TV repeats and familiar festive songs can help people with dementia by stimulating memories and keeping the brain active.
Christmas can be an unsettling time for those with dementia.
But experts say singing along to songs like White Christmas can stimulate "emotional memories".
And while people with dementia might not remember the exact details of It's A Wonderful Life, they may recall how they felt at the end of the film, reports BBC.
NHS England's national clinical director for dementia, Prof Alistair Burns, says Christmas can sometimes be strange or confusing for those living with dementia.
Lots of social engagements and a steady stream of house guests coming through the door have the potential to be unsettling.
But he says watching familiar films or singing along to favourite songs can help make the festive season easier to navigate.
"People with dementia might find it hard to follow convoluted conversations amid the chaos and noise of Christmas and can end up feeling excluded.
"Gathering the family round to watch a much-loved classic film, thumb through an old photo album, play a family game or even sing along to a favourite carol can bring people together and help everybody feel part of the fun."
Experts say it is the emotional details of a favourite film or song that remain lodged in our minds.
Rekindling them improves a feeling of connectedness with other people which is important for both people with dementia and their friends and families.
NHS England has this advice on how to make Christmas easier to cope with for someone with dementia.
Help people who are frail or living with dementia feel included by getting them to assist with hanging a bauble or other simple tasks
Don't overload on food - a full plate can be difficult to tackle for somebody with dementia who might have eating difficulties
Prof Burns is also urging people to look out for signs of dementia among older family members and friends over Christmas.
These might include emotional changes and forgetfulness which can sometimes be the first indication that someone has dementia.
Kathryn Smith, chief operating officer at the Alzheimer's Society, says Christmas can pose difficulties for the 850,000 people living with dementia in the UK, but there are strategies that can help.
"Whether it's an old song they used to enjoy or a classic Christmas film, reminiscing can be beneficial to someone with dementia - it can help to maintain their self-esteem, confidence and sense of self, as well as improve social interactions with others.
"However, every person with dementia is different, so it's important to listen and accommodate your loved one's unique needs and wishes."