"If someone breaks their arm at rugby, of course they get top-quality service. But it's much more than that," Mr Vester said.
"Really, before the students even present with a problem, [the nurse] is checking their physical health and how they are emotionally.
"That person forms a relationship with a student and actually does pick up aspects of things that are happening in that child's life and potential health issues."
The study, commissioned by the Ministry of Health and released this week, follows on from a Youth 12 survey of 8500 students in a random sample of 90 state, integrated and private secondary schools.
It looked at the provision of health services at those schools and found "considerable variability".
Twelve per cent had no health services beyond the minimum requirement of first aid provision.
The other 88 per cent of schools had some level of health service, with the most common model being a visiting health professional.
The lead study author, associate professor Simon Denny, said there was less depression and suicide risk among the students in schools that had higher levels of health services.
Those schools had on-site staff well trained in youth health, with enough time to work with students.
The Prime Minister's youth mental health initiative has extended funding to put school nurses or school-based health services in decile 3 schools, as well as decile 1 and 2.
Mr Ryall said he was sure the Government would consider extending school health funding as part of the youth mental health initiative.