It's hard to describe the physical and mental strain you suffer as a Big Brother housemate. Anyone trying to convince me of the fact before my own two months in the Elstree oubliette last year would have been blessed with my most indulgent smile.

Now, I am the one trying to explain to my friends, family and readers just how ruinous the whole thing can be for your nerves. Frayed doesn't even cut it. Minced would be a better description.

From the moment you're told you'll likely make the cut, it's as though you've been crowned at the same time as having your neck pressed onto the chopping block. Months of secrecy, trepidation, excitement and terrible self-doubt. Chatting with friends and thinking about every word you utter, falling asleep and hoping your snoring isn't too infuriating, stuffing your face and trying to look good for the cameras that will very soon be zooming in on your every dribble. And that's before it begins.

There is nothing – absolutely nothing – to prepare you for the feeling as you walk down the infamous luminous stairs to the hollow, faintly springy carpeted floor of the Big Brother house. You are being watched by Dante's rings of reality television. Farthest away are the millions of television viewers. Then the journalists, hoping to use your every misdemeanour as clickbait. Then, of course, the programme-makers, followed by the camera crew peering at you through the silver-foil mirrors and finally, Big Brother himself. A conglomerate brain of all the rings combined, with tentacles tickling their way into your strange little world.

And how they manipulate your every moment. Not always malevolently. If you are ill you are given medicine. If you seem very disturbed or fretful he will talk to you and comfort you. But if you are hopelessly deprived of sleep (I managed at most 4 hours a night, sometimes none at all) then he will wake you every time your eyelids close. If you find calm on your bed, he will close the bedroom for "essential maintenance" and force you to convene with your tormentors. If you are hungry he might lock the storeroom. Warm and the air-con will blow. Peaceful and a task will encourage your 'friends' to tell you exactly why they hate you.

Every single night you go to sleep relieved to still be there but furious to still be there. Every morning you wake, excited that you are in the Big Brother house but genuinely afraid of what is to come. Why, you might reasonably ask, do you care? It's only a silly television programme. No, but it isn't. It's you. You and everything about you is on trial. If you are disliked and punished in that house then it is about your personality and, ultimately, everything you are. It is a mindless and vapid phrase: 'Don't take it personally'. In Big Brother, only the most ignorant lemmings (and I lived with enough of those) could ever think it wasn't personal.

Andy West
Andy West is evicted as the fourth runner-up at the Big Brother Final 2016 at Elstree Studios on July 26, 2016 in Borehamwood, England Getty Images

Big Brother is a constant, unremitting attack on your sense of dignity, autonomy and pride, not to mention your body. My friend Jason Burrill who won Big Brother last summer lost nearly three stones in weight while he was in there (intriguingly others somehow managed to gain almost as much) and I lost only a little less. Both of us, by the final eighth week were left juddering and shaking in constant waves of anxiety. I was on medication for panic attacks for the last three weeks and they continued long after my escape.

And then, the escape which is not an escape at all; rather, it's a rebirth into a world that no longer makes any sense. My ex-fiancé Ed, who entered the house to propose, told me minutes after my eviction that the papers had reported on our relationship, posting pictures for all to see of his dalliances on the gay sex app Grindr. It took a few days but he admitted in the end that he had cheated.

This, combined with the bewildering joy and terror of finding myself a TV personality with no actual work, threw me into a dark maze of depression, drunkenness and fear which was only stayed by the extraordinary support of my new agent Christian Guiltenane, who had taken me on as a client when others wouldn't.

Big Brother did offer me ongoing support with the show's psychologist, but I found myself ignoring much of his eminently sensible advice because what I wanted on eviction was not what my emotional state required. I wanted work, I wanted excitement, I wanted people to know my name, I wanted to be liked, I wanted to have sex and I wanted to sit alone for long periods crying. I wanted to escape from people constantly asking me when the wedding was.

So yes you are, contrary to many reports, offered psychological support following the programme. But the hard truth is that, having watched most of my fellow housemates twist into a horrible downwards vortex of hopeless tragic vanity-driven failure and ignominy, no number of psychologists, therapists or asylums could ever save them from their own egomaniacal delusion. The truth is they don't want help, they want fame. They were bonkers at the start of the show and they're still (most of them anyway) bonkers now. That is why they were great TV.

So I can understand why the current crop of celebrity housemates are already escaping Big Brother's Wasp Factory, for both physical and emotional reasons. It's little wonder Austin Armacost is going spare over his public image. He knows he was popular on the last show and now he's worried he's coming across badly, and that his relationship and various promo-deals might be at risk. How quickly the paranoia sets in. But he'll be fine, as people – I think – can see he's a good bloke. Brandon Block has reportedly suffered from chest pain and RayJ's tooth became unbearable. When you are surrounded by social horror, it's inevitable your body will feel genuine pain.

Austin Armacost asks to leave the Big Brother house on 10 January, 2017 YouTube/Channel 4

Headaches, stomach upsets, muscle-pulls, panic attacks. All are common in the house. The question is, can you endure them?

I will say one thing. In spite of the anguish, I always knew that I would never leave the house unless Emma Willis called me to the baying mob outside on eviction nights. Perhaps that's partly why I stayed in until the final when so many other housemates fell away. I wanted to be there as a test of strength. It's a harder test than I can ever explain, but I'm proud to be one of the few who truly passed it.

Why did I go into the house? Well, what would be the honest answer to that? Let's take a breath. Because...I didn't want to be a news reporter anymore. Because I was angry at the BBC. Because I wanted to be on television as myself rather than a sock puppet. Because I liked the idea of being a TV personality. Because I knew that in spite of my failings – of which there are many – I am a kind, generous, funny, interesting man and that most people I meet like me.

After a dark period, I now feel as though I've found the start of a career that can truly make me happy. In my writing and my TV work I can be myself and be happy. I'm sitting in the Celebrity Big Brother's Bit on the Side green room as I type. For my growing success I'm grateful to Big Brother. It gave me a few lemons but since then it's also helped me squish 'em into lemonade.

Andy West is a writer, presenter and journalist.