Alfonso Cuaron's space thriller Gravity has been one of the must-see titles of the 2013 edition of the Toronto International Film Festival, with critics marvelling at Sandra Bullock's compelling performance as an astronaut catastrophically adrift in space and the film's impressive 3D visuals.

"It's about rebirth. There's a moment in someone's life when they don't think there's a reason to get up anymore in the morning. What is the reason to keep digging? Why do we keep trying every day?" Bullock told CBC News on the red carpet Sunday night ahead of the film's TIFF gala premiere. 

"I love that about [Gravity]. And being put in a situation where a human being, when my character, doesn't care about life anymore. What makes her want to live? I loved that."

Cuaron, who co-wrote the script with his son Jonas, spent years working on the eye-popping, special effects-heavy project.

"Working with this technology, it's so alien and inhuman. To find someone whose performance who can work with that and yet find the truth behind that ... the performance is generated through her eyes, yet she holds the film. You're completely enthralled," producer David Heyman said of Bullock Monday morning at the film's TIFF press conference.

The Toronto International Film Festival continues through Sept. 15.

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Sandra Bullock stars in Gravity as an astronaut who becomes adrift in space. (TIFF)