"In the case of hospital specialists, we have a 50 per cent burnout rate"
Patients are put at risk when a tired doctor works through fatigue, said Powell.
"DHBs should not be encouraging their staff to get more tired than what they are. They should be taking responsibility for ensuring that they're not getting as tired in the first place."
The DHB removed the tweet this afternoon and in a statement said it didn't condone people working past their limits.
"MidCentral DHB has for many years posted to its social media accounts a series of inspirational "Motivational Monday" messages and these have been well received by followers.
"Although the intention was to be positive, we can see how the message could be taken another way. We do not condone people working when tired or past their limit and apologise to anybody who was offended."
It said the communications staff would check postings thoroughly in future.
Doctor after 16 hour shift - tried to insert a line 15 times. Doctor who was fresh, first time. Stop when you are tired.
The tweet prompted people to share stories of their own encounters with tired doctors.
"Doctor after 16 hour shift - tried to insert a line 15 times. Doctor who was fresh, first time," wrote JD Ward.
"This culture is guaranteed to increase burnout... it flies in the face of common sense and basic humanity," wrote University of Auckland nursing lecturer Dr Jacquie Kidd.