Although Emily Browning didn't have a problem with nudity in this movie, she says the scene with the man who licks her face wasn't the most pleasant thing to film: "It was weird for the first few takes, to be honest, especially the cigarette burn on the neck. I actually had prosthetic skin put onto my neck so he could actually burn me and I wouldn't feel it. But still, for the first two takes, I flinched, especially when someone puts a cigarette to your neck. Julia spoke to me about learning to meditate through those scenes, so I was focusing on my breathing and learning to shut myself off. I also think I get this kind of weird, super human strength when I'm in front of the camera because it's what I love to do."
Director and writer Julia Leigh originally based the idea she had for the film on a recurring nightmare she had that someone was watching her while she slept.
Before filming, Emily Browning was urged by director Julia Leigh to watch Lars von Trier's Antichrist (2009) and study Charlotte Gainsbourg's performance.
The 66-page first draft of the screenplay made the 2008 Black List, a list of the top unproduced screenplays in Hollywood voted on by industry professionals.