Figures obtained under Freedom of Information laws also show more than 2,200 officers had time off work due to mental health issues.
Opposition politicians accused the Scottish Government of failing to provide officers and staff with enough support.
Figures uncovered by the Liberal Democrats show 166,580 officer and staff days have been lost to psychological disorders since April 2019.
The number of days lost rose between 2019/20 and the past financial year.
Meanwhile, the Scottish Conservatives released figures showing 2,235 officers had time off work in the last two-and-a-half years, while 68 took early retirement on grounds that included mental health.
Liberal Democrat justice spokesman Liam McArthur said: “These figures show the brutal toll that mental ill health is taking on the national force. The mental health of officers and staff can no longer be sidelined.
“Police officers are often the ones to assist us in our moments of greatest need, yet the Scottish Government has failed to provide officers and staff with the support they need to manage their own mental health."
Scottish Tory MSP Maurice Golden said: “It’s deeply concerning, but not entirely surprising, that such a high proportion of police officers are suffering from mental health difficulties."
David Hamilton, chair of the Scottish Police Federation, said the figures "support the findings of recent academic research that showed 45 per cent of officers were feeling burnt out".
However, he warned it was "just the tip of the iceberg".
Deputy Chief Constable Fiona Taylor said: "The safety and wellbeing of officers and staff and their families is a priority for Police Scotland and we have a range of mechanisms to support our people, including an employee assistance programme, a wellbeing champion network, post trauma assessment and mental fitness training.
“We have a duty and an opportunity to build and maintain a service and culture founded on our values to improve the experiences of our people.
"Police Scotland is determined to continue to drive improvements to support our people and provide them with the tools they need to do their job.”
A Scottish Government spokesman said: “We continue to support initiatives being undertaken by the Chief Constable to ensure police officers and staff are physically and mentally healthy at a time when Scotland needs its frontline emergency workers more than ever.
“Officers and staff can access a range of services to care for their physical and mental health through Police Scotland’s Your Wellbeing Matters programme, which includes occupational health, employee assistance and the Trauma Risk Management programme.
“Police Scotland were also one of the first police services in the UK to implement mental health and suicide intervention training for all officers, up to and including the rank of Inspector. This benefits the police workforce as well as the public they serve."
The spokesman said police officer numbers “have been maintained and are favourable relative to elsewhere in the UK”, adding: “The 2022/23 Scottish Budget includes £188 million of additional investment – a 7 per cent increase – recognising the vital role of emergency services and the justice sector during the pandemic.”