The supernatural erotica, which has abundant steamy and bold scenes, features Sapna in a lead role as a conniving seductress Meera, and Ali Fazal as Kabir, a writer in search of a story. Gurmeet Choudhary plays Meera's husband Jaidev in the film.
"Intimate scenes were not difficult. The difficult scenes for me in the film were the heavy emotional ones," Sapna told IANS in an interview.
"There were times when I cried all day on set. I couldn't stop crying, it was a very emotionally heavy scene I had done with Gurmeet one day. It was really difficult for me to snap out of Meera's character," she added.
Sapna, who is known for her role as Kiran Rathod in espionage drama TV series "24", finds her journey from TV to Bollywood "unreal".
"It was because of '24' that I got 'Khamoshiyan' and a lot of other things also. It was four months after '24' that I signed my first film. It's been unreal. I've got great friends in Mumbai. I couldn't have asked for a better journey," said the 24-year-old Bollywood debutante.
Speaking about her attachment with the film, which released Friday, she said: "'Khamoshiyan' is close to my heart. I'm very overwhelmed and the film has been a great gift to me."
Her dark and mysterious character in the film has a lot of secrets and is "very complex".
"Meera is a very complex character. She has a lot of different layers and shades to her personality. She carries a lot of dark secrets from her past. She likes to play mind games and she is very dark and mysterious," she said.
Asked if she would still want to work for TV, having already made a Bollywood breakthrough, she said she wouldn't mind and would be happy to "break the barrier" between Bollywood and TV.
"In Hollywood, everybody acts in films and then they act for TV, so I feel somebody has to break that barrier in Bollywood.
"Acting is acting, no matter where you do it, whatever the medium may be. I hope Bollywood and the Indian TV industry break that ice. It'd be nice to see more filmy faces on TV," she said.
Sapna also expressed her fascination of veteran actress Rekha and her talent.
"The roles with more depth attract me. I'm in love with roles that Rekha ma'am has pulled off in the past. 'Khoon Bhari Maang' is my favourite film and Rekha ma'am is my favourite actress.
"The great thing about her is that she used to stand out in the scenes all the time and she still does. I'd love to do roles that have more personality to them rather than the look on screen," she said.
Although she is a "huge fan" of superstar Shah Rukh Khan, Sapna also appreciates Manoj Bajpayee's work.
"I'm a huge Shah Rukh Khan fan. I've watched his films more than anybody else's. And, I'm a huge fan of Manoj Bajpayee too," she said.
