A drop in violence in hospital emergency rooms is being put down to under-reporting, rather than a change in patients' behaviour.
Findings published in the NZ Medical Journal on Friday show hospital staff are constantly exposed to aggression.
"This includes verbal threats and harassment that have become seen as a normal part of the work environment, and in many cases there is a failure to report the full extent of aggression that occurs," nurse researcher Sandra Robinson says.
The study was done at Christchurch Hospital, using data collected in May 2014, but Ms Richardson says the findings are applicable to every emergency department in the country.
Staff were encouraged to report any incidents, no matter how minor. In that month, there were 7,896 patient presentations and 107 reports of violence or threats - compared to only 29 reports for the entirety of 2013.
Incidents included patients "with dementia lashing out', "verbally abused and hit in face", "pinched on breast", "pills spat in face" and "water tipped over myself".
"You wouldn't work in a bank, you wouldn't work in a supermarket and accept people swearing at you, making humiliating remarks, coming up with sexual innuendo - and we're not just talking once or twice a day."
Ms Richardson says staff are often reluctant to report violence, as they believe nothing will change.
She says there are a few things that could address the issue.
"What are the reasons that cause people to behave that way? What are the things we could teach staff to make them more resilient? What are the policy changes we could do at an organisational level?"