Stressed ambulance crew workers in Northern Ireland are facing "burnout" and have taken close to 7,000 sick days off in the last year - more than double the figure of five years ago.
Health union Unison has blamed increased attacks on paramedics and chronic staff shortages.
In response to a written question from DUP MLA Gordon Lyons, Health Minister Michelle O'Neill revealed how many working days staff had missed since 2011 due to stress, depression and anxiety.
In 2011/12 the total number of working days lost was 2,462, but there has been a massive rise of more than 4,000 days since then - with 6,845 days lost in 2015/16.
Stress and work-related reasons were the largest concern, with 4,717 days taken off last year compared to 1,913 in 2011/12.
Depression accounted for 1,560 sick days compared to 534 in 2011/12, while anxiety levels in staff saw 568 days taken off, up from just 15 in 2011/12.
Brian Ferguson, regional organiser for Unison, said ambulance workers had become demoralised.
"This is down to stress caused by the increasing abuse of staff when they're getting called out. It's getting worse in terms of the verbal abuse and attacks, as well as staffing levels and increased working levels," he said.
"We want zero tolerance in relation to abuse of staff and a recruitment drive to bring in more staff.
"You're looking at burnout. With the increased shifts staff have to cover you can only go so far."
Mr Ferguson added: "They're not backed up by the Northern Ireland Ambulance Service (NIAS) management team. There's demoralisation with the way NIAS staff aren't being treated with dignity."
NIAS said it took the health of staff seriously.
It said: "We are aware of the stressful environments in which our front line and support staff operate."
A health and wellbeing group has been established by the NI Ambulance Service Trust, with staff representatives and access to counselling services.
The trust also promised a review of its attendance management procedure.
Mr Lyons said it was vital that staff were "protected and given as much support as possible in their role".
He added that the DUP had amended the last Justice Bill so attacks on ambulance crew, police officers and firefighters received the same punishment.
SDLP health spokesman Mark H Durkan MLA said: "This figure is reflective of the huge strain and stress on the Ambulance Service staff, who are heroic. I have received assurances our fleet has been invested in and is state-of-the-art.
"What we can't allow is for the people who drive those ambulances, the really important aspect of the service, to become overworked and overstretched."
In March this year it was reported that 300 attacks had taken place on paramedics in 12 months.
Heather Sharpe, a paramedic with 20 years of experience, said she feared for her life in 2012 after being assaulted while on duty by an 18 stone thug in Newtownabbey.
She was left unable to work, while her attacker escaped punishment.
In February it emerged that the Ambulance Service had failed to meet nearly half of 999 calls in Northern Ireland within the targeted time, with crews responding late to nearly 70 emergency calls every day.