One in three staff at East Lancashire Hospitals reported stress-related illnesses last year, new data shows.
Healthcare experts say the figures indicate an "alarming downturn" in the well-being of healthcare workers.
The 2018 NHS Staff Survey revealed that 34% of workers at the East Lancashire Hospitals NHS Trust had felt unwell due to work-related stress over the last 12 months.
In addition, half the respondents admitted they had felt pressured into turning up at work during the last three months despite feeling too unwell to cope.
The survey, which received 3,655 responses from East Lancashire Hospitals employees, also asked staff about their experience of working at the trust. The majority of staff were working overtime, with 65% saying they worked extra unpaid hours on a weekly basis.
A quarter of respondents said they had been verbally abused or bullied by patients or members of the public, while 12% had faced physical violence.
The results also revealed that one in four staff had been verbally abused or bullied by fellow members of staff.
Lee Barnes, Head Of Staff Health Well Being and Engagement for East Lancashire Hospitals NHS Trust, said: “It’s important to acknowledge that the large majority of our staff are happy and confident at work.
In the 2018 NHS Staff Survey, staff rate the Trust higher than ever - and well above the national average - for staff health and wellbeing, supportive management, staff morale, and having a safe environment against bullying harassment and violence.
“However, despite a growing workforce, NHS staff are under real pressure as the number and complexity of the patients we care for continues to increase.
“Stress experienced by our employees is an issue we’re well aware of, and one we’re tackling head on. Our Health and Wellbeing Strategy includes a number of ongoing initiatives which are being successful in providing a supportive workplace culture.
“But there’s more to be done and we constantly talk to and listen to staff so that we fully understand the pressures they face and the actions needed to help them.”
Across England, four out of 10 NHS workers reported feeling unwell due to stress in 2018 - the highest level in five years.
Unison's head of health Sara Gorton said government ministers were not paying enough attention to growing problems within the NHS.
She added: "With so few staff, it's no wonder the pressures of working in the NHS are making so many health workers ill."
Neil Churchill, director of patient experience at NHS England, said: "Whilst there are a number of positives in this year's survey, it is also clear that local employers can do more to improve.
"We would expect all trusts to listen to the results from their staff survey and take appropriate action."