A total of 5,045 teachers at public elementary, junior high and high schools across the country took sick leave for psychological problems during the 2014 academic year, according to an Education, Culture, Sports, Science and Technology Ministry survey.

These teachers accounted for 0.55 percent of all teachers at these schools. The total number has been hovering around 5,000 since the 2007 academic year.

Leaves of absence for psychological reasons affect not only the teachers and their families but also schools. As such, local bodies have implemented mental health programs and other measures to help these teachers overcome their difficulties and return to work.

Of the 5,045 teachers, 1,548 are junior high school teachers, accounting for 0.65 percent of all teachers at these schools, 535 are at special-needs schools, (0.64 percent), 2,283 are at elementary schools (0.56 percent), 675 are at high schools (0.36 percent) and four are at other secondary education institutions (0.26 percent).

The largest percentage -- 33 percent -- of the 5,045 teachers took leaves of less than six months, followed by 27 percent who took between six months and less than one year, and the same ratio who were away from school between one year and less than two years.

Of the total, 39 percent returned to work within the 2014 academic year, 44 percent continued to be absent in the following year, while 18 percent resigned.

The large number of teachers who take sick leave due to mental illnesses is largely attributable to their heavy workload. According to a 2013 OECD survey, Japanese junior high school teachers worked an average of 53.9 hours a week, the most of any member country.

Teachers are constantly under pressure to improve their students' academic abilities and are also required to respond to diversifying challenges, such as schoolyard bullying and children who refused to attend classes. Many younger teachers also struggle to deal with complaints made by parents.