Working shifts of more than 12 hours is linked to a higher risk of burnout, job dissatisfaction and intention to quit among hospital nurses in a number of European countries, including Ireland.
A new study runs counter to the perceived value among both nurses and employers of working longer shifts. It is a growing practice in Ireland, England and Poland, said the research.
The 12-country study said job satisfaction and burnout were global concerns in the nursing workforce because of the potential impact they have not only on the quality and safety of patient care, but also on retention.
And nursing shifts have been getting longer, spurred by the view that they boost efficiency and productivity, while also offering increased flexibility and more full days off work.
But these extended working patterns have not been comprehensively assessed, said the researchers from the University of Southampton.
They surveyed 31,627 registered hospital nurses, generating a response rate of 62pc.
They excluded those in intensive or long-term care units in 488 hospitals in Ireland, Belgium, England, Finland, Germany, Greece, the Netherlands, Norway, Poland, Spain, Switzerland and Sweden between 2009 and 2010.
The survey included a total of 118 questions relating to the demands and experience of the job itself, the most recent shift worked and personal details.
Burnout was assessed, using an internationally validated three-dimensional measure (MBI), and participants were asked directly about their levels of job satisfaction and intentions to leave.
The average age of the respondents was 38 and most of them were women. Almost two thirds worked in hi-tech and/or teaching hospitals.
Over half (57pc) worked in medical units; the remainder worked in surgical units.
The most common shift length was eight or fewer hours; almost a third worked 8-10 hours; 4pc clocked up 10 to 12 hours. Some 14pc worked 12-13 hours. Just 1pc put in more than 13 hours.
But shifts of more than 12 hours were more common in certain countries. They were worked by 39pc in England, 79pc in Ireland, and 99pc in Poland.
And more than one in four of the entire sample (27pc) had worked overtime on their last shift.
Around one in four reported high emotional exhaustion, while 10pc said they experienced high depersonalisation and 17pc low personal accomplishment - the three dimensions of burnout.
Around one in four expressed dissatisfaction with their job; a similar proportion were equally dissatisfied with their work schedule flexibility and a third said they planned to leave their current job.
The analysis of the responses showed that shift length of more than 12 hours was associated with greater levels of burnout in all three dimensions: job dissatisfaction, working schedule dissatisfaction and intention to leave.
For example, job dissatisfaction rose to 40pc among those clocking up shifts of 12 hours or more, compared with those working shifts of eight hours or less, while the intention to leave rose to 31pc.
Working eight-hour shifts was linked to poorer job satisfaction while doing overtime led to a range of discontent.
While this was an observational study with no definite conclusions, the authors said the findings posed substantial questions for managers.
Employee satisfaction is a "robust predictor" that the member of staff will stay in the job. It can also lead to a heightened risk of mistakes and absenteeism.