At the time, my daughter was three years old and I invented nothing (apart from the ending). I simply compiled the best bedtime moments. Since I called her "little monster" all the time, I truly drew a little monster, taking care not to show whether it was a boy or a girl.

At the end of the book, little monster kicks back: the daddy of a little monster needs must be a monster.

The only moment when little monster is calm is when it listens to its favourite book: "Where the wild things are" by Maurice Sendak, a great classic.

When the book came out, I was rather sceptical. I wondered whether it was too personal. But the book has become a great success. Parents come to tell me that they recognise the situation which they experience every evening with their child. It’s always around the age of three that the child does everything in its power to put off bedtime. It’s a help for everyone to know that we share more than we think. Besides, with a touch of humour, everything is lighter.

Game: when I received the printed book, I realised that there was a mistake in the drawing of the toilets. I was devastated, but surprisingly nobody has ever noticed. You’ve all been to the loo, so look properly… spot the mistake (and it’s not in the pipes!).