A typical night in room 25 goes something like this: you are woken for the first time at 3AM, when the last partying backpackers come to bed. The stairs that lead into the room are entirely hollow and have been lined with plastic by some sadist, so anyone who climbs them sounds like they're stomping up a mountain of old body-bags. Behind them, the automatic door-closer slams with the force of a medieval trebuchet.

At 4.30AM, a series of alarms jolt you awake. The early risers climb down from the rows of silver bunk beds and creep out of the room, wearing high-vis overalls. The dorm smells sweaty and damp, like an unwashed PE kit. Orange light seeps through the single window at the far end.

At 5AM, the man in the next bunk starts to get dressed, a process that seems to require him to repeatedly smash a metal belt buckle into the floorboards by your head. From the neighbouring bed you can hear gentle rubbing accompanied by soft sighs, the sound of either satisfactory itching or furtive masturbation.

At 6.45am, someone opposite begins speaking on the phone in French. "Oui," they say. "Oui. Oui, oui, oui." You try to cover your ears with your pillow, but it is as thick and as noise-cancelling as a cheap slice of ham.

By 7AM, your French neighbour has expressed agreement over 40 times.

At 7.11AM, someone with a Midlands accent shouts: "Shut the fuck up, mate, people are trying to sleep."

At 7.12AM, the phone conversation ends.

At 8AM, you wake again with a start. An air raid siren is sounding. You jump out of bed in a panic to discover the grey haired man at the end of the row is gently snoring through his Cold War alarm tone.

At 10AM you arrive at work with bloodshot eyes and wild hair. Your eight-year-old student looks at you for a moment and says, "Why do you look so tired, Ed? Why do you look so sad?"

I had moved into the No.8 Hostel in Willesden, north-west London, where I was staying in a 20-person dorm. There were a number of reasons why this was a terrible idea. I am not a teenager. I'm not on my gap year. I'm a very light sleeper. I have a job. And I already live in London.

I've also had a string of hellish experiences in hostels. I was dumped over Skype in a hostel. A malfunctioning toilet squirted liquid sewage into my rucksack. I had to sit and listen as a Canadian barman described Ace Ventura: When Nature Calls as "the best fuckin' film of all time". So why was I moving into a hostel in my hometown?

The answer was rent. A night in a backpacker hostel in London costs as little as £8, which is what I'd usually pay for two pints or one season of Murder She Wrote on DVD. It's also around half the price of my matchbox-sized room in Tulse Hill.

And, as it turns out, living in a hostel to save on rent is not a unique idea. While most of the residents of No.8 are backpackers from overseas, a significant minority are living there on a permanent basis while working in London.

Jordy, 25, an Australian teacher living at the hostel while she looks for work in London

The backpackers tend to be younger. They're visiting for a holiday or staying temporarily while they look for more permanent accommodation. When I spoke to them, the consensus seemed to be that No.8 was a good choice: clean, sociable and very cheap.

Colm, an Irish carpenter in his early twenties, was about to move out into a house in Neasden. But he'd enjoyed staying in the hostel: "There are no scum here," he said. What do you mean by scum? He hesitated. "No cunts."

Giulia, an 18-year-old student from Italy, had extended her trip to London after befriending a group in the hostel. Since then, she'd experienced many wild and crazy things. "Like, once my friend passed out drunk downstairs. I made him a pizza, but then it sat there in the kitchen for two hours," she said. "The reason was, he had passed out again outside the toilet!" What did she think of the permanent residents? She paused and thought. "Everyone here is strange. I was normal, but now I am also getting stranger."

The long-term guests are older, in their late thirties and forties. They come from the UK or elsewhere in the EU – job insecurity or low pay mean they're unable to save up for a deposit. For a full-time minimum-wage worker, even £78 a week for a hostel dorm bed represents over a third of their post-tax income – a level that can threaten your ability to meet other basic needs.

There were definite signs that the long-term residents had been affected. One morning, I met a man in the kitchen sporting grubby combat trousers and a pigtail. I nodded at him and he gave a phlegmy chuckle. "How was your weekend?" I asked, looking for something to say.

He furrowed his brow. "No, no, weekend," he said, with a definitive jab of his thumb. "Today weekend. Today Saturday."

It was a Monday.

Przemek

Przemek, another longstanding resident, is a slender man with light grey hair. He seemed severe – on my first day I gave him a friendly smile and he looked back as if I'd tried to punch him in the throat – but in conversation it turned out that a raucous laugh frequently breaks through his stoic expression.

From Poznań in Poland, he had lived in London for four years, working in various temporary jobs and sending money back home. His daughter was born around the time he left for the UK. "This is not good for your kids. It's difficult keep relationship with your wife. Over longer times it's impossible. You can't live like that," he said.

He had lived in hostels throughout 2015 and was now into his fourth month in No.8 while he looked for work. "Hostel, this is good choice for people who is alone, who haven't a lot of money and who like a relationship with another people," he said.

But would he choose to live in one if money wasn't an issue? "No, obviously not, no," he said. "Every time, the main reason was money, every time I chosen the cheapest one." There are, he said, a number of downsides. "Very far to toilet. You haven't table, desk or furniture. More people, less space. Not private space."

The author next to his bunk

Had he saved any money while he'd been staying here? "Honestly, not really. Not really. I try now earn some money, to go to Poland. This is better for my family."

Some have been living in No.8 for even longer. I heard estimates as high as five years, but none of the longest-term residents I spoke to were willing to be interviewed for this piece. It seemed that having to live in a hostel was an uncomfortable fact, best not dwelled on.

A lack of private space clearly affected people. You could spot a No.8 veteran by how they obtained privacy. One had wrapped sheets around his bunk to create a gloomy den. Another wore expensive, custom-fit earplugs whenever he was in a public area. I saw a third eating her meal in the kitchen. She had tucked her plate into the furthest corner and twisted her body round, facing away from everyone else as much as physically possible.

Rachel

Rachel, the hostel manager, estimates that 10 percent of the residents of No.8 are long-term; by my count, the number is even higher. Why did she think people ended up living here? "You never know someone's history. I work in the hospitality industry, I'm not going to ask people about their personal issues," she said. "But I think some of the people, maybe they have problems, or they did, and they just find it easier staying here. At Christmas time, I'll get them a card, buy them a a present, because they're not home with their own family. I don't know what's happened, so it's nice to make them feel a bit welcomed, like they're not alone."

A week of disturbed sleep had left me struggling. After waking 15 times every night, the heavy, drooping bags under my eyes made it look like I'd been punched out by Manny Pacquiao at least four times on each side of my face. Too exhausted to teach, my lesson plans started to include sections called "Play Match Attax" and "Get Oliver to describe the plot of Minions again."

But losing sleep is only half of the problem. The worst part of hostel living is the impossibility of spending any time alone. When you take a dump there are people queuing outside. The lights in the shower switch off automatically after ten minutes. Everywhere else, there's always somebody there – and people become strange when their private behaviours are a public spectacle.

Guests playing darts in the hostel pub

It was karaoke night as I entered the pub on the ground floor of the hostel. Two maroon-haired ladies were performing "Don't Stop Believin'" in two completely different keys. As I shuffled towards my room in the back, the ponytailed DJ boomed into the mic: "Loverly stuff, ladies. Lov-er-ley stuff."

In my hostel bed one final time, I carried out my nightly ritual – adjusting the pillow so it covered the mysterious bloodstain on my sheet. Tucked in nearby, a Russian man carried out a muttered phone conversation, even though it was well after midnight. As he hung up, he rolled onto his side.

"Sorry," he shouted in a unsteady voice. "Sorry for disturbing you, everyone. Sorry for making this noise. But I miss my wife. I have to speak with my wife."