Almost 300 doctors working at public hospitals across the country have reported falling asleep at the wheel on their drive home from work.
The statistic comes from a survey conducted by the New Zealand Resident Doctors' Association (NZRDA) of its members, and also revealed more than 1000 doctors reported they'd made a mistake that affected a patient because they were tired.
All 3600 members of the NZRDA took the survey asking for their experiences over the past year.
The NZRDA is calling for the number of consecutive 10-hour night shifts to be reduced from seven to four, and the number of consecutive day shifts to be reduced from 12 to 10.
It says doctors will often work 16-hour days up to 12 days in a row.
National resident doctors' advocate Dr Deborah Powell says they've been bargaining with district health boards for nine months but have "hit a brick wall".
"The lack of concern for either the doctor's own health and safety, let alone the impact fatigue is having on the patients these tired doctors care for, is astounding," Dr Powell says.
The NZRDA has been working with district health boards for four years to get safer working hours for resident doctors, but went to formal bargaining in December after failing to make change at a local DHB level.
It has made some headway, with 13 of the 150 rosters nationwide meeting the NZRDA's requests, but Dr Powell says there's still a long way to go.
"The DHB's preference is to continue discussing rosters at a local level but if there is no agreement to change, the status quo remains."
The NZRDA has requested urgent mediation, and Dr Powell says if that fails to make change, strike action could be on the table.
But she says getting resident doctors to take union action for better working hours was the last resort.
"I'd be gutted if it came to that."
Labour's health spokeswoman Annette King says it's not good enough.
"You cannot have people who are working such long hours that they are endangering themselves and others just returning to their homes."
"Stress, burnout, long hours, a lack of relief for their work - that is a dangerous situation."
She said the refusal to hire more doctors to allow for better working hours is a result of the DHBs struggling to cover their costs.
"So they will be doing everything they can to keep costs down but it should not be at the cost of patients, or those who provide the service to patients."
She says one of the things New Zealand prides itself is on high quality health services.
"Having accidents and mistakes is not what the public expect at their public hospitals."