The HSE has confirmed some doctors are being asked to work 24-hour shifts during the coronavirus pandemic.
It says the practice pre-dates Covid, but that some hospitals may have expanded working hours to deal with current requirements.
The executive says rosters may involve a doctor being on-call for 24 hours, and that it should be designed in line with EU regulations.
The European Working Time Directive states every worker should get a minimum of 11 hours rest in a 24 hour period.
Dr John McFarlane, from the Irish Medical Organisation, says the practice is inappropriate. and errors become more likely.
"The European Working Time Directive should be respected in terms of, 13 hours is supposed to the maximum working shift.
"After that performance drops off and people are more liable to make errors.
"24-hour shifts are too long in terms of both doctor wellbeing and patient safety," said Dr McFarlane