Huge numbers of UK workers are hiding mental health conditions from their employers for fear of it affecting their job, according to Friends Life.
A poll from One Poll for the insurance firm, which surveyed more than 2,000 people, found that more than 50% of all workers believe being open about a common mental health problem would damage their career prospects.
The UK working-age population is more than 38 million, according to the Office for National Statistics.
So more than 19 million workers in the UK could be worried about reporting a common mental health problem to their employers.
The research also revealed that four in ten respondents said they have experienced a common mental health problem such as stress, anxiety, or depression in the last year and had not told their employer.
"These statistics paint a worrying picture of a culture of silence when it comes to mental health," said Andy Briggs, group chief executive of Friends Life.
"Our research shows that there is still much to be done in tackling mental health issues in the workplace.
"Anxiety, stress and depression can affect anybody and employees need help and support so that they are not left feeling vulnerable and demotivated."
Friends Life also examined the causes of stress in the workplace.
The report found that the most common answer was excessive workload followed by frustration with poor management and working long hours.
The research also showed that younger workers appear to be feeling the strain more than their older peers.
Almost two thirds of 18-24 year olds agreed that they had experienced stress, anxiety or depression in the last year.
The numbers gradually decreased across older age groups with just over one third aged 55+ feeling the same way.