The time police spend waiting to see a psychologist has fallen from 19 weeks to 10 days, the Police Federation for Northern Ireland said.
Stress-related illness takes up a significant proportion of the total days off due to sickness at the PSNI.
Federation chairman Mark Lindsay said the group which represents rank and file officers had put in £1 million of its own members' money to speed up processes and improve resilience.
"Policing is a very high-pressured environment which over an officer's career sees them build up quite traumatic experiences over a long number of years.
"This is all combined with the everyday pressures and stresses and strains that we see.
"There needs to be proper cognisance taken of the impact that this environment has on people's mental health.
"There needs to be investment, not only by us but by the statutory agencies in actually dealing with this in a proper and proactive manner and actually recognising it."
He said the PSNI had introduced some mechanisms but it was all around funding.
"At the minute where the chief constable's budget sits, he has to deliver policing with an ever-reduced budget. Unfortunately this maybe doesn't get the proportion of the budget that it requires.
"They have worked very closely with the Federation to try to fix the problem because they recognise it too."
Improving processes has been responsible for some progress.
The Federation has also used its fund to expand the PSNI's existing contract for mental health services, provide resilience training for new recruits and district officers and enable people to seek help themselves directly.
A total of 1,500 people have been through the programme, which also offers alternative therapies.
Mr Lindsay added: "Instead of someone being absent from work they can speak to a counsellor earlier."
He said some officers who dealt with child or domestic abuse experienced high levels of pressure and stress due to under-resourcing and the nature of their work.