I HAVE a confession to make. I can’t stand It’s a Wonderful Life.

I know it’s meant to be the best Christmas film ever, a sentimental classic for the sentimental season, but I find it cloyingly twee.

I’d still watch it if it came on the telly though. At this time of year, I’ll watch any old tosh. On Sunday afternoon, while putting my Christmas tree up, I was half-watching a film, one of Channel 5’s cheesiest, called A Very Yorkshire Christmas, which was so utterly awful I almost enjoyed it.

Christmas films are schmaltzy, saccharine, entirely predictable...and we can’t get enough of them. We wouldn’t expect any of them to be up for Oscars, but at least one of them is probably in our Top 10 favourite movies.

There are entire TV channels devoted to festive films, and this year Netflix is saturated with such gems as A Castle For Christmas, where Brooke Shields falls for a Scottish duke, which sounds delightfully bad.

What is it about this cheesy genre that we have such a huge appetite for every year? It’s all down to science, apparently.

“There’s a hormone called oxytocin, which is produced when we want to bond emotionally with each other,” says psychotherapist Noel McDermott (noelmcdermott.net).“During Christmas, when we’re meeting people that we love, oxytocin levels go through the roof.”

It’s not the only festive feelgood hormone; McDermott says we also get “reward hormones for being pro-social” with other humans.

So how does all this fit in with corny Christmas films? Says McDermott: “At this time of year, because we’re specifically focused on pro-social activities, these films make a lot more sense because they produce similar types of hormonal responses in us. So we feel ‘loved up’ when we’re watching them.”

It’s such a good fit it doesn’t matter that festive movies aren’t exactly cutting-edge cinema. As McDermott says, these films don’t tend to have great, nuanced characters or complex plots, but none of that matters because they make us feel “close to other people”.

We're drawn towards Christmas films each year because we’re creatures of habit, and it has become something of a ritual for many of us to re-watch old classics. Many families have their own Christmas movie traditions. My niece is 23 now but we still watch The Muppet Christmas Carol together with hot chocolate and biscuits because she’s loved it since she was little. Every Christmas Eve I used to watch the Alastair Sim Scrooge with my dad, and it remains my favourite festive film. And even though it’s not technically a Christmas film, I can’t get through the season without watching The Sound of Music because it reminds me of cosy childhood Christmases.

Whether it’s Home Alone or Die Hard, Miracle on 34th Street or Elf, Holiday Inn or Love Actually, we all have go-to festive movies we love to curl up with. Like Christmas itself, they’re a sickly brew of nostalgia, joy, romance and melancholy (and action stunts, if you’re one of those people who insist that Die Hard is a Christmas movie).

Comfort, predictability and structure are “essential for psychological security”, says McDermott: “The predictability of these films - we know exactly what’s going to happen - means we can relax, not be anxious, and just really enjoy it.”

And after another tense year of Covid-related anxiety, safe and predictable might be just what we need right now.