Of those surveyed who experienced problems with stress last year, 22% said they were too afraid or embarrassed to ask for help.
In the survey of more than 1,100 employees, a quarter felt they were overworked and had a poor work/life balance. Nearly half (48%) agreed that their worries and concerns impacted negatively on their working life, with one in 10 having to take time off work as a result.
Only 20% said their employer was understanding about their anxieties, while 17% said they received no support from their employer despite informing them about their concerns.
Nearly a third (31%) of those surveyed reported having lower concentration levels and lower productivity in 2012.
Paul Avis, marketing director of Canada Life Group, said: "Despite the feel-good effect of the Olympics, over half of employees found 2012 to be more stressful than 2011.
"With a struggling economy and the festive season weighing heavily on people's purses, financial issues were a considerable source of stress.
"It is worrying that problems within the workplace were also a major cause of anxiety last year. Employers should take note that this caused one in 10 of the UK employees we surveyed to take time off work, while many saw a negative effect on their concentration levels and productivity.
"These statistics clearly demonstrate it is in an employer's interest to take issues involving stress seriously.
"An employee should never feel too embarrassed to let their boss know the damaging effect stress is having on their life.
"Now is the time for employers to reassess how they support their workers in terms of stress, making sure that access to Employee Assistance Programmes is well publicised and without stigma."
