Eight out of 10 police officers are displaying signs of depression or anxiety as a result of "doing too much", the chairman of the Police Federation has warned.
Calum Macleod said that cutbacks in police welfare departments had depleted forces' ability to provide enough support and wellbeing resources to their officers, and revealed that some counselling services had been outsourced as a result.
But he said that the solution was still not enough to address the "root causes" of the pressures felt by visible and specialist officers affected and that the number of sessions provided was inadequate.
Efforts to provide counselling for officers were also affected by long NHS waiting lists for mental health provision, Mr Macleod said.
Freedom of Information requests by the Press Association revealed that, in some forces, frontline officers in England and Wales were owed one week worth of rest days.
In Lancashire on September 4, the remaining rest day balances which were outstanding and awaiting re-allocation was 37,010 hours and 31 minutes - this equates to 4,626 rest days, based on them being eight-hour shifts.
On that date, the headcount of frontline staff was 2,675.
Mr Macleod told the Press Association: "The conversation around mental health in policing has become greater in recent years. There is a recognition that police officers are human, that they can be broken and that their mental health is an issue.
"What we're seeing is eight out of 10 officers, in a recent survey, have come back and said they are feeling symptoms of anxiety or depression.
"That is a very startling figure when you look at the amount of police officers in the UK. They need to recuperate to provide the best possible service to the public.
"If officers aren't feeling refreshed and having rest between their shift patterns, what you find is that the situation of their mental health is exasperated."
He added that a reduction in a number of officers on the street has "significant impacts upon the public" and resulted in the workload being stretched out between officers. Around 21,500 fewer officers are on the streets now, than nine years ago, he said.
He said that although measures were being put in place to help officers suffering from poor mental health, it didn't "take away from the fact that the root cause of this is that they are doing too much, with not enough support, with not enough rest".
"What you found at the beginning of the austerity measures is that police forces' welfare departments were cut back. So the ability for forces to provide support for officers going through any medical incident was diminished," he said.
"So the voice was having to be filled - through the NHS. The NHS waiting lists are quite big and you just end up in a vicious cycle."
As a result, counselling has been taken on by external services. But Mr Macleod warned that the "four or five" sessions which forces provide for each officer was not enough.
A Police Federation report on officers' pay and morale last year indicated that over the previous year, a larger proportion of officers said their morale had been "negatively affected by their work-life balance, their health and wellbeing, their workload and responsibilities".
Out of more than 30,500 respondents, roughly 85% said that the way police were treated had a negative effect on their morale, while only 4% said it affected them positively. More than two in three said they did not feel valued.
Mr Macleod said: "The Government is saying we need to do more for less - all that you get for less is less.
"Although we will remain being professional and trying to meet the public demand, that cannot continue. Public safety is being compromised, it needs to have proper resources ploughed into policing."