'The Girl With the Dragon Tattoo' actress was shy and introverted while at school and found it a particularly difficult time socially and, although she has got better, she still spends a lot of alone time.
She told LOOK magazine: "I was very, very, shy. I had problems with anxiety and not being able to relate to other people. I would spend all my free time in school by myself. I couldn't relate to other people or get myself to feel comfortable hanging around with other kids in school and it wasn't the happiest time of my life.
"It took me a long time before I felt more at ease making friends and not putting up walls around me. I still like the time I spend alone, just thinking by myself or watching people. I need that kind of quiet time."
The 28-year-old star had her nipple pierced and wore leather and fake tattoos for her role as Lisbeth Salander 'The Girl With the Dragon Tattoo' and admits her personality lends itself to darker roles.
She said: "I tend to be guarded and that suits me being in darker kinds of films. I can easily slip into characters who don't laugh and smile a lot."