In the horror movie Lights Out, American actress Maria Bello plays a mother who talks to a figure only she can see, a habit that terrifies people around her.
The 49-year-old, known for her roles in A History Of Violence (2005), Prisoners (2013) and the television drama ER (1997-1998), tells The Straits Times she drew on a mental disorder she has suffered to play Sophie, a character prone to violent mood swings.
Her 2015 book of autobiographical essays, Whatever... Love Is Love, revealed that she has coped with bipolar disorder for more than two decades.
"I had it quite young, but wasn't diagnosed till I was 28. Thank God I was or I probably wouldn't be here right now," she says in a recent telephone interview from the United States.
She has embraced the disease as part of her actor's arsenal and calls it "a gift".
"I have the gift of bipolar disorder and having the experience of high highs and low lows and being able to draw from those experiences and showing it on the screen. I show how mental illness affects everyone in the family."
Her book talks about her father's addiction to alcohol and how close she came to suicide before her disorder was controlled with drugs.
"Things that we used to see as diseases, with newer medications, are really like superpowers. I've experienced things that most people don't experience. Thank God that people don't have to experience the lows, but for people to get to feel it through my acting is a gift.
"I'm in the right profession to have it."
Bello is in a relationship with mindfulness teacher Elijah AllanBlitz and has a teenage son from an earlier marriage.
Lights Out deploys a neat visual trick - when the lights are switched off, a silhouette becomes visible; it disappears when the lights come back on.
Swedish director David F. Sandberg first used the premise in a 2013 short film that went viral on the Internet. It caught the attention of the major studios, leading to the full-length feature, which opens here tomorrow.
Co-produced by James Wan, director of The Conjuring (2013) and Furious 7 (2015), the film opened earlier this month in the US to strong box-office results. A sequel has been announced.
I have the gift of bipolar disorder and having the experience of high highs and low lows and being able to draw from those experiences and showing it on the screen.
ACTRESS MARIA BELLO
Bello is not particularly drawn to the horror genre, but she liked the script for its strong character- driven story. She also puts the film's commercial appeal down to the universal fear of the dark.
"People are afraid of the unknown and we are afraid of our own shadows. I like to say that with this movie, it's like you are walking in a forest and you hear a twig snap behind you.
"You look, see nothing and you don't worry. Then suddenly, it's snap, snap, snap, snap all around you and you start to run and you have no idea what's happening. This movie is like that, for an hour and a half."
• Lights Out opens in cinemas tomorrow.