Retiring and retired police or their relatives are referred for mental health treatment every week, a Northern Ireland medic said.
Psychotherapist Adam Getty works at the Police Rehabilitation and Retraining Trust (PRRT) near Belfast.
The team have a large caseload, he disclosed in a blog post.
He said: "Retirement can be a time of reflection. For police officers reflecting back on their service, the sacrifices, the risks and the losses and reflecting forward into a new and unknown future.
"This can be an emotional time, with simply too much time to think and too much to think about being an unhealthy combination.
"Feelings of isolation from colleagues and even family can compound problems."
More people have taken their own lives in Northern Ireland over the last 20 years than died during the conflict, he said.
Men aged between 40 and 60 are starting to become a bigger proportion.
The cognitive behavioural psychotherapist said depression can trick the brain into having negative thoughts that are not accurate.
"Nobody else could be feeling down, depressed or hopeless" and "It must only be you; nobody could be feeling this way".
Behaviourally it can show itself in such ways as; no longer enjoying the things that you once enjoyed; sleeping too much or too little and avoiding leaving the house.
He added: "Retirement is supposed to be enjoyable, fun and time to start doing all the things you thought about when you were on night shift.
"Officers are reluctant to talk about it as well, as they worry that would be viewed as a sign of "weakness" or you might be seen as a "failure" or less of a person even though it is a normal reaction to often abnormal experiences."
There is still a stigma that it is okay to have a broken bone but as soon as you start to say you are mentally struggling, you are seen as different, he said.
He added: "I and my colleagues have a large caseload with new referrals coming in every week.
"There is a stigma around mental health; I hear it all the time. But, just because you can't see it doesn't mean that it isn't there."