For someone whose first book was lauded as "a real one-off" by author and memoirist Blake Morrison, Sathnam Sanghera is remarkably understated about his recent successes. "It's constantly bemusing and surprising," he says of the public and critical reaction to his memoir, The Boy with the Topknot. "It's a bit presumptuous to think at the age of 28 that anyone would give a shit about your life. Why would anyone care?"

As it happens, people do care about what Sanghera has to say. He has picked up a panoply of awards, including Mind Book of the Year 2009, and, judging from the hundreds of emails he has received "from a whole range of people", interest in what he has to say is pretty broad.

In part, the book - subtitled A Memoir of Love, Secrets and Lies in Wolverhampton - is a hilarious gallop through the typical teenage frustrations of growing up in a provincial town, with frequent musings about escaping for something more exciting. "I used to say it gives meaning to your life growing up in a crap town because it makes you want to get out," Sanghera says. But what really resonates is his observations of life in a Punjabi Sikh family in the 1980s and 1990s, and the book's central thread - an incredible depiction of how he and his family came to terms with his father and sister having a serious mental illness.

Personal crisis

Asked why he did not fictionalise his story instead of exposing such personal details about his family, Sanghera says simply that he "absolutely had to write" a memoir. It was a visceral response to what he could "only describe as a real personal crisis", triggered by the discovery in his late 20s that he had spent his entire childhood in a house with two people who had schizophrenia that he was never told about. It led him on a sometimes tortuous familial odyssey that altered his whole outlook on life.

Sanghera gave up a highly paid job in London - he was, and still is, a successful newspaper journalist - to return to the town he grew up in, live with his family once again, and attempt to make some sense of the unwanted revelation. "It felt increasingly ludicrous spending time writing about strangers when there were more important subjects at home," he says, with typical bluntness, in one chapter.

The contrast between Sanghera's recollections about his life in London, interviewing celebrities and attending dinner parties with his media buddies, and the warm, painfully personal exposition of family life is telling. An expression of pure mortification drifts across his face when he recalls his time as a media hack in his 20s. "I was a bit of a twat," he admits. "My life was nauseating. I was in such denial about my Wolverhampton past. I didn't think about it and I loved the fact that [life in London] was so different. I was really seduced by all that, in an easily impressed immigrant way. Now I'm not so easily impressed."

Sanghera set himself the task of learning about his sister's and father's illnesses in detail. For two years, he immersed himself in family life, interviewing his parents, siblings and other relatives - but in particular his mother, who, among other things, endured domestic violence in the early years of her husband's diagnosis. "I found listening to my mum's story agonising, so painful," he says. "I literally spent a month just staring at a wall when I found out what she had been through."

However difficult it was for his family to come to terms with two members being diagnosed with a serious mental illness, Sanghera says he is grateful that the wider family were on hand to offer support. "It's amazing. When they come together, they are formidable."

Sanghera also researched schizophrenia more generally, talking to doctors and experts in the field. As well as the personal journey, Sanghera's book is peppered with journalistic extracts examining the myths around mental illness, and media portrayals of people with schizophrenia. As with many families in which there has been a diagnosis of schizophrenia, Sanghera's attempts to grapple with the misconceptions around it are a tale of repeated frustration. Of one psychiatrist who claims that people with schizophrenia have "a fake disease", Sanghera concludes that he "evidently needs a kick in the bollocks". It is as if by writing that he finds his own catharsis. "Even if you persevere with the eye strain engendered by reading scientific papers, the only thing you'll discover is that there is as much agreement about the causes of schizophrenia as there is agreement about the meaning of Shakespeare's plays."

Sanghera says the research was a crash course in a subject he knew nothing about, and that the unexpected and welcome outcome was that, by going through it he has inadvertently helped others. "I think one of the very satisfying things about writing the book is that a lot of people have picked it up wanting to be entertained or amused - and they have got that from it - but at the same time they have accidentally learned something about mental illness," he says. "And these are people who wouldn't normally think about mental illness."

Assumed links

That the book ended up challenging conventional misunderstandings around mental illness - particularly the assumed links between violence and schizophrenia - was not something he had planned. Rather, he says, it evolved as he delved into his family's history. "The link between violence and mental health as depicted in the media? It's a very simple point, but it's absolutely taboo in the media to say, when someone has committed a crime because of a mental illness, that they did it because of the illness. They're not evil, but you cannot say that. You'll be some liberal do-gooder." He adds: "It's a really important point to make. This is something my mum feels really strongly about. Whenever she talks about my father, she always says: 'He's ill.'"

Sanghera says his only regret about writing the book - he is adamant that his family have never objected to it or said they were unhappy about their personal lives being stripped bare - is that he included so many "embarrassing" vignettes about himself. "I spent so much time worrying about what I was writing about my family that I didn't think about what I wrote about myself. I wish I hadn't portrayed myself as such a twat. I would like to emphasise that I am not quite such a twat now."

Sanghera says he doesn't mind that the book has had its vocal critics, although few in number. One blogger has even accused him of "betraying" the Sikh religion. "I suppose the thing is with mental illness that once you've been through this, nothing really affects you," he says. "If your family love you, everything else is background noise."

In October, Sanghera will be a writer-in-residence at the Cheltenham Literary Festival, and he has plans to write novels. He may even write about mental health again in the future, but for the moment at least he says he wants to draw a line under it. He says: "A large part of me just wants to move on, but a large part of me really cares and wants people to know about it and to understand."

• The Boy with the Topknot: A Memoir of Love, Secrets and Lies in Wolverhampton, by Sathnam Sanghera, is published by Penguin. Order a copy of The Boy with the Topknot for £9.99 with free UK p&p

Curriculum Vitae

Age 32.

Status Single.

Lives North London.

Education Wolverhampton Grammar School; Christ's College, Cambridge, BA, English language and literature.

Career 2007-present: columnist, the Times and monthly car reviews for Management Today magazine; 1998-2006: Financial Times, chief feature writer, and news reporter in the UK and the US, specialising in writing about the media industry.

Interests Motoring, music.