Make yourself comfy...

As an eight-hour enactment of The Great Gatsby opens in the West End, Larry Ryan shares his survival tips for a stint in the stalls

Write stuff: scenes from 'Gatz' (Mark Barton)

It's light and day when you enter the theatre; it will be night and dark when you leave. This is the proposition facing the viewer on attending Gatz, the acclaimed staging of The Great Gatsby which opens tomorrow at the Noël Coward Theatre, as part of the London International Festival of Theatre.

The play, billed as "The Great Gatsby Uncut", from the New York experimental theatre company Elevator Repair Service, clocks in somewhere between seven-and-a-half to eight hours. The performance itself is about six hours long, but comes with two 15 minute intermissions plus an hour and half break for dinner. It's theatre as Test cricket only less boozy and without the option of declaring or the prospect of a rain delay.

For the show's 13 performers it's rather more like theatre as marathon running. "They serve us energy bars in chapter four, get a cigarette in chapter eight, and maybe if you're lucky a shot of whiskey," Jim Fletcher, the actor who plays Jay Gatsby , told the Huffington Post during its recent New York run. "It structures your day."

I saw the show in 2008 at the Dublin Theatre Festival. Your day begins in the early afternoon; performances for the London run kick-off at half two. There was tension as I settled into my seat – I was facing down an eight-hour play. Eight hours! What was I doing? Why does any play need to be eight hours long?

Here's why. An actor enters the stage, which resembles a drab office some time in the last 25 years. It's apt – as well as being theatre as cricket and a marathon, it is theatre as a day at the office. The actor sits at his desk, sets down his cup of coffee and fiddles with his computer. It won't start. While waiting for someone to fix it, he happens across a copy of The Great Gatsby on his cluttered desk.

He begins reading aloud in a flat tone: "In my younger and more vulnerable years..." Spurred on by curiosity or remembrance of what lies ahead, he continues to read, with greater animation. The actor is Scott Shepherd, and he can recite F Scott Fitzgerald's seminal jazz-age novel from memory. As the performance unfolds Shepherd embodies Fitzgerald's non-judgemental narrator, Nick Carraway.

Every word of the book is spoken aloud – each "he said" and "she replied". As Shepherd recites – he appears to be reading but it's all from memory – other actors enter. They start out as co-workers in the office, bemused by Shepherd's reading, but eventually they too become versions of characters in the book, Jay Gatsby, Daisy Buchanan, Jordan Baker, Tom Buchanan, Myrtle Wilson et al, interrupting Shepherd with their own lines. It's part ensemble piece, part movement theatre.

ERS are serious about the endeavour, but not po-faced. Gatz is lots of fun. The performers and its director John Collins skillfully draw out the humour of the book with great timing and drunken party scenes played out as slapstick farce. The time sails by.

I first learned of Gatz while living in America in 2006. ERS planned to stage the production in New York in 2005 but a rights issue got in the way. They took matters into their own hands by staging an invitation-only show. Eventually the Fitzgerald estate got wind of the underground production and put a halt to it. That, seemingly, was the end of Gatz.

Of course, there was a second act. ERS was allowed to stage Gatz anywhere outside of New York and Britain. The first performance was in Brussels, with more taking place around Europe and Australia. In 2010 ERS brought the show to New York. Rapturous reviews followed with The New York Times naming it the play of the year.

When I saw it at the Project Arts Centre in Dublin, they offered free espressos during the intervals. I would caution against too many. Bring water. And wear casual clothing. I went solo, as I couldn't face dragging anyone along with me. Judging by the looks on the faces of friends when I told them about what I was intending to see, this was the right decision.

Many will balk at the play because of its length – it's not one for someone who hasn't read the book – but, as The New York Times critic Ben Brantley put it, "to turn down the offer would be to miss one of the most exciting and improbable accomplishments in theatre in recent years".

Feats of endurance theatre aren't all that rare. Every so often someone will get the gumption to make something monumental. One of the hits of last year's Edinburgh Fringe was Hotel Medea, a multi-disciplinary, immersive event that ran from midnight to dawn. It transfers to the Hayward Gallery in London next month. In May, Einstein on the Beach, Philip Glass and Robert Wilson's 1976 avant-garde opera which runs at just under five hours, made its debut in the UK.

The assumption with such long affairs is that you'll be bored, that you'll fall asleep. I didn't find the length a problem. When you've set aside a day to see a show, you're coming into it fresh, rather than landing at the theatre, tired, at the end of the day.

Gatz is one of a number of Gatsby adaptations due. As of 1 January, the book is in the public domain – a little over 70 years after the death of the author – so it has become rather easier to perform. A musical version is planned for London's Kings Head Theatre. Another has already been staged at Wilton's Music Hall, with a speakeasy setting. And, of course, there's Baz Luhrmann's big budget film due later this year. The trailer for the film, starring Leonardo DiCaprio, Tobey Maguire and Carey Mulligan, would suggest that the immersion in Fitzgerald's world will come through swooping cameras, beautiful costumes and wild party scenes. And, for some reason, via 3D glasses too.

The novelist Jonathan Franzen said of Fitzgerald: "Here is somebody who found a way in 50,000 words, to tell the central fable of America. And that is such a ponderous, heavy, enormous undertaking, and yet, you feel like you are eating whipped cream."

Gatz in its all-encompassing way manages both the heaviness and the lightness. The play is about the act of reading, dramatising how a reader falls in love with a book. As Shepherd concludes, saying those gorgeous last sentences, "And as I sat there brooding on the old, unknown world...", you want him to turn back. I wasn't worn out after all that time. I was giddy with Gatz. After it all, you're tempted to read the book again. Even now, I'm tempted to see it again. It's only eight hours.

'Gatz', Noël Coward Theatre, London WC2 (020 7452 3000; nationaltheatre.org.uk) to 15 July