MacGregor-Reid said in 2019 the ministry agreed to pay $3 billion for school teacher and principal pay rises and added in eight more teacher-only days to be used during term time.
"Since then we've continued to work with NZEI and the PPTA [through an Accord] on workload and wellbeing."
She said the ministry had also made a significant investment in improving pay, wellbeing and workload.
"This includes increasing the number of teachers, additional funding for teacher aides, on-the-ground teacher and student support programmes, and increasing the number of learning support specialists."