The new legislation comes into force on the wards in August

A pilot project at Ysbyty Gwynedd in Bangor has been looking at the impact of the rules, which introduce a maximum 58-hour week and guaranteed breaks.

It found more doctors would be needed but they then would be less tired - and that should benefit patients.

The deadline to conform to the legal limits is reached in three days' time.

The move is being brought about as part of a new piece of health and safety legislation called the European Working Time Directive.

This directive will apply to all doctors in training from 1 August.

Dr Gareth Roberts, a junior doctor at Ysbyty Gwynedd, said the biggest change would be patterns of work.

"We are going to be moving from the traditional on-call type system to a shift-based system," he said.

"Clearly, the hope for doctors and patients is that, no matter what time you come in, you will see a doctor who is fresh and alert and isn't worrying when he is going to get the next half-hour of sleep."

Training concerns

Dr Roberts said that, with such a big change in working conditions, there were concerns among medical staff about how it would affect matters such as training.

"One of the worries is if doctors do a lot of night shifts, they will spend less time in the hospital during the day, getting exposure to surgery," he said.

Earlier this month, other BMA research found more newly-trained doctors are opting for a career in general practice rather than hospital medicine.

The BMA said general practice offered more opportunity for flexible working, and a better work-life balance.