Many people with mental problems are too scared to discuss the issue with their bosses because they fear they would be subject to discrimination as a result.
This is according to research conducted by Rethink, which found that 59 per cent of workers polled would feel uncomfortable discussing such things as depression, anxiety or bipolar disorder with their line manager if they were suffering from them.
It was also discovered that 26 per cent of these people would be concerned they may lose their jobs.
Antonia Borneo, policy manager at Rethink - a charity that was established over 30 years ago and aims to give a voice to those affected by mental illness in the UK - said the figures confirm what its members tell it.
She went on to state: "Even when employers have mental health policies in place, line managers often feel ill-equipped to deal with mental health issues among staff."