About 8 percent of full-time medical practitioners took zero days off in the latest month, while 7 percent of night-shift doctors put in more than 80 hours of overtime, a survey showed.

One of the labor ministry’s “thresholds” used to recognize deaths as work-related is working more than 80 hours of overtime a month.

On average, the night-duty doctors worked about 64 hours of overtime for the most recent month, according to the survey conducted by Zenkoku Ishi Union (national union of doctors) and the Japan Federation of Medical Worker’s Unions.

Seventy-eight percent of those doctors said they enter normal shifts without taking a break when their night duties are over, according to the survey results released on Nov. 9.

“The situation is very serious,” said Naoto Ueyama, representative of the Zenkoku Ishi Union. “The total absence of days off poses a major problem for the doctors’ health and for medical safety.”

Seventy-nine percent of the doctors said their working hours are negatively affecting their concentration and judgment ability, with 27 percent saying they have actually experienced a growth in errors, such as entering wrong data on computers.

The survey obtained responses from about 1,800 working doctors through academic societies and local governments between July and September this year. About 1,600 of the responses have been analyzed so far.

About half of the respondents said they would approve new labor regulations, such as setting upper limits on working hours.

However, 57 percent of the respondents said they believe that such reform measures would do little to improve their working conditions.

Many said such measures would cause a shortage of doctors, which would make it difficult to maintain the system for seeing patients.

Others cited the strong tendency against viewing medical practitioners as normal workers.