The long shifts worked by resident doctors are putting them and their patients in danger, warns the organisation representing the doctors.
The New Zealand Resident Doctors Association is undertaking urgent mediation with district health boards and says working up to seven consecutive 10-hour night shifts for 12 days in a row - including day shifts of up to 16 hours - is unsafe.
National secretary Deborah Powell said, after nine months at the bargaining table, it was keen to see a resolution.
"The doctors are dog-tired. We're talking over 110 hours in these stretches.
"They're making mistakes, the residents in a recent survey self-identified 1162 adverse effects on patients as a result of working those hours and 275 acknowledged that they have fallen asleep at the wheel while driving home after one of these stretches."
The rosters caused doctors to be so tired they simply could not do their jobs properly, she said, but boards were not changing their rosters.
"We've been working on this for four years trying to get DHBs locally to change their rostering practices.
"Leaving doctors in this perilous state, it's no longer an option. We've reverted to the bargaining table to say actually we want this done now and we want it done more quickly than this local process is allowing."
Ms Powell said the association acknowledged there had been some successes and were grateful for Tairāwhiti DHB in Gisborne fixing their rosters, and Northland District Health Board changing three out of its five rosters, but other DHBs needed to follow suit.
"Unfortunately, for about two thirds of them there has been no improvement at all and a further 48 of the 144 rosters have only been partially fixed."