Where do you begin writing a novel about two vigorous young people who become incapacitated through illness? I decided to start mine on a gruelling climb halfway up the Alps as evidence that they had once been fit and normal. But I soon realised that if the chief protagonists were able to do little more than lie on their beds, the narrative would lack drive. I had to climb inside their heads to find where the new action was.

The mission, to create a fast-moving plot with compelling characters around the unlikely subject of chronic fatigue syndrome (CFS), started over lunch with my editor. I’d brought along several outlines for my next book. I mentioned CFS only in passing as the reason why my productivity had declined so dramatically over the past few years. Yet this was the topic that created most interest. “A couple of eccentric kids who don’t get up for a decade? Sounds like Oblomov (a 19th-century Russian novel about a man who refuses to get out of bed). Tell us more about the background.”

“Well,” I said cautiously. “Two of my own sons have had CFS. It lasted 10 years.” Their lives had shuddered to a halt just as they reached adulthood.

One was hoping to become a musician; the other was a research geologist. I explained about their years of increasing disability, of the effects this had had on their siblings and our home life.

We already knew about disability. My middle son has learning difficulties.

His childhood had put incredible demands on the family. Yet his sister and two brothers were always supportive: helping him, encouraging him, incorporating him into their activities. When his two brothers became ill, this slow learner was at first baffled, even irked, by their vulnerability.

Surely it was he who was supposed to be looked after by them? Gradually, he came to understand the altered situation: that he was now the strong one, the carer.

CFS is unpredictable. There were several years of relapse and respite. I explained to my editor about the extraordinarily rich inner lives of the sufferers, involving silent jazz bands, mental gymnastics, invisible mountains, political imprisonments; worlds they created for themselves after they had lost almost everything else, including, for a while, the ability to see and hear properly. “We definitely need a story on this,” she said.

Among the estimated 240,000 sufferers in the UK are several thousand schoolchildren, some as young as seven. Sir Liam Donaldson, the Government’s chief medical officer, has declared it a major health problem, yet it remains little understood. There are handbooks and websites on how to survive, and several anthologies of poems by child patients. But, as far as I knew, no novel.

The editor commissioned the book. I signed the contract, then was disheartened. Did I want to return to my own bleakest decade and to those bewildering years of upheaval at the onset of my sons’ illness? Yes, I did, especially if it meant putting on record their courage and the support of their siblings. Their sister repeatedly travelled back from her work in Glasgow to give practical and moral uplift to us all. At weekends, their brother helped me in the kitchen, emptied the bins, filled log baskets, hauled them indoors. He learned to wield the axe and chop the firewood.

In writing about a disrupted family life, I aimed, not for the gut-wrenching memoir of prolonged torment, but rather for an action story to confirm how apparently eventless lives can have their own significance, variety and validity. A fellow writer said: “You ought to put a furry animal in there somewhere. Sad stories about terminal illnesses need a pet for the reader to relate to.”

“CFS isn’t terminal,” I said sharply. “By the end, everybody’s situation has changed and the characters are definitely better.” Or, I might have added: “As better as it is realistic to allow them to become.” This fiction wouldn’t be offering any exaggerated expectations of total recovery.

However, I responded to the advice. Although I hadn’t, till then, involved my family with this fiction, beyond admitting that I’d initiated it, I queried my sons about whether animals had any relevance. “Of course! Don’t you remember, Mum, about the cat? Often she was the only loyal friend we had left in the whole world.” So the ancient family mog was transmogrified by fiction into a black Labrador with a far greater role than I’d realised.

Young people debilitated through chronic illness can find the non-verbal, non-judgmental attitude of animal friends immensely reassuring.

The CFS world is a minefield of self-proclaimed experts, contrary specialists, peddlers of false cures. I had no wish to join them. However, I did need to ensure that there was no misinformation in my tale. The first reader of the typescript was a medical researcher who returned it with the surprised comment: “It’s quite a page-turner. You wouldn’t have thought two boys being ill would make much of a story, would you?”

Then it was my editor’s turn. She said: “Are you sure you want us to publish this? You could submit it to an adult list.”

No way. All along, I had wanted young adults to be my preferred readers.

The original title was “The Ice Men”, an intimation of the low body temperature of many CFS patients, and a reference to the 5,000-year-old frozen man who was discovered in the Austro-Italian Alps in 1991. Inert though he is, he takes on a significant role. Unfortunately, this title conflicted with another Oxford University Press book, Geraldine McCaughrean’s The White Darkness, about Antarctica. After reading the draft, my editor said: “This isn’t just about CFS. It’s about everything!”

So the next title idea was: “The book about everything including green mint tea, chess with no board, maggots munching, the silent piano, blindfold prisoners in the dark, the eight-piece Brazilian festival band, a blade of grass, angels with dreads, the mysteries of tulips, a rhinoceros, New Zealand, rotten apples.” Eventually, we came up with This Strange New Life, with the list of topics flowing down the title-page inside a skeletal head.

All three sons, now in their thirties, are getting on with their own lives. Middle son is firmly settled in his group household nearby. Eldest son has become a poet and collaborates with his wife on creating art installations. Third son is doing a music degree. His department has arranged a special, slowed-down version of the course, spread over several years, so that he can pace the work according to his fluctuating abilities.

I decided not to dedicate This Strange New Life to any of my sons, but to our cousin Rachel who was hit by CFS in her teens, seven years ago. I doubt she’ll be able to read the book for some while yet. She lives in a hushed, semi-darkened hospital room with 24-hour care. However, I know - and I want her to know that I know - that however helpless she may appear to be, there is great activity and creativity going on inside her head. One day, when she is strong enough to hold her own pencil, she will surely write her own tales of her strange new life.

This Strange New Life by Rachel Anderson is published by Oxford University Press, pound;5.99