Before I Go to Sleep is based on the novel of the same name by S.J. Watson, which I have previously devoured and loved. You can read my review of the book here. It’s one of those films whose effect is diminished a bit by knowing what happens. It is still pretty tense to watch, quiet and slow but building into something sinister.

It’s the kind of story that I imagine is hard to translate to the screen. Instead of a diary, Christine records her daily message to herself on a camera (and gives an excellent opportunity for product placement). I can understand why that could work better on the screen but doesn’t strike me as easy to do in secret; her situation is all about keeping it secret. And she must have had to spend ages watching it back every day. A written record just makes more sense. The ominous music throughout was a bit much and set it out from the start that there was something dodgy going on. I guess it has been marketed as a thriller but it makes her confused fear into something more much earlier on.

Not read the book? You might want to stop reading now as there are some things I want to talk about which are a bit spoilerific.

I thought the casting was a stroke of genius. Colin Firth is so often the good guy, or the misunderstood Darcy figure of course, and Mark Strong is placed firmly in my head by that Jaguar advert as one of the bad guys. I did feel in the film that Ben was painted as too obviously shifty from the start. I know in the book she writes in her diary that she can’t trust Ben, but the way it’s written gives him the benefit of the doubt. He is caring and patient so why would we instinctively distrust him? He just didn’t come across so much as the devoted, loving husband on the screen. More just resigned to his fate.

Mark Strong’s voice is lovely and soothing, something you’d definitely want to hear on the phone every morning. I didn’t really feel the same sort of attachment between him and Christine as in the book. There’s just a little scene where she tries to kiss him but it seems out of context.

Overall I enjoyed the film though. It got a bit overly sentimental at the end, a scene my boyfriend said he would have preferred to go without. The reunion in the book was clearly too brief for film-makers who like to squeeze a bit of extra emotion out of their audiences.

I would love to hear your thoughts if you saw the film withour reading the book first.