As the creator of Scandi-noir thriller The Killing, S0ren Sveistrup has enjoyed the sort of success most screenwriters can only dream of. First shown on BBC4 in 2011, The Killing quickly became a cult success, despite being foreign and subtitled. It won a Bafta, ran for three seasons, and was the forerunner to other hit Scandi dramas, such as The Bridge.

Yet the accolades, attention and offers of work heaped upon Sveistrup, who was billed the biggest Danish export since Carlsberg, have at times proved hard to handle, he admits.

Screenwriting by day, working on his debut novel at night, with a young family too, something had to give.

"After The Killing, I got more invitations to do certain work. Suddenly you look at your schedule and find that you're owing people three TV series, two movies and a book," he recalls.

It culminated in a breakdown two years ago, when he collapsed at home in Copenhagen.

"I had become very stressed. I had booked myself too much. I had a problem with saying no," he explains.

"It's not called a nervous breakdown here, it's a 'stress-related' collapse. I was at home and then one morning I didn't want to go to work, I felt nauseous and I just emailed my friends saying I was totally stressed, was raising the white flag and cancelling everything. I did the same at work. I didn't do anything for months."

He saw a therapist, which he says helped enormously.

"When you're very stressed, it's because you can't say no. You say yes to your work, yes to your wife and yes to your kids - and finally there's no room for you. If you don't leave space for you, you suffocate.

"It is healing to talk about things that are traumatic for you, and the same goes for stress. The wonderful thing about therapy is that it really works."

The episode forced Sveistrup to rethink his life, and gave him time to complete his debut novel, The Chestnut Man - a nail-biting, atmospheric thriller in which a killer's calling card is a chestnut man doll left at the scenes of his crimes.

The book introduces us to two new characters, Naia Thulin, an ambitious young detective, and her partner Mark Ness, a burned-out investigator who's just been kicked out of Europol. Their unlikely chemistry is as much a draw of the novel as the gritty plot itself.

"Thulin and Hess are two sides of me - Hess is the guy being burned out. I felt burned out at the time and I gave something of that to Hess. Thulin is another side of me - the one who was fed up with feeling burned out and just thinks he's lazy and egotistic. I just had conversations with myself."

The book has been sold in 25 territories, is already a bestseller in Denmark, Holland and Norway, and is attracting interest in screen adaptation.

"It seems like it's going to be adapted - but I'm not allowed to reveal details. My company is negotiating those things," Sveistrup explains.

"When I did The Killing, I had a free hand, and I think it's important that the creative team who do The Chestnut Man also have free hands to try to develop something they think would be interesting."

The 51-year-old - who lives in Copenhagen with his journalist wife Kristina and two sons, Silas, 12, and nine-year-old Sylvester - doesn't want to write the screenplay, preferring to focus on the second novel in the series.

That doesn't mean he's completely closed the door on thinking about TV, though.

In The Killing, Sofie Grab0l played the strong, cool, resourceful and emotionally detached detective Sarah Lund, who became almost as famous for her trademark jumpers as for her crime-solving skills. At a time when TV was very much seen as inferior to movies, The Killing was cinematic, dark, atmospheric and artistic - and the series helped to change television's kudos as an art form, Sveistrup believes.

Would he ever bring The Killing back?

"I wouldn't say I'd never bring The Killing back. Maybe one day I'll wake up and say, 'I have to do it', but has to do with a good idea and the financing and the actress. Who knows? We all know each other still, so there's no reason not to."

His own early life has influenced his work, too. The adopted son of two teachers, Sveistrup was brought up on Funen, an island off Copenhagen, and he recalls being a sensitive child.

"I remember lying in bed and being afraid of the monster beneath it. I think it's good to have a sensibility, but sometimes it makes you vulnerable, with a tendency towards anxieties. In my 20s and early 30s, I was like that. It came as a big surprise that I could earn a living by writing stories about it."

He says his parents had a miserable marriage and that he argued with his father. And when Sveistrup was 21, his mother, who had a history of mental illness, committed suicide.

"It's not something I talk about that much," he says, guardedly. "It changes your life totally and makes you very vulnerable. In a strange way, it makes you stronger. You find resources in yourself which you didn't think you had.

"In Nordic countries, we are afraid of telling others about our worries and traumas, but when we do we feel relieved. Back then, I said, 'This is not going to ruin my life. I'll take a shot at being happy anyway'.

"It's important to state that there's hope for people experiencing those kinds of tragedies. I have a good distance from it now," he adds. "Of course, I sometimes feel sad about things that happened in my family, but as you get older, you realise you are not on your own, as friends, family and even strangers can relate to it."

Sveistrup studied history and literature at Copenhagen University and gained a degree in screenwriting at the National Film School of Denmark, before becoming a screenwriter.

The creative process was - and still is - a great release for him, he reflects. But he realises how important it is to take time out.

"Instead of being absorbed in work, it's important to take time to be grateful for being here and enjoying the good moments. You have to be able to enjoy the good moments to cope with the bad ones."

The Chestnut Man by Soren Sveistrup is published by Michael Joseph, priced £12.99. Available now.