Have you ever been so deep in to a box-set binge that Netflix has checked in to politely ask if you’re still watching? The 50-Hour Improvathon, which comes to Wilton’s Music Hall next weekend, is kind of like the live version.

Now in to its 12th year, the event is a marathon of live performance, where a cast of improvised comedians tell a story split across 25 soap opera episodes. It starts at 7pm on Friday February 15 and concludes, 50 hours later, at 9pm on Sunday. This year’s show is called The Good, the Bad and the Fifty and is set in the Wild West.

“It’s like nothing you’ve ever experienced before,” explains Pippa Evans, who co-directs the show alongside Adam Meggido.

“The actors create this entire world, and at the end of the 50 hours you cannot believe it has finished. One year, I was playing Jet from Gladiator, and I was on the tube three days later looking around and wondering why nobody was asking for my autograph.

“I still thought I was Jet!” she laughs, “There’s just something about the depth in which you go in to your character.”

Of course, the sleep deprivation can’t have helped either. Performers including members of The Showstoppers, Dr. Who regular Dan Starkey, Ruth Bratt, Cariad Lloyd and stars of the hit West End show, The Play That Goes Wrong, will each go many hours without sleep, with some making guest appearances and others featuring in the complete set of 50 hours.

“I’ve done the full 50 hours a couple of times,” continues Pippa, “some might do four or six, but others will do the whole thing.”

“The idea is that after 30 hours of being awake, suddenly you are performing without any blocks or filters and it should be the most purist form of acting.

“By 30 hours, you have people break out in fits of giggles, someone might start to cry or another character might deliver an incredible monologue, which suddenly means the whole show makes sense.

“After one year, I thought I felt fine, but when I tried to leave the theatre I couldn’t find the door. It was like the door had been removed and I was just stood in a box, I was hallucinating from the sleep deprivation!”

Seeing out the full 50 hours isn’t exclusively up to the actors, either. “Some audience members come for the whole thing,” Pippa points out, “they follow the full storyline and they’re not allowed to fall asleep – if they do they have to leave the theatre.

“It becomes a bit of a competition of who can stay awake the longest, so some do take a break and go home for a nap.”

The Improvathon was originally created by the Canadian troupe Die Nasty, before it was brought to London by Ken Campbell. Each year sees the show adopt a different theme – last year’s Strictly Not Dancing was staged at south London’s Stockwell Playhouse – and the production features both a live band and a bar serving hot and cold drinks all night.

The show can attract crowds of people not quite ready to go home after nearby pubs and clubs have shut, but there’s also a Family Episode suitable for children on Sunday February 17 from 11am.

So why has the Improvathon proven such a hit?

“For the audience, there are three things. It’s a theatrical experiment that doesn’t exist anywhere else and you get to watch a story unfold with some of the world’s best improv actors on a stage together. They take their whole weekend off to do it, and you get some really good, funny acting.

“Thirdly, the cruel side of the human brain is that they’re kinda hoping they are going to see someone break down a little bit. They want to say ‘I was there at 3 in the morning when Pippa Evans started to weep because the penguin died.’”

Lastly, I asked why those who might be sitting on the fence should come down and give the Improvathon a chance.

“Because the improv-philosophy is: always say yes. Also, why are you sitting on a fence? That sounds really uncomfortable.”

The Good, the Bad and the Fifty starts at Wilton’s Music Hall at 7pm on Friday February 15. Tickets can be bought for separate episodes or a full-weekend pass. More details are here.