A nursing home worker who was captured on a hidden camera repeatedly slapping and hitting an elderly dementia patient has been sentenced to at least six months in detention, which she will serve either in prison or at home.

Dana Gray, 59, was working in The Poplars nursing home in the Sydney suburb of North Epping in 2017 when one of her colleagues became suspicious of her behaviour.

He set up a hidden camera in the room of an 85-year-old resident, who suffered from dementia, and who the Burwood Local Court heard was "defenceless and vulnerable".

The video, which was played in court, shows Gray slapping and pushing the elderly lady and pulling off her clothes aggressively before taking a bag filled with rubbish and hitting her again.

The 85-year-old lady, who cannot be named, can be heard screaming and sobbing in the video.

"This is domestic violence," Magistrate Robyn Denes told the court, adding the offence involved "gratuitous cruelty".

She said Gray was in a position of trust and the victim was completely defenceless.

"She cannot complain, doesn't have the ability to defend herself. She's entirely defenceless."

Gray was granted bail after her sentencing, while she is assessed for suitability for home detention.

She received a full custodial sentence of 17 months and will be eligible for parole after six months.

In sentencing, Magistrate Denes said while Gray pleaded guilty to the abuse, she showed little remorse for her actions and accused her of "victim-blaming".

"The degree of violence used in this instance is extreme," the magistrate said.

Anyone with a parent or loved on in aged care would be deeply concerned by Gray's behaviour, Magistrate Denes added.

"What happened to [the victim] is everyone's worst nightmare."

The matter will return to court in September.