John O'Connell writing in The Guardian is full of praise: "it's exceptionally accomplished – like David Nicholls's One Day, a brilliant example of how an unpromisingly high-concept idea can be transformed by skilful execution", "The structure is so dazzling it almost distracts you from the quality of the writing. No question, this is a very literary thriller." and concludes "The most unnerving aspect of Before I Go to Sleep is the way it is rooted in the domestic, the suburban, the trivial. Forget whizz-bang futurism: it proceeds from ordinary life in tiny, terrifying steps, and is all the better for it. The Escher staircase has an oatmeal carpet."[7]
James Kidd of The Independent has reservations :"Watson's take on the material is clever, convincing and moreish. Christine's life is mundane, but filled with tantalising possibilities: the early chapters fly by as you wonder exactly who to trust. The fun comes from spotting the plot holes that Watson later exploits for all they're worth." and he concludes "The ending feels hurried; a sentimental postscript to the meticulously plotted main event. But these are minor gripes. Before I Go to Sleep is an enjoyable and impressive first novel."[8]
Craig Ranapia in the New Zealand Listener is also unconvinced: "Watson scrupulously plays fair as he unpicks the tangled web surrounding our heroine, until the denouement. The last section turns on a character’s opportune inattention – after being surreally observant for the previous 300 pages – so the last piece of the puzzle can be uncovered. It was a cheat I couldn’t forgive or forget." but concludes "Before I Go to Sleep is still a slickly readable trip across familiar ground that leaves me looking forward to Watson’s second novel."[9]