NHS Fife has seen the biggest increase in stress-related staff absence in Scotland, new figures show.
The equivalent of 27,189 working days were lost at the health board in 2017-18 to conditions such as anxiety, which is up 39% in two years.
Nurses say they are being driven to sickness because staff shortages mean they cannot provide the level of care they want to.
Across the country there has been an 18% rise in sick days relating to stress since 2015-16 to 417,740 in 2017-18, according to data obtained by Scottish Labour from health boards.
Monica Lennon, Scottish Labour’s health spokeswoman, blamed recruitment failures for piling pressure on staff.
“It’s obvious that people working in the NHS are being pushed to the limit, often delivering high levels of care to the detriment of their own health and wellbeing,” the Central Scotland MSP said.
In Tayside, there were 35,565 days lost to stress and related conditions in 2017-18, which is 2.1% up on two years earlier.
RCN Scotland director Theresa Fyffe said: “The personal and professional toll of constantly feeling like you are failing your patients is enormous and must not be underestimated.
“For too long, nursing staff have had to deal with increased demands on their time whilst also battling chronic staff shortages.”
Susan Robertson, from Unite in Dundee, said its members were “worn out trying to cope with increasing numbers of patients while staff numbers are reduced”.
She added that patients were “also suffering because of the pressures on staff and services”.
Dr Annie Ingram, the strategic workforce director at Tayside, said the authority used an online stress management programme to promote wellbeing as part of efforts to support staff.
“We work closely with staff side representatives to tackle the impact of issues that may affect our employees’ mental health and wellbeing,” she added.
A spokesman for Health Secretary Jeane Freeman said the government took the “welfare of hardworking NHS staff very seriously” with boards expected to have “robust policies”.
“But we will take absolutely no lectures from Labour when it comes to staffing,” he added.
“It is the SNP which has delivered record high NHS staff numbers, up by more than 12,000 on the number inherited from Labour.”
NHS Fife was contacted for comment.