Bullying in the workplace is "endemic" in the UK, affecting 80% of employees, the Samaritans charity has warned.
A third of workers say employers turn a blind eye to stress levels
The charity said a third of those it surveyed were so unhappy they had considered leaving their job.
Its research identified young employees as the group most vulnerable to stress, and the least able to discuss concerns with managers or colleagues.
The findings are published as part of the charity's campaign to highlight the importance of mental health at work.
"Job-related stress has a serious and unrecognised impact on the health of the nation and the economy, affecting concentration and efficiency," said Samaritans spokesman Joe Ferns.
"Thirteen million working days were lost to stress, depression and anxiety in 2005 at a staggering cost of £3.7bn to UK plc.
"Positive workplaces are a big factor in keeping everyone emotionally healthy," he added.
The survey spoke to 2,600 adults in the UK and the Republic of Ireland.
Half of those questioned admitted they were worried about the impact stress was having on their health - and the same proportion said they had seen a colleague reduced to tears at work.
A third felt employers ignored the problem, while just under half felt their bosses were prepared to put them under pressure to get as much work out of them as possible, regardless of the consequences.
According to the survey, young employees aged between 18 and 24 found it most difficult to tackle the problem.
In addition, a majority of IT workers, retailers, caterers and engineers interviewed for the research reported feeling unsupported at work. In contrast the majority of people working in health, education, banking and finance said they received "adequate" backing.
The charity has designated 1 February as "Stress Down Day" as part of its efforts to encourage a greater awareness of the importance of good mental health at work.
The TUC backed the findings.
"Workplace bullying can take many forms but it always causes stress and anxiety for victims," said TUC general secretary Brendan Barber.
"If bullies are allowed to dominate a workplace, staff morale and productivity will suffer, so employers have a clear incentive to stop bullying," he added.
Responding to the research, the employers' group the CBI acknowledged that workplace stress was an important issue, but said the Samaritans' findings were significantly out of step with official statistics.
"Workplace bullying should never be tolerated and most employers have policies to prevent and deal with it," said senior policy advisor Marion Seguret.
However, she added: "It is important not to exaggerate the problem - government data shows that less than 4% of employees have experienced bullying in the workplace in the last 2 years."