Sia opens up about her six-year struggle with alcohol and drug addiction during Carpool Karaoke, sings 'Diamonds'

The reason Sia covers her face up in public is much darker than we'd initially thought.

The Aussie singer clarified more details about her face-covering wigs during James Corden's latest Carpool Karaoke session.

Watch the clip above from The Late Late Show to see Sia, 40, detail how her past struggles with drug and alcohol addiction led to her masked onstage persona.

Sia previously told Ellen DeGeneres that she hides her face to avoid paparazzi taking pictures of her going to the shops.

"Well it's just so that I can go to Target and buy a hose if I want to,' she said. "Or if I find I'm in need of a restroom, I can go in the side of the road, no one would be following me with a camera trying to get a shot."