In 1977, in a bar in Vancouver, two brothers, Stephen and Tom Osborne, were drinking with a group of friends. The conversation turned to authors such as Voltaire and Kerouac, who were said to have written iconic novels in mere days. The whisky flowed. At closing time, filled with Dutch courage, each promised to return three days later having written a novel of his own.

Thus began the “3 Day Novel Contest”, the deformed left foot of the literary world. Over the years it has attracted a range of madcap entrants, including a man who wrote his novel up a tree, people who wrote their novels live on reality TV and a woman who twice — twice — entered in her final month of pregnancy. This year I decided to enter. Like most novelists, my output is ordinarily 1,000-3,000 words a day. Under the rules I had to write 45,000 words in three days. What could possibly go wrong?

Day 1 4am I awake to pitch blackness. I am in the Arvon Creative Writing Centre in middle-of-nowhere Devon, the perfect location: no internet, no mobile phone signal, no distractions. No other people, in fact. For breakfast I force down a bowl of slow energy-releasing muesli, on the advice of Mark Ellison, the nutritionist for Manchester United, who has given me a “nutritional strategy”.

5am I start my first five-hour session. It is a punishing schedule. First session 5am-10am; second session 12pm- 5pm; third session 7pm-midnight. Then up at four the next morning, ready to begin again. It is so dark outside that it could be the middle of the night. I have come prepared. A few days ago I met Donna Cumia from sadbox.com, who treats depressed horses with artificial sunlight therapy. She lent me a daylight-simulating lightbox, saying that it enhances your serotonin levels, energy and concentration. I switch it on and my room is transformed by a glow to equal a summer morning. This would prove to be the most useful piece of kit I could have asked for.

I start writing and am surprised how easily the words begin to flow. There’s no time to agonise over the first line, so I just let it out: “When I arrived last night, after a small kerfuffle with the rooms — about which more later — I dumped my bags on the uneven mattress of the single bed I had been allocated, and without unpacking, stepped out into the brisk country air.” It doesn’t zing off the page, but it sets the tone.

I have come armed with advice on mental strategy from Dan Salcedo, the head coach for the British Olympic triathlon team, who recommended I be more than ready — “pumped up and climbing the walls” — a day or two before. So I have prepared well (contrary to popular belief, Kerouac carried out painstaking preparations for the creative binge that became On the Road). I have planned my novel in nine chapters to correspond to my nine writing sessions, and written an outline for each chapter. To make it easier for myself I have matched my ideas to the method. My novel will be about a novelist writing a three-day novel about his hang-ups, on his therapist’s orders. Complicated and self-reflexive maybe, but it allows me to take my own experiences as a point of departure.

The day has been gruelling and my fingers ache, but at the end of it I am buzzing. With only three hours’ sleep ahead of me I know that tomorrow won’t be easy.

Day 2 Getting up is painful. Jeffrey Archer, a famously disciplined writer, wrote a million words in prison. Before kicking off I asked him for advice. “Oh, poor Jake,” he said sarcastically. “Get off your backside, man, and get on with it!” With these words ringing in my ears, I haul myself out of bed.

A key part of Day 2 is power naps. I survive on ready meals and begin to inhabit the life of the novel more vividly than the real world; this is Cartesianism in action.

Alexander McCall Smith, the author of “those books about Botswana”, who produces four novels a year, advised me to become “an amanuensis for the unconscious”, like a “tennis player who flows into the strokes without thinking about it”. So, whenever I encounter an obstacle, such as how to spell “transmogrified”, for example, I simply highlight it and move on.

My “flow” leads me into the long grass when I find myself writing a sex scene — difficult at the best of times. I fall into the usual traps: “the world turned on its axis, and the stars winked out, and their bodies united in passion”. I read it back and am horrified. Fixing it sets me back by half an hour.

Just before the last session I make the mistake of having a hot bath and at about 9pm find myself nodding off. I make a strong Irish coffee and, on the stroke of midnight, I hit my target: 30,000 words.

Day 3 The final day is the most gruelling. On the final stretch I fall victim to hubris and relax my pace. I launch a desperate final “putsch”. Eventually I type “End” at 2.20am, two hours and forty minutes before the deadline. The final words are: “It is possible — perhaps — that this is a competition I can win.” Out of context this sounds triumphalist. But who cares? 45,000 words in 72 hours — I’ve done it.

I have the shakes, my eyes feel like meatballs and I look vampiric. I am on a high; I can’t bear to leave my characters, who, for three days have been my only company. But, my God, it feels good.

Jake Wallis Simons is the author of The English German Girl and The Exiled Times of a Tibetan Jew. His 3 Day Novel is no longer generally available online. If you would like to read it in ebook form, send an email to info@jakewallissimons.com. Competition details at 3daynovel.com