Mr Fairoz D'Cruz, 32, quit the teaching service in mid-2014, after teaching for seven years at secondary schools in Singapore.

"Work starts at 7am and does not end when I get home at 6pm," he said. "I have had parents and teachers calling me past midnight. This made my wife unhappy as time with her was taken up by school matters, even on weekends and holidays."

His passion for teaching was renewed only when he moved overseas in 2014, when he taught in Morocco for a year, he said. Now, he teaches biology in Germany at the International School Frankfurt Rhein-Main.

Mr D'Cruz said the experience has opened his eyes "to how much better it can be". "There is constant support and reward for the teacher," he said, adding that there are no calls or e-mails outside school hours.

Among those who left, some become tutors, cashing in on growing demand. Others become career coaches or entrepreneurs.

Madam Roziani Rashid, 39, left teaching eight years ago as she craved for more time with her three children, who were then three, six and seven.

When she was a teacher, she regularly put in 12-hour days - from 7am to 7pm. "If I continued, I know I would have no time for my kids," she said. "I didn't think I would quit teaching, but it was too stressful."

Madam Roziani, who taught science subjects for seven years, now runs a health and wellness business.

Mr Anthony Fok, 32, whose childhood ambition was to be a teacher, taught for four years before leaving in 2012 to pursue his PhD at the National Institute of Education. He now runs a tuition centre.

Former teacher Wynn Khoo, 31, who taught physics and principles of accounts for the last five years, also switched to full-time tutoring this January as it gives him flexibility and allows him more time with his family.

"We have many passionate teachers, but many of them tend to be overworked," he said.

Calvin Yang