It was a year after they were made a minister when the MP had the second breakdown of their political career, and realised they simply had no idea what to do next: “I was so terrified. I didn’t know who to talk to. There didn’t seem to be anybody I could trust.

“A family member told me to take time off. But as a minister if you were to say you needed time off sick, the whips would go, ‘Yeah, fine. We’ll get someone else to do your job.’ It’s often easier to keep your head down and pretend.”

MPs are aware the stresses of their job are not always likely to elicit public sympathy. “Cue the tiniest violin you can find,” as one put it. Another likened expectations to the mantra of the royal family: “Never complain, never explain.”

But while a handful of politicians have openly discussed the mental health toll of their job, the scale of the problem appears far greater. “There are many, many people I know who are at their wit’s end,” one said.

Another was even more despondent: “MPs all start out promising to make a difference. And then we promise to try to make a difference. And then we end up apologising that we haven’t made a difference.

“The longer people are here, most of them start feeling they’re wasting their time, that they are hated, that no one really gives a shit about them. It’s a circle of contempt, cynicism and public loathing. And when people’s morale falls, their ability to behave well often does as well.

“I’m not asking for sympathy, because I chose this mad job. But somebody in here needs to start properly thinking about the mental welfare of the people who, to one extent or another, are absolutely vital in shaping the affairs of state.”

While some MPs such as Steve Baker have gone public about mental health problems, it remains extremely rare for others to follow suit in a system where colleagues are also rivals for a tiny number of frontbench jobs.

Some stresses are inherent, such as being away from home for much of the week, but others appear to be getting worse, including abuse and disdain from the public and the scale and urgency of constituency work.

The MP who had a breakdown calculated that when it happened they were working about 90 hours a week, 50-plus of which were for ministerial duties, with constituency tasks on top.

Dan Jarvis, one of those willing to speak on the record, faces that dual role, as shadow security minister and MP for Barnsley Central.

While he says that being in parliament is “a wonderful privilege” – and the stresses are relative compared with his former career as a soldier – Jarvis said there was “this expectation that as a member of parliament you’ve got a bank of people responding to correspondence on your behalf”.

He added: “The reality is that every single day, my team and myself work incredibly hard even just to try to get across all of the new stuff that comes into my inbox. Of the 300 emails that come in some of them won’t be especially important, but within those 300 emails will be the one about a single mum who is just about to be evicted. If you miss it, the stakes of missing that are very high.”

All this happens within an antiquated, hierarchical and convention-bound environment, which, as one MP put it, “feels like it was designed to make you feel inadequate, that you don’t know enough, that you’re not good enough”.

Labour’s Dawn Butler said that although the demographics of MPs were changing, parliament’s structures appeared built around “a man whose kids are being looked after by someone else. Rules need modernising and bringing into the 21st century – it’s basically designed for Jacob Rees-Mogg.”

Another female MP, who asked not to be named, said ever greater scrutiny, including from the media, could be hugely stressful: “I didn’t eat yesterday, because I had this horrible knot in my stomach about a question from a newspaper. I’ve done nothing wrong, but it’s going to worry me until it’s sorted out.”

During their time as an MP, they said, they had seen counsellors twice, including one period when, “I was so stressed I wasn’t sleeping – I stopped functioning”.

Admitting difficulties was rare, she added: “You have activists who helped get you in parliament asking, ‘What’s it like?’ And it would be almost cruel to tell them, ‘Actually, it’s a bit shit. I’m absolutely shattered.’ You need to maintain a public persona, which can be draining.”

Outside help is available, including parliament’s in-house health and wellbeing service. The Westminster Abbey Institute, which works with institutions around the abbey, also organises drop-in sessions where MPs can discuss worries together and in confidence.

However, its director, Claire Gilbert, said that of all the professions the institute works with, MPs were “the hardest to reach”.

She recalls setting up a mindfulness group for MPs: “They would turn up and say things like, ‘There are nurses in my constituency who might find this really useful’. They couldn’t say, ‘I’m here for myself’. They feel like they can’t show weakness.”

In part this seems to be down to the inherent personalities of people who go into politics. “There are underpinning character traits that make you want to do this job,” the former minister said. “You can call that political drive or you can call it unhappiness in disguise.

“I think a lot of people here feel that they’ve failed. And when people start to feel they fail, even if they haven’t, they start to look for ways to make themselves feel better.”

Asked how MPs can cope in a role with, as one put it, “no job description, no manual”, suggestions included finding colleagues who can be trusted, taking care of your marriage and other family relationships – the 40%-plus divorce rate among MPs from the 2010 intake was mentioned several times – and, above all, having breaks.

One MP said they regularly go for trips not just away from Westminster but outside their constituency, so as to not be recognised.

Another said: “I can name colleagues who think it’s OK to work a six- or six-and-a-half-day week, and those days are crazily long, and will turn up here on Monday and say, ‘I’m really tired’. It’s like: when did you last have 24 hours to yourself? It’s a really unhealthy workplace.

“If you’re a new MP, my strong advice would be book a holiday now – because it won’t happen it you don’t book it now. Have boundaries – be clear about what you will and won’t do, and when. And don’t get sucked into the Westminster bubble.”

In the UK, Samaritans can be contacted on 116 123 or email jo@samaritans.org. You can contact the mental health charity Mind by calling 0300 123 3393 or visiting mind.org.uk