Many employees in Britain are expected to take on the workload of more than one person and fewer than two-thirds believe the amount of work they are asked to do is reasonable.
The figures, from a survey by Mercer Human Resource Consulting, suggest that many organisations are chronically under-manned and over-stretched.
Only half (55 per cent) the 1,000 people surveyed feel that there are enough people in their department to handle the workload.
"It is hardly surprising that stress is now one of the major causes of long-term sickness absence in the UK," said David Tong, Principal at Mercer.
"As companies continue to cut back costs, there is an increasing expectation that employees will take on additional responsibilities.
"Young professionals have always felt the need to work much longer than the traditional 35-hour week to prove themselves and claw their way up the career ladder - now other employees are expected to follow suit."
Almost four out of 10 workers also feel that the department they work in is not run efficiently, placing them under added pressure as they struggle to compensate for poor processes and work organisation.
Unsurprisingly, fewer than two-thirds of the employees surveyed (65 per cent) say they are able to maintain a healthy balance between their work and personal lives.
"Many organisations claim they offer flexible working arrangements, but most of these schemes are available to only a select group of employees," Tong added.
"By being more adaptable to people's personal circumstances, companies can help to retain a healthier and more engaged workforce."
To make matters worse, only half the respondents believe that their managers understand the problems employees experience in their jobs.
"Often managers are too caught up in day-to-day pressures to listen to their employees. But if staff do not feel their managers support or empathise with them, they are likely to become frustrated and disaffected," Tong pointed out.
"Employee attitude surveys can help uncover problem areas and show line managers where they should be focusing their efforts to improve morale and productivity," he added.