The impact of COVID-19 and increased workloads are affecting NSW nurses' mental health and wellbeing, and one in three are planning to quit their jobs in the next year.

A survey of 2300 nurses commissioned by the NSW Nurses and Midwives' Association revealed workers are experiencing burnout, including 15 per cent suffering symptoms of post-traumatic stress at clinical levels.

More than half (58 per cent) plan to leave their current role within five years, 37 per cent plan to go within a year and 22 per cent want to leave the health profession entirely.

Union general secretary Shaye Candish says prevention and early intervention measures must be adopted to combat the growing levels of psychological harm being experienced across the workforce.

"The findings of this report are sobering," she said on Wednesday.

"Unless there's urgent investment in protecting the psychosocial wellbeing and mental health of nurses and midwives, they will continue to be injured and leave, which will compound staffing shortfalls even further.

"Ensuring adequate staffing and skill mix, improved reporting of workplace psychosocial hazards, and increased risk mitigation measures to address occupational violence are some of the prevention measures we need implemented."

The union also wants an overhaul of the current employee assistance program to better support staff following traumatic incidents.

The report found better pay, better workplace support and reduced workloads were the top-three retention measures that could encourage nurses to stay.

Early career nurses and midwives were identified as the most vulnerable as they were asked to do double shifts and work outside their areas of expertise more often.

Assistant general secretary Michael Whaites said the issues identified were affecting everywhere from major tertiary hospitals in metropolitan areas to remote and regional health facilities.

"Patient care in these working conditions is being compromised and that is taking a significant toll on nurses and midwives," he said.

"This report is an indictment on the lack of intervention by the Perrottet government. There is ample evidence that shows working under these conditions is psychologically damaging nurses and midwives."

Opposition health spokesman Ryan Park said hospitals in NSW had been overwhelmed, under-resourced and severely neglected over the last decade.

"The mass exodus of nursing staff from our hospitals is yet another symptom of the NSW Liberals' health crisis," he said.