One in five MPs has had mental health problems, a survey has revealed.
The shocking statistic comes from a questionnaire completed anonymously by MPs, peers and parliamentary staff.
Twenty-seven per cent of MPs admitted having a personal experience of mental health problems as did 17 per cent of peers and a well-above-average 45 per cent of staff.
"These findings are an affront to democracy," said the chief executive of mental health charity Rethink, Paul Jenkins.
"MPs and peers need to be free to bring their personal experiences to their vital democratic role. Instead they are being gagged by the prejudice, ignorance and fear surrounding mental illness."
The report, published jointly by the All Party Parliamentary Group on Mental Health, the Royal College of Psychiatrists and several mental health groups, calls on a reform of the law whereby an MP must give up their seat for life if they are sectioned under the Mental Health Act for six months.
Most of the 94 MPs questioned thought this should change.
Mind's chief executive, Paul Farmer, said: "At a time when the government is appealing to employers to be more understanding about mental health issues as part of its aim to get people off benefits and back into workplace, it seems they should be looking to take action closer to home.
"Repealing antiquated rules that ban MPs from returning to work after recovering from a mental health problem would send out a clear message to all employers that discrimination should not be tolerated."
But one in three MPs said an expected hostile reaction from the media would stop them being open about mental health issues.
This is in stark contrast to the example of Norwegian prime minister Kjell Magne Bondevik who publicly disclosed his experience of depression without any serious effect on his popularity. He went on to be re-elected.
"When we invited Mr Bondevik to come to speak to MPs, he was amazed that had he been British he could not have stood for Parliament," said Stand to Reason director Jonathon Naess.
"In a civilised society, people with experience of mental ill-health should not be restricted from being MPs, directors, partners, magistrates and jurors."
The report follows revelations by John Prescott, former deputy prime minister, about his struggle with bulimia earlier in the year, which earned him considerable derision in the media.