A third of people struggle to cope at work because of depression, stress or burn out, according to a survey published today.
Some 83% of those affected experience isolation or loneliness as a result, the study found.
The research involving 1,200 people across the UK also found that o nly half of those feeling lonely or isolated had confided in a colleague, yet nearly three quarters (71%) found that discussing their condition with a colleague helped them feel better.
The survey, published by Depression Alliance as part of Depression Awareness Week, reveals the high numbers of people affected by depression at work, and highlights the need for employers to take action to recognise the condition better and to support affected staff.
Also launched today, a new report, Depression in the Workplace in Europe: new insights from business leaders, highlights how several major UK companies including Royal Mail, Barclays and Unilever are tackling depression, by implementing new policies to enable structured support and processes for affected workers.
Tim Munden, vice president HR, Unilever UK, said: "At Unilever we firmly believe that addressing depression through our mental health policies benefits both our business and our employees. We aim for a 10% reduction by 2015 in work-related mental ill-health cases and working days lost to mental ill-health."
Emer O'Neill, chief executive of Depression Alliance, said: "Depression is the biggest mental health challenge among working-age people and often leads to considerable loneliness and isolation at work.
"However, many companies aren't properly equipped to manage employees who suffer from depression so providing support to these individuals in the workplace is essential.
"We have just launched Friends in Need, (www.friendsinneed.co.uk) which provides anyone with depression with a free and easy way to connect, either online or by meeting in groups and taking part in local activities, all of which help stop the feelings of loneliness and isolation."
Depression Awareness Week, organised by Depression Alliance, lasts to next Saturday.
Care and Support Minister, Norman Lamb, said: "I want to build a fairer society so that anyone with a mental health problem such as depression gets the support they need when they need it. That's why we've invested £400 million in improving access to treatment for conditions including depression and anxiety - which support people to stay in work.
"We are looking at ways for mental health and employment services to work more closely together and support people both in, and out, of work in building emotional resilience, developing well-being and getting support for their mental health problems. This is an incredibly important subject and there are some great employers already leading the way, such as BT.
"We've also invested £16 million in the Time to Change programme to help reduce the stigma surrounding mental health and last year we published a guide showing managers how to support employees with mental health problems in the best way possible."
:: TNS Omnibus conducted online research among 1,215 British adults aged 16+. The research was commissioned on behalf of Depression Alliance and conducted between April 10 and 14.
:: 'Depression in the Workplace in Europe: A report featuring new insights from business leaders' is published by the Target Depression in the Workplace Advisory Group, an initiative set up by several large companies to advise and support human resources professionals across Europe on managing depression among employees. The full report and further information can be found at www.targetdepression.com