'Before I Go To Sleep' explores the darkness of losing one's memory to an accident, a fear that resides deeply in everyone and which Nicole Kidman displayed with remarkable commitment on the chilling movie adaptation with Colin Firth.

Nicole Kidman and Colin Firth in 'Before I Go To Sleep'
Nicole Kidman impressed Colin Firth with amnesiac performance

In a bid to fully immerse herself in the character of Christine, a 40-year-old woman who wakes up one day believing she is still in her twenties and with no recollection of who her husband is only to find out repeatedly that he has been introducing himself to her every day for several weeks, Nicole Kidman took the time to do some full research into her condition. 'I watched a number of documentaries where people do have this psychogenic amnesia', she explains. 'The idea of actually having this is horrifying.  Someone described it as like losing their soul, because you lose your identity, you lose actually what you are and that's really chilling, and it's also sad.'

More: Read our review of 'Before I Go To Sleep'

As it turns out, her studying paid off - at least in the eyes of her co-stars and those who adapted the story from the novel by S.J. Watson. Producer Liza Marshall gushed that she was the 'perfect' actress to take on the role, while director Rowan Joffe was amazed by her non-verbal performance and use of facial expression. Colin Firth admitted her attention to the role forced him to put his all into his own character, describing her work as 'chasteningly authentic'.

Watch the trailer for 'Before I Go To Sleep' here:

'Most of my research was to do with the condition, so that it was plausible, so that I myself could feel it and believe it, which is how I have to do every character', Nicole reveals. 'If I can't feel it and believe it, I'm hopeless.'

'Before I Go To Sleep' is set to hit US theaters on October 31st 2014.