The film, which is expected to go on the floors in September this year, will be directed by Vipul Shah, who has made films like `Namastey London`, `Waqt: The Race Against Time` and `Aankhen`.
`Before I Go To Sleep`, which released in September 2014, was based on a book with the same name by author S.J. Watson.
Vipul Shah has bought the rights to adapt the film.
`I was keen on working with Saif Ali Khan and had signed him already and was looking for a script. Vipul came to me with this story and I thought Saif fit the role and it was great that he agreed to be a part of it. He is an actor who moulds himself with every character he plays with ease,` Kumar said in a statement.
Vipul said: `Saif is a great actor. He is versatile and while he has this lover boy quality, he can easily and comfortably also move into an intense part of the film.`