Mediation begins today between the Resident Doctors Association and District Health Boards over better hours for doctors.

Junior doctors say they're too exhausted under their current rostering system, which sees them work 12 straight days and seven night shifts in a row.

National Secretary Deborah Powell said they've been bargaining for the past nine months and little progress has been made.

"It really is all down to the District Health Boards, and our position is quite clear. We've got a lot of public support for changing these hours."

She said changes were needed, because "fundamentally, exhausted Doctors means poor care and at times unsafe care for patients.

"As those Doctors drive home they're reporting that they're falling asleep at the wheel," she added.