A 'toxic' mix of factors and inadequate funding is forcing mental health workers to burn out and leave the profession.

That's from the chief executive of the mental health foundation.

Shaun Robinson said it is not at all surprising that an Auckland acute mental health unit is closing five beds due to a lack of staff.

He said a mix of growing poverty, housing issues, domestic violence and methamphetamine are driving demand for services.

Robinson said mental health workers are being squeezed by severe pressure and inadequate funding.

"It's kind of a toxic mix of demand and need at a time when resources have been become less and less adequate - the staff are really caught where the hammer hits then anvil on that."

He said the demand for mental health services has increased 70 percent in the last 10 years, while the funding has not increased nearly that much.

"Essentially the pressure on staff across pretty much the whole country is due to a gradual grind down of of the funding available to meet demand."