Emergency departments in NSW hospitals have been described as "far from the best" environment for mental health patients needing support.

There are concerns NSW hospital emergency departments are "far from the best" environment for mental health patients needing treatment and support.

The latest NSW Bureau of Health Information data shows patients with mental health-related issues were more likely to spend more than four hours in an emergency department compared to patients without a mental health issue.

Australia's peak emergency medicine body said Wednesday's report confirms many of its concerns about the treatment of mental health patients.

Australasian College for Emergency Medicine president Simon Judkins said it was unsurprising that mental health patients rated their experiences of care in EDs lower than those without mental problems.

"Hospital emergency departments, without adequate resources and support, are far from the best environments for patients experiencing mental health crisis," Dr Judkins said in a statement.

The report also revealed 10 per cent of mental health patients spent more than 24 hours in emergency departments in southwest Sydney hospitals.

"People presenting to EDs with mental health-related issues waited longer for treatment, spent more time in EDs and reported less positive experiences of care," BHI chief executive Diane Watson said in statement.

About one-quarter of mental health patients were aged between 15 to 24 years, the report found.

NSW Health said that number was "no surprise" given the average onset of most mental health conditions is the early 20s.

"These numbers show our efforts to reduce stigma are making a difference, as increasing numbers of people seeking care may represent an increased willingness to seek treatment," deputy secretary Nigel Lyons said in a statement.

Lifeline 13 11 14

beyondblue 1300 22 4636